<?xml version="1.0" encoding="US-ASCII"?>
<!-- DFIN New ActiveDisclosure (SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date :2023-08-07T09:37:36.6608+00:00 -->
<!-- Copyright (c) 2023 Donnelly Financial Solutions, Inc. All Rights Reserved. -->
<xsd:schema targetNamespace="http://biodesix.com/20230630" attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2020-01-21" xmlns:enum2="http://xbrl.org/2020/extensible-enumerations-2.0" xmlns:srt="http://fasb.org/srt/2022" xmlns:stpr="http://xbrl.sec.gov/stpr/2022" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:us-gaap="http://fasb.org/us-gaap/2022" xmlns:dei="http://xbrl.sec.gov/dei/2022" xmlns:bdsx="http://biodesix.com/20230630" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xlink="http://www.w3.org/1999/xlink">
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/instance"/>
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/linkbase"/>
  <xsd:import schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" namespace="http://xbrl.org/2005/xbrldt"/>
  <xsd:import schemaLocation="https://xbrl.sec.gov/stpr/2022/stpr-2022.xsd" namespace="http://xbrl.sec.gov/stpr/2022"/>
  <xsd:import schemaLocation="https://www.xbrl.org/2020/extensible-enumerations-2.0.xsd" namespace="http://xbrl.org/2020/extensible-enumerations-2.0"/>
  <xsd:import schemaLocation="https://xbrl.sec.gov/dei/2022/dei-2022.xsd" namespace="http://xbrl.sec.gov/dei/2022"/>
  <xsd:import schemaLocation="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd" namespace="http://fasb.org/us-gaap/2022"/>
  <xsd:import schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd" namespace="http://www.xbrl.org/dtr/type/2020-01-21"/>
  <xsd:import schemaLocation="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd" namespace="http://fasb.org/srt/2022"/>
  <xsd:annotation>
    <xsd:appinfo>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bdsx-20230630_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:title="Labels link" xlink:type="simple"/>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bdsx-20230630_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:title="Presentation link" xlink:type="simple"/>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bdsx-20230630_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:title="Definition link" xlink:type="simple"/>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bdsx-20230630_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:title="Calculation link" xlink:type="simple"/>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DocumentDocumentAndEntityInformation" id="Role_DocumentDocumentAndEntityInformation">
        <link:definition>100000 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_StatementCondensedBalanceSheets" id="Role_StatementCondensedBalanceSheets">
        <link:definition>100010 - Statement - Condensed Balance Sheets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsForOperatingLeasesDetails2" id="DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsForOperatingLeasesDetails2">
        <link:definition>100020 - Disclosure - Leases - Summary of Future Minimum Lease Payments for Operating Leases (Details) 2</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_StatementCondensedBalanceSheetsParenthetical" id="Role_StatementCondensedBalanceSheetsParenthetical">
        <link:definition>100030 - Statement - Condensed Balance Sheets (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_StatementCondensedStatementsOfOperations" id="Role_StatementCondensedStatementsOfOperations">
        <link:definition>100040 - Statement - Condensed Statements of Operations</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/StatementCondensedStatementsOfStockholdersDeficitEquity" id="StatementCondensedStatementsOfStockholdersDeficitEquity">
        <link:definition>100050 - Statement - Condensed Statements of Stockholders' (Deficit) Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_StatementCondensedStatementsOfCashFlows" id="Role_StatementCondensedStatementsOfCashFlows">
        <link:definition>100060 - Statement - Condensed Statements of Cash Flows</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureOrganizationAndDescriptionOfBusiness" id="Role_DisclosureOrganizationAndDescriptionOfBusiness">
        <link:definition>100070 - Disclosure - Organization and Description of Business</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies" id="Role_DisclosureSummaryOfSignificantAccountingPolicies">
        <link:definition>100080 - Disclosure - Summary of Significant Accounting Policies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureRecentlyIssuedAccountingStandards" id="Role_DisclosureRecentlyIssuedAccountingStandards">
        <link:definition>100090 - Disclosure - Recently Issued Accounting Standards</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureFairValue" id="Role_DisclosureFairValue">
        <link:definition>100100 - Disclosure - Fair Value</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSupplementaryBalanceSheetInformation" id="Role_DisclosureSupplementaryBalanceSheetInformation">
        <link:definition>100110 - Disclosure - Supplementary Balance Sheet Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureDebt" id="Role_DisclosureDebt">
        <link:definition>100120 - Disclosure - Debt</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureLeases" id="DisclosureLeases">
        <link:definition>100130 - Disclosure - Leases</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureConvertiblePreferredStock" id="Role_DisclosureConvertiblePreferredStock">
