What is the anatomy of the peritoneum relevant to peritonitis and abdominal sepsis?

Updated: Jul 23, 2019
  • Author: Brian J Daley, MD, MBA, FACS, FCCP, CNSC; Chief Editor: Praveen K Roy, MD, AGAF  more...
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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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