Daniel E. Sabath, MD, PhD

Professor | Head, Hematology Division, Department of Laboratory Medicine and Pathology | Chief of Service, Harborview Clinical Laboratories | Laboratory Director, Hematology and Coagulation Laboratories, UW Medical Center - Montlake and HMC

Maryam Asif, MD, MBBS

Assistant Professor | Associate Medical Director, Hematology and Coagulation Laboratories | Associate Medical Director, Transfusion Services

Rida A. Hasan, MD

Assistant Professor | Associate Medical Director, Transfusion Service Laboratories UW Medical Center - Montlake and Harborview Medical Center

Bernard Khor, MD, PhD

Affiliate Assistant Professor

Fabienne Lucas, MD, PhD

Assistant Professor | Associate Director of Hematology/Coagulation

Hamilton C. Tsang, MD

Associate Professor

The Clinical Coagulation Division is involved in clinical testing, research and teaching related to bleeding and thrombotic disorders.

Diagnostic Testing

A comprehensive set of clinical tests are available for the diagnosis and monitoring of bleeding and thrombotic disorders.

Testing for Hypercoagulable States

  • Inherited coagulation disorders including Antithrombin deficiency, Protein C deficiency, Protein S deficiency, elevated Factor VIII (with C-reactive protein to exclude acute phase response) and Activated Protein C Resistance. Tests may be ordered individually or as a panel with an interpretive report.
  • Lupus inhibitor testing (meeting current International Society of Hemostasis and Thrombosis standards) including the dilute Russell viper venom test, hexagonal phase phospholipid test, and testing for antibodies against cardiolipin and B2‑glycoprotein I (performed in UW Immunology laboratory). Tests may be ordered individually or as a panel with an interpretive report.
  • D‑dimer testing to assess the presence of acute thrombosis or resolution of thrombosis after therapy.
  • DNA testing for Factor V Leiden and Prothrombin mutations is offered by the UW Genetics laboratory.

Testing for Bleeding Disorders

  • Assays for specific clotting factors (II, V, VII, VIII, IX, X, XI, XII).
  • Testing for specific coagulation factor inhibitors, including inhibitors of Factors VIII, IX, and V.
  • Von Willebrand Disease testing including Factor VIII activity, von Willebrand Factor antigen and activity assays, and von Willebrand Factor multimer analysis, including interpretive report.
  • Platelet function studies including the PFA‑100 assay with ADP/collagen and epinephrine/collagen and platelet aggregometry studies measuring aggregation with impedance and granule release (ATP/luciferin assay). Interpretive reports are issued for aggregometry studies.

Anticoagulant Drug Testing

  • Anti‑Xa assays to monitor therapy with unfractionated heparin, low molecular weight heparins such as enoxaparin (Lovenox) or fondaparinux (Arixtra)
  • Direct thrombin inhibitor assay (to assess bivalrudin or argatroban effect)
  • Dabigatran (Pradaxa) – uses dilute thrombin time assay
  • Rivaroxaban (Xarelto) – uses anti‑Xa assay
  • Apixaban (Eliquis) – uses anti‑Xa assay
  • VerifyNow assay to assess resistance to therapy with clopidogrel (Plavix), prasugrel (Effient) or aspirin.

Testing for Heparin‑Induced Thrombocytopenia

  • Enzyme‑linked immunoassay for heparin‑PF4 IgG antibodies.
  • Reflexive serotonin release assay (sendout test) after positive heparin‑PF4 antibody test.


  • Measure the mechanical properties of a developing blood clot and the efficiency of blood coagulation in whole blood.

Group/Panel Testing

  • Anti-phosphlipids group/cardiolipins: Includes Anti‑Beta‑2‑glycoprotein‑1, Anti‑cardiolipins, IgA, IgG, IgM
  • Lupus anticoagulant: Includes Lupus Inhibitor, Antiphospholipid Group/Cardiolipins
  • Von Willebrand disease group: Includes Von Willebrand Factor Antigen, Factor VIII Activity, Von Willebrand Factor Multimer and VWF Collagen Binding
  • Thrombosis panels
    • Venous: Includes Activated Protein C Resistance, Antithrombin, Protein C Activity, Protein‑S Free Antigen, and Lupus Inhibitor
    • Comprehensive venous: includes Venous Panel, chromogenic factor VIII, C‑reactive protein, and Prothrombin DNA screen.


Coagulation welcomes collaboration with researchers. Testing available includes clinical testing as above, as well as non‑clinical research‑only testing (such as PIVKA II, Thrombin/Antithrombin, Prothrombin Fragment 1.2 , Human p‑Selectin). Please contact laboratory for more information.


The Clinical Coagulation Division participates in training programs for undergraduate medical laboratory science students, medical students, clinical pathology residents and hematopathology fellows. In addition, a Master of Science in Laboratory Medicine degree is offered with concentration in the Clinical Coagulation area. Please see Education section for more information.


University of Washington Clinical Coagulation Lab
1959 NE Pacific Street, room NW220
Seattle, WA 98195
Tel: 206.598.6242

Harborview Medical Center Clinical Coagulation Lab
325 9th Ave, room GWH 47
Seattle, WA 98195
Tel: 206.744.3128