Intraperitoneal

Refers to structures inside the peritoneum, the serous membrane that forms the lining of the abdominal cavity.

Intraperitonal structures include: the stomach, first part of the duodenum [5 cm], jejunum, ileum, cecum, appendix, transverse colon, sigmoid colon, rectum (upper 1/3), liver, spleen, and the pancreas (only tail).

Structures that are intraperitoneal are generally mobile, while those that are retroperitoneal are relatively fixed in their location.