Narrowing of the upper abdominal inferior vena cava in patients with elevated intraabdominal pressure: sonographic observations.

Focal narrowing of the upper intrahepatic inferior vena cava on computed tomography performed in patients with elevated intraabdominal pressure has been reported recently. The purpose of this study was to assess this phenomenon further with gray scale and duplex Doppler sonography. Seven patients with elevated intraabdominal pressure due to massive ascites in whom computed tomography showed narrowing of the intrahepatic inferior vena cava were studied. Sonography confirmed focal narrowing of the intrahepatic inferior vena cava that persisted throughout the respiratory and cardiac cycles. The narrowed inferior vena cava segment had a characteristic slitlike appearance on transverse images, slightly oblique to the sagittal plane. A focal flow jet typical of stenosis was observed in the three patients in whom Doppler sonography technically was feasible. In three of four patients who were able to sit or to turn into the left lateral decubitus position, the narrowing immediately resolved after the positional change but promptly recurred upon return to the supine position. In patients with elevated intraabdominal pressure, focal slitlike narrowing of the intrahepatic inferior vena cava is an anticipated finding that should not be misinterpreted as evidence of stenosis of the inferior vena cava or of a juxtacaval liver lesion.