        <link:definition>100140 - Disclosure - Convertible Preferred Stock</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureWarrantsToPurchaseConvertiblePreferredStock" id="Role_DisclosureWarrantsToPurchaseConvertiblePreferredStock">
        <link:definition>100150 - Disclosure - Warrants to Purchase Convertible Preferred Stock</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureEquity1" id="DisclosureEquity1">
        <link:definition>100160 - Disclosure - Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureRevenueAndAccountsReceivableCreditConcentration" id="Role_DisclosureRevenueAndAccountsReceivableCreditConcentration">
        <link:definition>100170 - Disclosure - Revenue and Accounts Receivable Credit Concentration</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureShareBasedCompensation" id="Role_DisclosureShareBasedCompensation">
        <link:definition>100180 - Disclosure - Share-Based Compensation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureNetLossPerCommonShare" id="DisclosureNetLossPerCommonShare">
        <link:definition>100190 - Disclosure - Net Loss per Common Share</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureIncomeTaxes" id="Role_DisclosureIncomeTaxes">
        <link:definition>100200 - Disclosure - Income Taxes</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureCommitmentsAndContingencies" id="Role_DisclosureCommitmentsAndContingencies">
        <link:definition>100210 - Disclosure - Commitments and Contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureSubsequentEvents" id="DisclosureSubsequentEvents">
        <link:definition>100220 - Disclosure - Subsequent Events</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies" id="Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies">
        <link:definition>100230 - Disclosure - Summary of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureFairValueTables" id="Role_DisclosureFairValueTables">
        <link:definition>100240 - Disclosure - Fair Value (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSupplementaryBalanceSheetInformationTables" id="Role_DisclosureSupplementaryBalanceSheetInformationTables">
        <link:definition>100250 - Disclosure - Supplementary Balance Sheet Information (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureDebtTables" id="Role_DisclosureDebtTables">
        <link:definition>100260 - Disclosure - Debt (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureLeasesTables" id="DisclosureLeasesTables">
        <link:definition>100270 - Disclosure - Leases (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureWarrantsToPurchaseConvertiblePreferredStockTables" id="Role_DisclosureWarrantsToPurchaseConvertiblePreferredStockTables">
        <link:definition>100280 - Disclosure - Warrants to Purchase Convertible Preferred Stock (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureRevenueAndAccountsReceivableCreditConcentrationTables" id="Role_DisclosureRevenueAndAccountsReceivableCreditConcentrationTables">
        <link:definition>100290 - Disclosure - Revenue and Accounts Receivable Credit Concentration (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureShareBasedCompensationTables" id="Role_DisclosureShareBasedCompensationTables">
        <link:definition>100300 - Disclosure - Share-Based Compensation (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureNetLossPerCommonShareTables" id="DisclosureNetLossPerCommonShareTables">
        <link:definition>100310 - Disclosure - Net Loss per Common Share (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureOrganizationAndDescriptionOfBusinessAdditionalInformationDetails" id="Role_DisclosureOrganizationAndDescriptionOfBusinessAdditionalInformationDetails">
        <link:definition>100320 - Disclosure - Organization and Description of Business - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails" id="Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails">
        <link:definition>100330 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureFairValueSummaryOfFairValueOfOutstandingBorrowingsDetails" id="Role_DisclosureFairValueSummaryOfFairValueOfOutstandingBorrowingsDetails">
        <link:definition>100340 - Disclosure - Fair Value - Summary of Fair Value of Outstanding Borrowings (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureFairValueScheduleOfReportedFairValuesOfContingentConsiderationAndWarrantLiabilitiesDetails" id="DisclosureFairValueScheduleOfReportedFairValuesOfContingentConsiderationAndWarrantLiabilitiesDetails">
        <link:definition>100350 - Disclosure - Fair Value - Schedule of Reported Fair values of Contingent Consideration and Warrant Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureFairValueScheduleOfChangesInContingentConsiderationAndWarrantLiabilitiesDetails" id="DisclosureFairValueScheduleOfChangesInContingentConsiderationAndWarrantLiabilitiesDetails">
        <link:definition>100360 - Disclosure - Fair Value - Schedule of Changes in Contingent Consideration and Warrant Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureFairValueAdditionalInformationDetails" id="Role_DisclosureFairValueAdditionalInformationDetails">
        <link:definition>100370 - Disclosure - Fair Value - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSupplementaryBalanceSheetInformationPropertyAndEquipmentDetails" id="Role_DisclosureSupplementaryBalanceSheetInformationPropertyAndEquipmentDetails">
