The incidence of postoperative deep vein thrombosis.

A prospective study of the incidence of deep vein thrombosis in surgical patients was carried out in 130 general surgical patients, undergoing a major elective operation requiring a general anaesthetic of more than 30 minutes' duration and followed by at least 7 days in hospital. An additional 23 neurosurgical cases, 31 ophthalmic and otorhinolaryngology patients and 7 renal transplant recipients were studied.All patients were screened with radioactive fibrinogen employing a Pitman ratemeter and with Doppler ultrasonography, and 32 patients with positive results were examined by bilateral ascending venography. The incidence of deep vein thrombosis by these criteria in the general surgical patients was 51%. In 76% of cases, it was apparent within 72 hours of surgery and bilateral in 64% of cases. The calf alone was involved in only 43% of cases, and more proximal extension occurred in the remaining 57%. Venography confirmed the diagnosis of deep vein thrombosis in 29 of 32 patients tested. Objective clinical evidence of venous thrombosis was present in only 3.8% of the positive cases, but the subjective symptom of pain in the calf was present in 29% of positive cases. The incidence of positive cases in neurosurgical patients was 43%, in ophthalmology and otorhinolaryngological patients 6%, and in renal transplant patients 57%