Pneumatosis in the descending colon: preliminary observations on the value of prone positioning.

Prone positioning is valuable for accurate diagnosis of intramural air in the descending colon. In the supine position, partial collapse of the descending colon can minic intramural air. Conversely, complete collapse of the descending colon eliminates the interface between intraluminal and intramural air so that the recognition of intramural air is obscured. The tendency for the descending colon to distend with gas in the prone position may reduce these false positives and negatives for intramural air.