Low-dosage ancrod for prevention of thrombotic complications after surgery for fractured neck of femur.

The effect of a low-dosage regimen of ancrod in the prevention of postoperative deep vein thrombosis was assessed in 24 patients having surgical repair of fractured neck femur and compared with 25 control patients who did not receive therapy. The objective of the therapy was to lower the preoperative fibrinogen level and produce a low concentration of fibrin degradation products yet avoid the haemorrhagic complications of total defibrination. Ancrod therapy proved feasible to carry out, was not associated with haemorrhagic complications, and produced sustained, predictable reductions in fibrinogen concentration. There were seven thromboembolic complications in the control patients compared to one such complication in the ancrod-treated patients. Five deaths occurred in the control group and one in the treated group. Though the incidence of deep vein thrombosis was not apparently affected by ancrod it appeared on venography that the thrombi in the treated patients were less extensive than those in the control patients. Finally, some discrepancies in the diagnosis of deep vein thrombosis by the three techniques of clinical examination, (125)I-fibrinogen scanning, and ascending venography were identified.