Clinically suspected deep venous thrombosis of the lower extremities. A comparison of venography, impedance plethysmography, and radiolabeled fibrinogen

To define the utility of new diagnostic approaches in patients with clinically suspected deep venous thrombosis of the lower extremities, 42 legs of 33 patients were studied by fibrinogen labeled with radioactive iodine (¹²⁵I) impedance plethysmography (IPG), and contrast venography. The clinical diagnosis was confirmed in approximately two thirds of the legs and patients. In venogram-positive legs, fibrinogen¹²⁵I was positive in 70%, IPG in 61%, and one of the two in 78%. In venogram-negative legs, fibrinogen¹²⁵I was positive in four (21%) and IPG was negative in all. It was found that the size, age, and location of the thrombus, collateral vein development, heparin sodium therapy, and technical-interpretive choices can influence both IPG and fibrinogen¹²⁵I results. The data demonstrate that the fibrinogen¹²⁵I and IPG procedures can assist physicians in the diagnosis of clinically suspected deep venous thrombosis of the lower extremities. (JAMA237:2195-2198, 1977)