SAFETY AND EFFICACY OF SERIAL IMPEDANCE PLETHYSMOGRAPHY IN THE DIAGNOSIS OF DEEP VEIN THROMBOSIS IN AN URBAN HOSPITAL: AN EXTERNAL VALIDATION STUDY

The clinical diagnosis of deep vein thrombosis (DVT) is unreliable. Impedance plethysmography (IPG) has become accepted as a highly reliable non-invasive method for DVT detection in symptomatic patients.

It has a high sensitivity (95%) and specificity (96%) for proximal vein thrombosis. Studies with impedance plethysmography have however always been carried out in academic hospitals. To evaluate the safety and efficacy of serial impedance plethysmography alone in an urban hospital setting, a prospective study was done in an urban hospital, involving 234 consecutive outpatients with clinically suspected venous thrombosis. IPG was performed on days 1, 2 and 7. If all tesis remained normal the patient was not treated with oral anticoagulants. All patients were followed for 3 months. In 131 of the 234 patients (56%) IPG was repeatedly normal. Of these 131 patients, no patient died from venous thromboembolism during 3 months follow-up, completed in all patients, and no patient returned with signs of pulmonary embolism. One patient (0.8%) returned with objectively documented DVT after two months. In 103 of the 234 patients (44%) the IPG was abnormal. Venography confirmed the diagnosis of deep venous thrombosis in 92%.

It is concluded that serial IPG is a safe and effective method to detect DVT in clinically suspected outpatients, referred to an urban hospital.