Lower extremity venography with iohexol: results and complications

Deep-vein thrombosis (DVT) of the legs occurs when blood clots form in the veins of the legs. Preoperative diagnosis is required to locate and characterize these clots. This is usually done using venography, a technique for X-raying veins. Venography requires the injection of a contrast material to help visualize the clot. These contrast materials can cause side effects, including the development of blood clots in the veins. There are two main types of contrast materials, high-osmolar and low-osmolar. Studies have shown that the high-osmolar materials are more likely to cause side effects. This study examined the use of the low-osmolar, nonionic material, iohexol, to evaluate its effectiveness and to determine the amount and kinds of side effects it produced. Venography using iohexol was performed on 463 patients. They were subsequently examined for side effects. Eighty-three patients reported minor side effects including pain in the foot, nausea, dizziness, edema (accumulation of fluids in tissues), and itching. Two patients suffered serious side effects (bronchospasm, a spasm of the airways). A subset of 41 patients were examined for fibrinogen uptake as an indicator of blood clot formation. Although 10 of these patients tested positive, further examination showed that only one patient had formed new clots. The results reported here were comparable to those of previous studies showing a low incidence of blood clot formation when low-osmolar materials were used, and the incidence of new blood clots was much lower than has been reported with high-osmolar contrast agents. Iohexol was associated with less discomfort than many of the other materials used. These results indicate that iohexol is a safe and effective contrast material for use in venography. (Consumer Summary produced by Reliance Medical Information, Inc.)