        <link:definition>100380 - Disclosure - Supplementary Balance Sheet Information - Property and Equipment (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSupplementaryBalanceSheetInformationAdditionalInformationDetails" id="Role_DisclosureSupplementaryBalanceSheetInformationAdditionalInformationDetails">
        <link:definition>100390 - Disclosure - Supplementary Balance Sheet Information - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSupplementaryBalanceSheetInformationIntangibleAssetsExcludingGoodwillDetails" id="Role_DisclosureSupplementaryBalanceSheetInformationIntangibleAssetsExcludingGoodwillDetails">
        <link:definition>100400 - Disclosure - Supplementary Balance Sheet Information - Intangible Assets, Excluding Goodwill (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureSupplementaryBalanceSheetInformationScheduleOfAmortizationRelatedToRemainingNetIntangibleAssetsScheduleToAmortizeDetails" id="DisclosureSupplementaryBalanceSheetInformationScheduleOfAmortizationRelatedToRemainingNetIntangibleAssetsScheduleToAmortizeDetails">
        <link:definition>100410 - Disclosure - Supplementary Balance Sheet Information - Schedule of Amortization Related to Remaining Net Intangible Assets Schedule to Amortize (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureSupplementaryBalanceSheetInformationAccruedLiabilitiesDetails" id="Role_DisclosureSupplementaryBalanceSheetInformationAccruedLiabilitiesDetails">
        <link:definition>100420 - Disclosure - Supplementary Balance Sheet Information - Accrued Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureDebtSummaryOfLongTermNotesPayableDetails" id="Role_DisclosureDebtSummaryOfLongTermNotesPayableDetails">
        <link:definition>100430 - Disclosure - Debt - Summary of Long-term Notes Payable (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureDebtAdditionalInformationDetails" id="Role_DisclosureDebtAdditionalInformationDetails">
        <link:definition>100440 - Disclosure - Debt - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureDebtScheduledPrincipalRepaymentsMaturitiesOfLongTermObligationsDetails" id="Role_DisclosureDebtScheduledPrincipalRepaymentsMaturitiesOfLongTermObligationsDetails">
        <link:definition>100450 - Disclosure - Debt - Scheduled Principal Repayments (Maturities) of Long-term Obligations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureLeasesAdditionalInformationDetails" id="DisclosureLeasesAdditionalInformationDetails">
        <link:definition>100460 - Disclosure - Leases - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsForOperatingLeasesDetails" id="DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsForOperatingLeasesDetails">
        <link:definition>100470 - Disclosure - Leases - Summary of Future Minimum Lease Payments for Operating Leases (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsForOperatingLeasesParentheticalDetails" id="DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsForOperatingLeasesParentheticalDetails">
        <link:definition>100480 - Disclosure - Leases - Summary of Future Minimum Lease Payments for Operating Leases (Parenthetical) (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureConvertiblePreferredStockAdditionalInformationDetails" id="Role_DisclosureConvertiblePreferredStockAdditionalInformationDetails">
        <link:definition>100490 - Disclosure - Convertible Preferred Stock - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureWarrantsToPurchaseConvertiblePreferredStockSummaryOfActivityForConvertiblePreferredStockWarrantsOutstandingDetails" id="Role_DisclosureWarrantsToPurchaseConvertiblePreferredStockSummaryOfActivityForConvertiblePreferredStockWarrantsOutstandingDetails">
        <link:definition>100500 - Disclosure - Warrants to Purchase Convertible Preferred Stock - Summary of Activity for Convertible Preferred Stock Warrants Outstanding (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureWarrantsToPurchaseConvertiblePreferredStockSummaryOfActivityForConvertiblePreferredStockWarrantsOutstandingParentheticalDetails" id="Role_DisclosureWarrantsToPurchaseConvertiblePreferredStockSummaryOfActivityForConvertiblePreferredStockWarrantsOutstandingParentheticalDetails">
        <link:definition>100510 - Disclosure - Warrants to Purchase Convertible Preferred Stock - Summary of Activity for Convertible Preferred Stock Warrants Outstanding (Parenthetical) (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureEquityAdditionalInformationDetails" id="DisclosureEquityAdditionalInformationDetails">
        <link:definition>100520 - Disclosure - Equity - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureRevenueAndAccountsReceivableCreditConcentrationAdditionalInformationDetails" id="Role_DisclosureRevenueAndAccountsReceivableCreditConcentrationAdditionalInformationDetails">
        <link:definition>100530 - Disclosure - Revenue and Accounts Receivable Credit Concentration - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureRevenueAndAccountsReceivableCreditConcentrationSummaryOfRevenueDetails" id="Role_DisclosureRevenueAndAccountsReceivableCreditConcentrationSummaryOfRevenueDetails">
        <link:definition>100540 - Disclosure - Revenue and Accounts Receivable Credit Concentration - Summary of Revenue (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureRevenueAndAccountsReceivableCreditConcentrationSummaryOfRevenueAndAccountsReceivableByThirdPartyPayorsAndOtherCustomersDetails" id="Role_DisclosureRevenueAndAccountsReceivableCreditConcentrationSummaryOfRevenueAndAccountsReceivableByThirdPartyPayorsAndOtherCustomersDetails">
