Coagulation Time/ Clotting Time (CT)

Coagulation Time/ Clotting Time (CT)

Normal range

 6 –17 minutes (glass tube),

Indications and Interpretations         

Former routine method for control of heparin therapy but now replaced by a partial thromboplastin time(PTT) as it is not a reliable screening test for bleeding conditions because it is not sensitive enough to detect mild conditions but only detects severe ones; normal coagulation time does not rule out a coagulation defect; routine preoperative bleeding and coagulation time are of  little value for preoperative screening.

Prolonged in

Severe deficiency (< 6%) or any known plasma clotting factors except factor XII and factor VII, afibrinogenemia and presence of circulating anticoagulant (including heparin).

Normal in

Thrombocytopenia, deficiency of factor VII, von Willebrand's disease, and mild coagulation defects due to any causes.