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Module COAG-08 · Version 1.0

Mixing Studies Step by Step

A stepwise walk through the screening 1:1 patient-to-normal-pooled-plasma mixing study: when it is indicated, how to prepare and time it, how to read immediate versus incubated aPTT results, how to calculate a local index, and how to route the classified pattern to the right follow-up test.

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Who this module is for

Clinical laboratory scientists and coagulation bench staff performing or interpreting screening mixing studies, who have completed the introductory PT/aPTT and coagulation cascade modules.

Learning objectives

  • Explain the logic of a 1:1 patient plasma to normal pooled plasma mixing study as a test of whether a prolonged result behaves like factor replacement or persistent inhibition
  • Compare immediate and incubated mixing results and recognize a time-dependent inhibitory pattern
  • Apply a locally defined correction calculation and classify factor deficiency, inhibitor, and indeterminate patterns, then choose bounded follow-up testing

How completion works

Mark every required section done and answer every knowledge check in those sections correctly. The final save completes the module automatically.

Sources

10 sources

  1. 1. Centers for Medicare & Medicaid Services. 42 CFR Section 493.1269, Standard: Hematology. Federal regulation, United States. https://www.law.cornell.edu/cfr/text/42/493.1269

    Source note · federal regulation

  2. 2. College of American Pathologists. Hematology, Coagulation, and Clinical Microscopy Checklist, HEM.37937 Mixing Studies Procedure (Phase II). CAP Accreditation Program, 12.09.2025 edition.

    Source note · accreditation standard

  3. 3. Clinical and Laboratory Standards Institute. H47, One-Stage Prothrombin Time (PT) Test and Activated Partial Thromboplastin Time (APTT) Test, 3rd ed., March 7, 2023. Consensus standard. https://clsi.org/shop/standards/h47/

    Source note · consensus standard

  4. 4. Clinical and Laboratory Standards Institute. H60, Laboratory Testing for the Lupus Anticoagulant, 1st ed., 2014, reaffirmed September 2019. Consensus standard. https://clsi.org/shop/standards/h60/

    Source note · consensus standard

  5. 5. Adcock DM, Moore GW, Kershaw GW, Montalvao SAL, Gosselin RC. International Council for Standardization in Haematology recommendations for the performance and interpretation of activated partial thromboplastin time and prothrombin time mixing tests. Int J Lab Hematol. 2024;46:777-788. doi:10.1111/ijlh.14344. https://pubmed.ncbi.nlm.nih.gov/39009028/

    Source note · consensus standard

  6. 6. Gosselin RC, Moore GW, Kershaw GW, Montalvao S, Adcock DM. International Council for Standardization in Haematology Field Study Evaluating Optimal Interpretation Methods for Activated Partial Thromboplastin Time and Prothrombin Time Mixing Studies. Arch Pathol Lab Med. 2024;148:880-889. doi:10.5858/arpa.2023-0030-OA. https://pubmed.ncbi.nlm.nih.gov/38031817/

    Source note · peer-reviewed literature

  7. 7. Devreese KMJ, de Groot PG, de Laat B, et al. Guidance from the ISTH SSC for lupus anticoagulant/antiphospholipid antibodies: update of guidelines for LA detection and interpretation. J Thromb Haemost. 2020;18:2828-2839. doi:10.1111/jth.15047. https://www.islh.org/web/downloads/2020-LAC-guidance-JTH-16859413.pdf

    Source note · professional society guidance

  8. 8. Tiede A, Collins P, Knoebl P, et al. International recommendations on the diagnosis and treatment of acquired hemophilia A. Haematologica. 2020;105:1791-1801. doi:10.3324/haematol.2019.230771. https://pmc.ncbi.nlm.nih.gov/articles/PMC7327664/

    Source note · professional society guidance

  9. 9. Moser KA, Smock KJ. Direct oral anticoagulant interference in hemostasis assays. Hematology Am Soc Hematol Educ Program. 2021;2021:129-133. doi:10.1182/hematology.2021000241. https://pmc.ncbi.nlm.nih.gov/articles/PMC8791165/

    Source note · peer-reviewed literature

  10. 10. Molinari AC, Martini T, Banov L, Ierardi A, Leotta M, Strangio A, Santoro RC. Lupus anticoagulant detection under the magnifying glass. J Clin Med. 2023;12:6654. doi:10.3390/jcm12206654. https://pmc.ncbi.nlm.nih.gov/articles/PMC10607820/

    Source note · peer-reviewed literature