        <link:definition>100550 - Disclosure - Revenue and Accounts Receivable Credit Concentration - Summary of Revenue and Accounts Receivable by Third-party Payors and Other Customers (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureShareBasedCompensationAdditionalInformationDetails" id="Role_DisclosureShareBasedCompensationAdditionalInformationDetails">
        <link:definition>100560 - Disclosure - Share-Based Compensation - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureSharebasedCompensationSummaryOfSharebasedCompensationExpenseDetails" id="DisclosureSharebasedCompensationSummaryOfSharebasedCompensationExpenseDetails">
        <link:definition>100570 - Disclosure - Share-Based Compensation - Summary of Share-based Compensation Expense (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureShareBasedCompensationSummaryOfStockOptionActivityDetails" id="Role_DisclosureShareBasedCompensationSummaryOfStockOptionActivityDetails">
        <link:definition>100580 - Disclosure - Share-Based Compensation - Summary of Stock Option Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureSharebasedCompensationSummaryOfRestrictedStockUnitsActivityDetails" id="DisclosureSharebasedCompensationSummaryOfRestrictedStockUnitsActivityDetails">
        <link:definition>100590 - Disclosure - Share-Based Compensation - Summary of Restricted Stock Units Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfComputationOfBasicAndDilutedLossPerShareAttributableToStockholdersDetails" id="DisclosureNetLossPerCommonShareScheduleOfComputationOfBasicAndDilutedLossPerShareAttributableToStockholdersDetails">
        <link:definition>100600 - Disclosure - Net Loss per Common Share - Schedule of Computation of Basic and Diluted Loss per Share Attributable to Stockholders (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfCommonStockEquivalentsExcludedFromDilutedNetLossAttributableToCommonStockholdersDetails" id="DisclosureNetLossPerCommonShareScheduleOfCommonStockEquivalentsExcludedFromDilutedNetLossAttributableToCommonStockholdersDetails">
        <link:definition>100610 - Disclosure - Net Loss per Common Share - Schedule of Common Stock Equivalents Excluded from Diluted Net Loss Attributable to Common Stockholders (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureIncomeTaxesAdditionalInformationDetails" id="Role_DisclosureIncomeTaxesAdditionalInformationDetails">
        <link:definition>100620 - Disclosure - Income Taxes - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails" id="Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails">
        <link:definition>100630 - Disclosure - Commitments and Contingencies - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://biodesix.com/20230630/taxonomy/role/DisclosureSubsequentEventsAdditionalInformationDetails" id="DisclosureSubsequentEventsAdditionalInformationDetails">
        <link:definition>100640 - Disclosure - Subsequent Events - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element id="bdsx_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionsExercisesInPeriodWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionsExercisesInPeriodWeightedAverageExercisePrice" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_BusinessCombinationContingentConsiderationShares" name="BusinessCombinationContingentConsiderationShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_LitigationClaimsAndAssessmentsMember" name="LitigationClaimsAndAssessmentsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SubscriptionAgreementsDescription" name="SubscriptionAgreementsDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_DebtIssuanceCostsIncludedInAccountsPayableAndOtherAccruedLiabilities" name="DebtIssuanceCostsIncludedInAccountsPayableAndOtherAccruedLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_SubscriptionAgreementsMember" name="SubscriptionAgreementsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_IntangibleAssetsAccumulatedAmortizationExcludingGoodwill" name="IntangibleAssetsAccumulatedAmortizationExcludingGoodwill" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_IntegratedDiagnosticsIncMember" name="IntegratedDiagnosticsIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_AdditionalWarrantsAmount" name="AdditionalWarrantsAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_CentennialValleyPropertiesILlcLeaseAgreementMember" name="CentennialValleyPropertiesILlcLeaseAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_DeferredOfferingCostsIncludedInAccruedLiabilities" name="DeferredOfferingCostsIncludedInAccruedLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_TwoThousandAndTwentyOneTermLoanPartialRepaymentInApril2022Member" name="TwoThousandAndTwentyOneTermLoanPartialRepaymentInApril2022Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionsGrantsInPeriodWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionsGrantsInPeriodWeightedAverageExercisePrice" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PercentageOfInterestOnContingentConsideration" name="PercentageOfInterestOnContingentConsideration" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PerceptiveTermLoanMember" name="PerceptiveTermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SecondAmendmentMember" name="SecondAmendmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_MinimumCashBalanceAtMaturityDate" name="MinimumCashBalanceAtMaturityDate" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_LeasedPropertyBuildingCapacity" name="LeasedPropertyBuildingCapacity" type="dtr-types:areaItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PPPLoanMember" name="PPPLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