Sonography of Gas in the Abdomen: A Help Rather than a Hindrance

Abstract

Although large amounts of gas can obscure visualization of anatomic structures at sonography, smaller amounts of gas can be detected. Sonographically, gas causes “ring-down” or “comet-tail” (dirty-shadowing) artifacts. Sonography can detect pneumoperitoneum, portal and biliary gas, gas in visceral organs, and gasfilled abscesses. Examples of these gas collections are demonstrated with correlative imaging studies for confirmation.