Duplex venous scanning for the prospective surveillance of perioperative venous thrombosis

A total of 361 patients undergoing a variety of major neurosurgical procedures were entered into a prospective surveillance program using duplex ultrasound scanning for detection of perioperative deep venous thrombosis (DVT). All patients had duplex scans of the major veins of both legs preoperatively, on the third and seventh postoperative days, and at weekly intervals thereafter if hospitalized. All patients received elastic stocking and intermittent mechanical calf compression. Perioperative DVT was diagnosed by duplex scan in 17 cases (4.7%); 2 cases were present preoperatively and the remaining 15 cases developed after surgery. Venography detected only one false-positive scan in this series. One patient with DVT died, but the postmortem examination revealed no pulmonary embolism. The results of serial venous scans were normal in 344 cases. There were no in-hospital pulmonary embolisms in any patient with normal venous scan results. Two patients (0.6%) with normal serial scan results had fatal pulmonary embolism 1 and 3 weeks after discharge. Duplex venous scanning was useful for prospective DVT surveillance of a high-risk group. The overall incidence of DVT (4.7%) is below that expected in such patients, suggesting the effectiveness of the program of prophylaxis. Scan results were reliable for therapeutic decisions and did not jeopardize patient safety.