Figure 2From: Gastrointestinal perforation: ultrasonographic diagnosisDirect sign, such localized gas collections related to bowel perforations, may be detectable, particularly if they are associated with other sonographic abnormalities, called indirect signs (thickened bowel loop and air bubbles in ascitic fluid or in a localized fluid collection, bowel or gallbladder thickened wall associated with decreased bowel motility or ileus)Back to article page