Blood clotting is a complex process involving the interaction of many substances in the blood that promote coagulation. A deficiency of any of these substances results in a bleeding disorder. Some disorders are inherited (hemophilia, for example) and some (such as liver disease) are acquired. A common disorder associated with cancer is a low platelet count (thrombocytopenia), which sometimes results from chemotherapy or radiotherapy and may make platelet transfusions necessary until the process subsides. Sophisticated tests are often needed to diagnose bleeding disorders.
