Clinical Information

When coagulation screening tests are performed to verify normal function of the coagulation system (eg, preoperative, routine examination), they sometimes indicate an abnormality that may be unexplained (ie, prolonged clotting times). This consultation provides validation of the prolongation and as comprehensive a workup as needed to define the abnormality.

Possibilities for a cause of prolongation include:

-Artifactual due to high hematocrit (dilution of specimen by anticoagulant if patient hematocrit is 55% or greater)

-Factor deficiencies, congenital or acquired

-Factor inhibitors eg, factor VIII inhibitors (bleeding disorder)

-Lupus anticoagulant (risk for thrombosis or recurrent miscarriage)

-Anticoagulant drug effect eg, (including warfarin [Coumadin or Jantoven], oral anti-Xa inhibitors, oral direct thrombin inhibitors), heparin.