Retroperitonealses

Retroperitonealses is a term used here to refer to the retroperitoneal spaces and their contents within the abdomen. The retroperitoneum lies behind the peritoneum, the lining of the abdominal cavity, and extends from the diaphragmatic hiatus to the pelvic brim. It contains structures that are not suspended within the peritoneal cavity, and it is organized into compartments that influence the spread of pathology.

The retroperitoneal space is conventionally subdivided into three main pararenal compartments and a perirenal space. The perirenal (perinephric) space lies within the renal fascia surrounding the kidneys and adrenal glands. The anterior pararenal space lies between the peritoneum and the anterior renal fascia and contains portions of the pancreas (head and body), the second through fourth parts of the duodenum, and the ascending and descending colon. The posterior pararenal space lies between the posterior renal fascia and the transversalis fascia and is largely fat-filled. The aorta, inferior vena cava, sympathetic trunks, and associated lymphatics course through the retroperitoneum, closely related to the kidneys, pancreas, and portions of the gastrointestinal tract.

Contents commonly encountered in retroperitonealses include the kidneys, adrenal glands, proximal ureters, portions of the pancreas and duodenum, ascending and descending colon, the aorta, the inferior vena cava, and surrounding fat and connective tissue. Nerves from the renal, aortic, and lumbar plexuses contribute to its innervation.

Clinical relevance centers on trauma, hemorrhage, infection, and neoplasms that originate or spread within the retroperitoneal spaces. Imaging—particularly CT and MRI—plays a key role in localization and assessment. Understanding the compartmental organization aids in diagnosing disease extent and planning surgical approaches, such as access to retroperitoneal tumors or management of retroperitoneal fluid collections.