The peritoneum is the largest and most complex serous membrane in the body. It forms a closed sac (ie, coelom) by lining the interior surfaces of the abdominal wall (anterior and lateral), by forming the boundary to the retroperitoneum (posterior), by covering the extraperitoneal structures in the pelvis (inferior), and by covering the undersurface of the diaphragm (superior). This parietal layer of the peritoneum reflects onto the abdominal visceral organs to form the visceral peritoneum. It thereby creates a potential space between the two layers (ie, the peritoneal cavity).
The peritoneum consists of a single layer of flattened mesothelial cells over loose areolar tissue. The loose connective tissue layer contains a rich network of vascular and lymphatic capillaries, nerve endings, and immune-competent cells, particularly lymphocytes and macrophages. The peritoneal surface cells are joined by junctional complexes, thus forming a dialyzing membrane that allows passage of fluid and certain small solutes. Pinocytotic activity of the mesothelial cells and phagocytosis by macrophages allow for the clearance of macromolecules.
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Peritonitis and abdominal sepsis. Diagnostic and therapeutic approach to peritonitis and peritoneal abscess.
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Peritonitis and abdominal sepsis. A 48-year-old man underwent suprapubic laparotomy, right hemicolectomy, and gastroduodenal resection for right colon cancer invading the first portion of the duodenum. After surgery, the patient developed abdominal pain and distention. Computed tomography (CT) scanning was used to confirm an anastomotic dehiscence. Figure A shows a contrast-enhanced scan of the abdomen and pelvis that reveals multiple fluid collections, perihepatic ascites, and mild periportal edema. A collection of fluid containing an air-fluid level is visible anterior to the left lobe of the liver. A second collection is anterior to the splenic flexure of the colon. In figure B, a third fluid collection is present in the inferior aspect of the lesser space and in the transverse mesocolon. Figure C shows the pelvis with a collection of free fluid in the rectovesical pouch.
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Peritonitis and abdominal sepsis. A 78-year-old man was admitted with a history of prior surgery for small bowel obstruction and worsening abdominal pain, distended abdomen, nausea, and obstipation. In figure A, a marked amount of portal venous gas within the liver, mesenteric venous gas, and pneumatosis intestinalis are consistent with ischemic small intestine. The superior mesenteric artery appears patent. The liver has a nodular contour consistent with cirrhosis. In figures B and C, markedly distended loops of small intestine containing fluid and air-fluid levels are consistent with a small bowel obstruction. No focal fluid collections are identified.
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Peritonitis and abdominal sepsis. A 35-year-old man with a history of Crohn disease presented with pain and swelling in the right abdomen. In figure A, a thickened loop of terminal ileum is evident adherent to the right anterior abdominal wall. In figure B, the right anterior abdominal wall is markedly thickened and edematous, with adjacent inflamed terminal ileum. In figure C, a right lower quadrant abdominal wall abscess and enteric fistula are observed and confirmed by the presence of enteral contrast in the abdominal wall.
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Peritonitis and abdominal sepsis. Gram-negative Escherichia coli.
