intraperitoneal

Intraperitoneal refers to anything located within the peritoneal cavity, the potential space in the abdomen bounded by the parietal peritoneum and the visceral peritoneum that covers many abdominal organs. The peritoneum consists of a serous membrane with two layers: the visceral layer lining organs and the parietal layer lining the abdominal wall. An intraperitoneal structure is one that lies within this cavity and is connected to the posterior abdominal wall by mesenteries or omenta, allowing some mobility. In contrast, retroperitoneal structures lie behind the peritoneal lining and are only partially covered by peritoneum.

Common intraperitoneal organs include the stomach, liver (on its anterior surface), spleen, jejunum and ileum, transverse colon, sigmoid colon, and the ovaries and fallopian tubes. Portions of some organs, such as the first part of the duodenum, are intraperitoneal, while other portions are retroperitoneal. The exact classification can vary by anatomy and developmental factors.

Clinical relevance: The term intraperitoneal is used in anatomy, radiology, and medicine. Intraperitoneal injection delivers substances directly into the peritoneal cavity and is primarily used in laboratory and certain therapeutic contexts, offering high local exposure with specific risks. Intraperitoneal chemotherapy targets cancers involving peritoneal surfaces, such as ovarian cancer. Peritoneal dialysis is a related therapy in which dialysate is infused into the intraperitoneal space to remove waste.

Imaging and diagnosis: Free intraperitoneal air on radiographs or CT suggests perforation of a hollow organ, while ascites refers to fluid accumulation within the cavity.