Nonionic contrast media in radiology. Procedural considerations.

Reports of thrombus formation or embolism during angiography with nonionic contrast media were reviewed. Several factors were identified that may contribute to blood clot formation within or on the surface of angiographic catheters. Nonionic contrast media have a mild anticoagulant effect in vitro and in vivo. Careful and correct angiographic techniques are necessary to effectively use the nonionic contrast substances. As a basic principle, blood should not be mixed with the contrast agent prior to intravascular injection. Frequent flushing of the angiographic catheter with heparinized saline is recommended.