"pneumoperitoneum: free intraperitoneal gas that is best seen in the lung window. A careful search for extraluminal gas should be done as the amount is occasionally minimal especially in the early disease and small perforations."
"leakage of oral contrast into the peritoneal cavity: it is highly specific for perforation; however, its sensitivity is low. Small perforations are usually not associated with significant oral contrast leakage. Moreover, some perforation sites require a specific patient position to demonstrate oral contrast leakage like right lateral decubitus for duodenal perforations."
"duodenal perforation during ERCP: the perforation is usually retroperitoneal with free gas seen at the anterior pararenal space, rarely extending intraperitoneal. If an injury is suspected during the procedure, non-enhanced CT is recommended after, for detection of the leakage of contrast used during the procedure."
"bowel perforation secondary to ischaemia and gangrene: associated with pneumatosis intestinalis, portal venous gas, free intraperitoneal fluid, and pneumoperitoneum. Multiphasic contrast-enhanced CT is usually capable of detection of the culprit diseased vessel."
"Findings specific for different aetiologies"
"duodenal perforation during ERCP: the perforation is usually retroperitoneal with free gas seen at the anterior pararenal space, rarely extending intraperitoneal. If an injury is suspected during the procedure, non-enhanced CT is recommended after, for detection of the leakage of contrast used during the procedure."
Expected headings
"Technique"
"CT findings"
"leakage of oral contrast into the peritoneal cavity: it is highly specific for perforation; however, its sensitivity is low. Small perforations are usually not associated with significant oral contrast leakage. Moreover, some perforation sites require a specific patient position to demonstrate oral contrast leakage like right lateral decubitus for duodenal perforations."
"precise detection of the perforation site: is usually difficult. Some helpful signs include; localised bowel wall thickening or focal bowel wall interruption with adjacent free gas bubbles and localised dirty mesenteric fat. The presence of pneumoperitoneum on both sides of the falciform ligament favours the possibility of proximal rather than distal bowel perforations"