Laboratory Investigation of an Inherited Bleeding Tendency

April 15, 2016

The laboratory investigation of a possible bleeding tendency should be guided by a comprehensive review of the patient's bleeding (and medical) history and by the findings of a thorough physical evaluation.

The duration of the bleeding problem (life-long versus recent onset), type of bleeding (mucocutaneous versus deep tissues bleeding), medication history and family history all provide important information that assist the pathologist in interpreting aboratory results.

Detailed assessment of a patient's life-long bleeding history using the bleeding assessment tool recommmended by the International Society on Thombosis and Haemostasis will provide invaluable information and is strongly encouraged.

Physical evaluation may reveal signs of liver disease, nutritional deficiencies or other medical conditions like lymphoproliferative or autoimmune diseases that are often associated with secondary bleeding tendencies.

Download: Laboratory investigation of an inherited bleeding tendency.

If a strong suspicion of a bleeding tendency exists, platelet count and platelet morphology are important to exclude a primary haemostasis disorder. The very basic coagulation screening tests such as the prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin clotting time (TCT) and/or fibrinogen should also be performed initially. 

Normal results would usually exclude quantitative defects in the platelets and the intrinsic and extrinsic factors of the coagulation pathway but will not exclude disorders of platelet function, von Willebrands disease, F XIII deficiency, and some rarer conditions (e.g. fibrinolytic pathway abnormalities).

As von Willebrand disease (VWD) is the most common inherited bleeding disorder, it is routinely screened for as part of the first-line investigation. For females in the reproductive years, screening for VWD should ideally be performed in the first few days of the menstrual cycle, when von Willebrand factor levels (VWF) are least affected by hormonal fluctuations. One normal result does not fully exclude the disease - for this reason, the World Health Organisation recommends repeat testing on two more occasions. If the VWF screening tests are abnormal, further tests will be recommended by the haematologist in order to classify the VWD subtype or to to measure the response to DDAVP.

If VWD is excluded, the next step would be to rule out a platelet function defect. The PFA-200 screening analysis is recommended at the time of the second VWF screening test as it is also quite sensitive for identifying VWD. Depending on the PFA findings, platelet aggregation studies may be recommended by the haematologist to exclude other possible platelet function defects.

Finally, for patients in whom no quantitative or qualitative and/or coagulation factor defect (including VWD) is identified, the fibrinolytic pathway problems or Factor XIII deficiency may warrant consideration. Tests for these should be arranged in collaboration with both clinical and laboratory haematologists.

Authored by Dr Johan  Niemann, Director of Haematology

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