_AccruedClinicalTrialExpenseCurrent" name="AccruedClinicalTrialExpenseCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_WeightedAverageLeaseTermDiscountRateFinanceOperatingTableTextBlock" name="WeightedAverageLeaseTermDiscountRateFinanceOperatingTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_LPCFacilityMember" name="LPCFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PurchasedTechnologyMember" name="PurchasedTechnologyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_AdditionalTenantImprovementAllowanceAmount" name="AdditionalTenantImprovementAllowanceAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_FairValueMeasurementWithUnobservableInputsInterestExpense" name="FairValueMeasurementWithUnobservableInputsInterestExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_BusinessCombinationContingentConsiderationFinalPayment" name="BusinessCombinationContingentConsiderationFinalPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_SecuritiesPurchaseAgreementsMember" name="SecuritiesPurchaseAgreementsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SharesCommittedUnderESPPMember" name="SharesCommittedUnderESPPMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_NumberOfCommercialBloodBasedTest" name="NumberOfCommercialBloodBasedTest" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PromissoryNoteTwoMember" name="PromissoryNoteTwoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_TwoThousandTwentyOneTermLoanPrincipalRepaymentMember" name="TwoThousandTwentyOneTermLoanPrincipalRepaymentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_AreaOfLeasedPremisedObligatedToPayBaseRent" name="AreaOfLeasedPremisedObligatedToPayBaseRent" type="dtr-types:areaItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_WarrantsForConvertiblePreferredStockTextBlock" name="WarrantsForConvertiblePreferredStockTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_ProceedsFromIssuanceOfTermLoanAndNotesPayable" name="ProceedsFromIssuanceOfTermLoanAndNotesPayable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_LesseeOperatingAndFinanceLeasesTextBlock" name="LesseeOperatingAndFinanceLeasesTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_AccruedInterestAmortizationOfDebtIssuanceCostsAndOther" name="AccruedInterestAmortizationOfDebtIssuanceCostsAndOther" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_RevenueShareExpenses" name="RevenueShareExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_NSCLCPOCTrialMember" name="NSCLCPOCTrialMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_DiligenceExpenseAndLegalFees" name="DiligenceExpenseAndLegalFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_PerceptiveTermLoanFacilityMember" name="PerceptiveTermLoanFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_WarrantLiabilityMember" name="WarrantLiabilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_TermLoanPartialRepaymentMember" name="TermLoanPartialRepaymentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_RepurchaseMember" name="RepurchaseMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SummaryOfSignificantAccountingPoliciesTable" name="SummaryOfSignificantAccountingPoliciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SaleOfStockStockIssuablePerDayValue" name="SaleOfStockStockIssuablePerDayValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_InterestExpenseDueToPassageOfTimeAndFixedPaymentSchedule" name="InterestExpenseDueToPassageOfTimeAndFixedPaymentSchedule" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_TheStateOfColoradoMember" name="TheStateOfColoradoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsvestedInPeriodAmount" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsvestedInPeriodAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_MaximumPercentageOfCommonStockAllowedToPurchaseByCounterparty" name="MaximumPercentageOfCommonStockAllowedToPurchaseByCounterparty" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_TwoThousandTwentyOneTermLoanAndPromissoryNoteOneMember" name="TwoThousandTwentyOneTermLoanAndPromissoryNoteOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_AVEOOncologyMember" name="AVEOOncologyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_FairValueLiabilitiesMeasuredOnRecurringBasisTable" name="FairValueLiabilitiesMeasuredOnRecurringBasisTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_LesseeOperatingLeaseLiabilityAmountRepresentingTenantImprovementAllowances" name="LesseeOperatingLeaseLiabilityAmountRepresentingTenantImprovementAllowances" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_ProceedsFromIssuanceOfCommonStockNet" name="ProceedsFromIssuanceOfCommonStockNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_FairValueLiabilitiesMeasuredOnRecurringBasisLineItems" name="FairValueLiabilitiesMeasuredOnRecurringBasisLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PurchaseAgreementTerm" name="PurchaseAgreementTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_LicenseAgreementExpiryDate" name="LicenseAgreementExpiryDate" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_AdjustmentsToAdditionalPaidInCapitalDeferredOfferingCosts" name="AdjustmentsToAdditionalPaidInCapitalDeferredOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_LeaseCommencementDate" name="LeaseCommencementDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_CARESActMember" name="CARESActMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_NumberOfSARSCoV2Test" name="NumberOfSARSCoV2Test" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PercentageOfDevelopmentAndRegulatoryCostsExercisedUsingOptOutRight" name="PercentageOfDevelopmentAndRegulatoryCostsExercisedUsingOptOutRight" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PaymentsForProceedsFromPatentCostsAndIntangibleAssetAcquisitionNet" name="PaymentsForProceedsFromPatentCostsAndIntangibleAssetAcquisitionNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_MinimumAnnualVolumePercentageThereafter" name="MinimumAnnualVolumePercentageThereafter" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFiveAndThereafter" name="LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFiveAndThereafter" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_InitialWarrantsAmount" name="InitialWarrantsAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_NotesPayable2018NotesMember" name="NotesPayable2018NotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PercentageOfProbabilitiesOfContingentConsiderationSuccessfulAchievementMilestoneDiscountRatesRange" name="PercentageOfProbabilitiesOfContingentConsiderationSuccessfulAchievementMilestoneDiscountRatesRange" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_EquityFinancingProgramsMember" name="EquityFinancingProgramsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SeriesA3PreferredStockMember" name="SeriesA3PreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PercentageOfLicenseIncomeGeneratedFromLicensing" name="PercentageOfLicenseIncomeGeneratedFromLicensing" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_SharesIssuedAsCommitmentFeeValue" name="SharesIssuedAsCommitmentFeeValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_TenantImprovementsIncurredDuringThePeriod" name="TenantImprovementsIncurredDuringThePeriod" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_CellCartaLicenseMember" name="CellCartaLicenseMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_LeaseExpirationMonthYear" name="LeaseExpirationMonthYear" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_AtTheMoneyFacilityMember" name="AtTheMoneyFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_ThirdAmendmentToOur2021TermLoanMember" name="ThirdAmendmentToOur2021TermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SupplementalCashFlowInformationLeasesFinanceTableTextBlock" name="SupplementalCashFlowInformationLeasesFinanceTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_ScheduleOfFutureMinimumRentalPaymentsForOperatingAndFinanceLeases" name="ScheduleOfFutureMinimumRentalPaymentsForOperatingAndFinanceLeases" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PercentageOfDevelopmentAndRegulatoryCosts" name="PercentageOfDevelopmentAndRegulatoryCosts" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_ExitFeePayment" name="ExitFeePayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_BusinessAcquisitionContingentConsiderationGrossMarginTargetPeriod" name="BusinessAcquisitionContingentConsiderationGrossMarginTargetPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_FiniteLivedIntangibleAssetsAmortizationExpenseYearFiveAndThereafter" name="FiniteLivedIntangibleAssetsAmortizationExpenseYearFiveAndThereafter" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_LincolnParkMember" name="LincolnParkMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_FourthAmendmentTo2021TermLoanMember" name="FourthAmendmentTo2021TermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_LandlordContributionTowardsCostOfConstructionAndTenantImprovements" name="LandlordContributionTowardsCostOfConstructionAndTenantImprovements" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_LossMember" name="LossMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PercentageOfRevenueSharePaymentRelatedToAcquiredDiagnosticTestRecognizedRevenueForNonScreeningTests" name="PercentageOfRevenueSharePaymentRelatedToAcquiredDiagnosticTestRecognizedRevenueForNonScreeningTests" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_NumberOfFacility" name="NumberOfFacility" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_InterestRateOnExtraAllowanceAmount" name="InterestRateOnExtraAllowanceAmount" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_TwoThousandTwentyOneTermLoanAmendmentMember" name="TwoThousandTwentyOneTermLoanAmendmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_TermOfRoyaltyPaymentsFromFirstCommercialSale" name="TermOfRoyaltyPaymentsFromFirstCommercialSale" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_SaleOfStockStockIssuablePerDayShares" name="SaleOfStockStockIssuablePerDayShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_DiagnosticTestsMember" name="DiagnosticTestsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_EquityFinancingCostsIncludedInAccountsPayableAndOtherAccruedLiabilities" name="EquityFinancingCostsIncludedInAccountsPayableAndOtherAccruedLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_BusinessCombinationContingentConsiderationArrangementsCommonSharesRedemptionAmount" name="BusinessCombinationContingentConsiderationArrangementsCommonSharesRedemptionAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_FirstAmendmentMember" name="FirstAmendmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SummaryOfSignificantAccountingPoliciesLineItems" name="SummaryOfSignificantAccountingPoliciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_OtherMember" name="OtherMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_DescriptionOfOfferingPeriodUnderPlan" name="DescriptionOfOfferingPeriodUnderPlan" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_BioRadLicenseMember" name="BioRadLicenseMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour" name="LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_LeaseAgreementNumberOfOptionsToExtend" name="LeaseAgreementNumberOfOptionsToExtend" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_FourthMilestonePaymentAndInterest" name="FourthMilestonePaymentAndInterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_CommonStockIssuedForDeferredOfferingCosts" name="CommonStockIssuedForDeferredOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_ReductionInContingentConsideration" name="ReductionInContingentConsideration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_CommitmentSharesIssuableOnConditionalBasis" name="CommitmentSharesIssuableOnConditionalBasis" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_MilestonePayment" name="MilestonePayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_SeriesGConvertiblePreferredStockWarrantsMember" name="SeriesGConvertiblePreferredStockWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_LessorReimbursementsReceived" name="LessorReimbursementsReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_WeightedAveragePricePerShare" name="WeightedAveragePricePerShare" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_ClassOfWarrantOrRightAdditionalWarrantsOrRightsExercisable" name="ClassOfWarrantOrRightAdditionalWarrantsOrRightsExercisable" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_TenantImprovementAllowancesExpectedToBeReceived" name="TenantImprovementAllowancesExpectedToBeReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsOutstandingWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsOutstandingWeightedAverageExercisePrice" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_TenantImprovementAllowancesReceived" name="TenantImprovementAllowancesReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_FiclatuzumabMember" name="FiclatuzumabMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_CurrentPortionOfContingentConsiderationMember" name="CurrentPortionOfContingentConsiderationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_EstimatedPaymentToThirdParties" name="EstimatedPaymentToThirdParties" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_PrincipalRepaymentMember" name="PrincipalRepaymentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_RemainingEstimatedObligation" name="RemainingEstimatedObligation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_OncimmuneLimitedMember" name="OncimmuneLimitedMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_TwoThousandTwentyEquityIncentivePlanMember" name="TwoThousandTwentyEquityIncentivePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_ProceedsFromIssuanceOfCommonStockUnderEmployeeStockPurchasePlan" name="ProceedsFromIssuanceOfCommonStockUnderEmployeeStockPurchasePlan" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_PercentageOfFeePaymentsOnNetSales" name="PercentageOfFeePaymentsOnNetSales" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PrimarySourcesOfRevenueDescription" name="PrimarySourcesOfRevenueDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PromissoryNoteOneMember" name="PromissoryNoteOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_IssuanceOfPerceptiveWarrants" name="IssuanceOfPerceptiveWarrants" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_YearOfEndingRoyaltyPaymentsFromFirstCommercialSale" name="YearOfEndingRoyaltyPaymentsFromFirstCommercialSale" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_OriginalIssuanceDiscount" name="OriginalIssuanceDiscount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_RentAfterFixedEscalationProvisions" name="RentAfterFixedEscalationProvisions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_CashCollateralizedLetterOfCreditMember" name="CashCollateralizedLetterOfCreditMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PrepaymentPremiumPercentageOfAggregateOutstandingPrincipalAmount" name="PrepaymentPremiumPercentageOfAggregateOutstandingPrincipalAmount" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_TwoThousandTwentyOneTermLoanMember" name="TwoThousandTwentyOneTermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_FourthMilestoneAndInterestPaymentMade" name="FourthMilestoneAndInterestPaymentMade" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_StockIssuedDuringPeriodSharesForDeferredOfferingCosts" name="StockIssuedDuringPeriodSharesForDeferredOfferingCosts" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_SaleOfStockSharesIssuedAsCommitmentFee" name="SaleOfStockSharesIssuedAsCommitmentFee" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_SeriesA2PreferredStockMember" name="SeriesA2PreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_AtTheMarketFacilityMember" name="AtTheMarketFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_StockIssuableDuringPeriodValueCommittedShares" name="StockIssuableDuringPeriodValueCommittedShares" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_PublicOfferingPricePerShareOfCommonStock" name="PublicOfferingPricePerShareOfCommonStock" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_AstrazenecaUkMember" name="AstrazenecaUkMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_DeferredOfferingCostsAmortizedAgainstAdditionalPaidInCapital" name="DeferredOfferingCostsAmortizedAgainstAdditionalPaidInCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_OtherAssetsPolicyTextBlock" name="OtherAssetsPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_NumberOfPreferredStockConvertedIntoCommonStock" name="NumberOfPreferredStockConvertedIntoCommonStock" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