[Sonographic detection of gas in the vascular system of the liver: an image essay].

Gas within the vascular system of the liver was demonstrated sonographically in 5 patients. In contrast, plain films of the abdomen in these patients failed to demonstrate this serious finding. 3 patients presented with gas within the hepatic portal venous system, 1 patient with gas in the liver veins. In these patients, gas formation was probably caused by sepsis with gas-producing bacteria. In the last patient, air within the hepatic arterial system was caused by insufflation of air thru a port-a-cath catheter located in the main hepatic artery. The characteristic sonographic appearance of intravascular gas are highly echogenic particles flowing within the vessels. Different pathophysiologic mechanisms of gas formation in the hepatic portal venous system include sepsis with gas forming organisms, gastrointestinal necrosis of various origin in combination with elevation of intramural pressure and alteration of gas solubility of blood. The significance of sonography as a very sensitive and specific modality is outlined.