To identify patients who fail intermittent pneumatic compression and who might be considered for other more intense thromboembolic prophylaxis.We conducted a retrospective review of consecutive gynecologic surgery patients treated with intermittent pneumatic compression. Risk factors associated with thromboemboli and demographic data were reviewed. Clinical suspicion of thromboemboli was confirmed by established diagnostic techniques such as duplex Doppler ultrasound and ventilation perfusion scanning. The association between individual risk factors and the incidence of thromboemboli was identified. To control for confounding of variables, multivariable stepwise logistic regression analysis was performed.A total of 1862 patients undergoing gynecologic surgery between 1996 and 1997 were treated perioperatively with intermittent pneumatic compression. The overall incidence of postoperative thromboemboli was 1.3% (15 cases of clinically significant postoperative pulmonary emboli and nine deep venous thrombosis). Risk factors associated with the occurrence of thromboemboli were: cancer (P =.001), history of deep venous thrombosis (P =.03), hypertension (P =.05), use of antihypertensives (P =.04), and age at least 60 years (P =.002). Intraoperative risk factors included duration of anesthesia more than 3 hours (P =.05). The multivariable regression analysis found that the diagnosis of cancer (P =.001), history of deep venous thrombosis (P =.006), and age greater than 60 years (P =.04) were independent prognostic factors. Patients with two or three of these variables had a 3.2% incidence of developing thromboemboli as compared with a 0.6% incidence of thromboemboli if the patient had none or one risk factor. Patients most likely to fail intermittent pneumatic compression prophylaxis include those with cancer, a past history of deep venous thrombosis, or who are 60 years or older. This information identifies a "higher-risk" group of patients who should be considered for more intense prophylaxis programs.