Ultrasonographic appearance of gas-containing abscesses in the abdomen.

This report describes the sonographic appearance of six gas-containing abdominal abscesses. Gas-containing abscesses may appear as densely echogenic masses with acoustical shadowing, but may also be seen merely as regions of acoustical shadowing or as an echogenic mass. A hypothesis is advanced that the appearance of gas-containing abscesses as echogenic masses may be due to a "microbubble" constrast effect.