PurchasesOfPropertyAndEquipmentIncludedInAccruedLiabilities" name="PurchasesOfPropertyAndEquipmentIncludedInAccruedLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_StockIssuedDuringPeriodValuesForDeferredOfferingCosts" name="StockIssuedDuringPeriodValuesForDeferredOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_PaymentOfEquityFinancingCosts" name="PaymentOfEquityFinancingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_PaymentOfDeferredOfferingCosts" name="PaymentOfDeferredOfferingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_OperatingLeaseRightOfUseAssetsObtainedInExchangeForLeaseLiabilitiesAtAdoptionOfAsc842" name="OperatingLeaseRightOfUseAssetsObtainedInExchangeForLeaseLiabilitiesAtAdoptionOfAsc842" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_SeriesA1PreferredStockMember" name="SeriesA1PreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_RemainingCapacityUnderTenantImprovementAllowancesPriorToReimbursementsExpectedToBeReceived" name="RemainingCapacityUnderTenantImprovementAllowancesPriorToReimbursementsExpectedToBeReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedAggregateIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedAggregateIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_OptionsAndRestrictedStockUnitsRSUsMember" name="OptionsAndRestrictedStockUnitsRSUsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PercentageOfRoyaltyPaymentsOnNetRevenue" name="PercentageOfRoyaltyPaymentsOnNetRevenue" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_UnitedHealthcareMember" name="UnitedHealthcareMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_CashCollateralizedMember" name="CashCollateralizedMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SeriesB1ConvertiblePreferredStockMember" name="SeriesB1ConvertiblePreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_ThirdAmendmentToApaAgreementMember" name="ThirdAmendmentToApaAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_MedicareMember" name="MedicareMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_BaseRentPerMonthFromCommencementDate" name="BaseRentPerMonthFromCommencementDate" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_ThirdAmendmentMember" name="ThirdAmendmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_NumberOfCancerTest" name="NumberOfCancerTest" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_PercentageOfRoyaltyPaymentsNotRequiredToPayOnNetRevenue" name="PercentageOfRoyaltyPaymentsNotRequiredToPayOnNetRevenue" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_BusinessAcquisitionContingentConsiderationNumberOfInstallments" name="BusinessAcquisitionContingentConsiderationNumberOfInstallments" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_IntegratedDiagnosticsAssetPurchaseAgreementMember" name="IntegratedDiagnosticsAssetPurchaseAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_AtTheMarketOfferingMember" name="AtTheMarketOfferingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_IndefiniteLivedIntangibleAssetsExcludingGoodwillGross" name="IndefiniteLivedIntangibleAssetsExcludingGoodwillGross" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_WarrantLiabilitiesFairValueDisclosure" name="WarrantLiabilitiesFairValueDisclosure" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_PromissoryNotesMember" name="PromissoryNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_OptionsToPurchaseCommonStockMember" name="OptionsToPurchaseCommonStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PeriodOfEscalationsOfSales" name="PeriodOfEscalationsOfSales" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_SeriesEConvertiblePreferredStockWarrantsMember" name="SeriesEConvertiblePreferredStockWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_AccretionOfLeaseLiability" name="AccretionOfLeaseLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bdsx_DirectCostsAndExpensesMember" name="DirectCostsAndExpensesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_ToBePaidOnSeptember302022Member" name="ToBePaidOnSeptember302022Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_RevenueShareAgreementMember" name="RevenueShareAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_DirectCostsAndExpenses" name="DirectCostsAndExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bdsx_CommonStockPurchaseAgreementMember" name="CommonStockPurchaseAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_PercentageOfRoyaltyPaymentsOnNetSales" name="PercentageOfRoyaltyPaymentsOnNetSales" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_BonusToOptionsProgramMember" name="BonusToOptionsProgramMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_SharesIssuedOrIssuableThresholdLimitDescription" name="SharesIssuedOrIssuableThresholdLimitDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_AreaOfOfficeSpaceLeased" name="AreaOfOfficeSpaceLeased" type="dtr-types:areaItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="bdsx_ContingentConsiderationMember" name="ContingentConsiderationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_OrganizationAndDescriptionOfBusinessAbstract" name="OrganizationAndDescriptionOfBusinessAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_ExistingShareholdersMember" name="ExistingShareholdersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bdsx_FairValueMeasurementWithUnobservableInputsPaymentsOfContingentConsideration" name="FairValueMeasurementWithUnobservableInputsPaymentsOfContingentConsideration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
</xsd:schema>
