The Use of Iopamidol, A New Nonionic Contrast Agent, in Lower Limb Phlebography

ABSTRACTContrast phlebography is the best available means of diagnosing deep vein thrombosis of the lower extremities. This test is reliable and safe, but in a certain percentage of cases, side effects occur, such as discomfort during the procedure, a syndrome resembling superficial phlebitis of the lower calf 2 to 12 hours subsequently, and frank postphlebographic thrombosis one to five days later. We have previously assessed the incidence of these complications, using a standard contrast agent (Renografin-60) and the same contrast diluted to three-quarters strength. In the study reported here, we examined the incidence of side effects with iopamidol, a new nonionic contrast agent. Twenty-five patients have been studied to date. Eighteen of these had negative phlebograms initially and were followed with 125I-labeled fibrinogen scanning. None of the 25 patients experienced more than mild discomfort during the phlebogram and none developed the postphlebography syndrome. In contrast, 30% of patients studied with dilute Renografin experienced moderate or marked discomfort during the study and 7.5% developed the postphlebography syndrome. One patient studied with iopamidol developed a positive scan (6%), compared with 9% with dilute Renografin. None of the patients in the current study developed postphlebographic thrombosis, whereas 9% of those receiving dilute Renografin did. We conclude that iopa-midol, at a concentration of 200 mg I/ml, produces contrast phlebograms of good diagnostic quality and is both subjectively and objectively preferable to currently available ionic contrast agents.