Perirenalis

Perirenalis, or perirenal, refers to structures and spaces surrounding the kidney. In human anatomy, the primary region is the perirenal space within the retroperitoneum, enclosed by the renal fascia, traditionally called Gerota’s fascia, which has anterior and posterior leaves that surround the kidney and adrenal gland.

Anatomy and boundaries: The kidney is surrounded by a fibrous capsule and a layer of perinephric fat, both of which lie inside the renal fascia. The perirenal space is the potential space between the renal capsule and Gerota’s fascia, extending from the superior to the inferior poles of the kidney and projecting into the upper abdomen. The fasciae bound the space anteriorly and posteriorly, with lateral continuity to the transversalis fascia; medially, the space abuts adjacent retroperitoneal structures such as the psoas major and great vessels.

Contents and relations: The perirenal space contains the kidney, the adrenal gland, perinephric fat, renal vessels, nerves, and accompanying lymphatics. The surrounding fascia serves to contain infection, hemorrhage, or fluid collections within this compartment.

Clinical relevance: Pathology in the perirenal space includes perirenal abscess and hematoma, often related to trauma, infection, or coagulopathy. Urine leaks from the collecting system or trauma can form a urinoma within this space. Tumors can involve or extend into the perirenal space, and spread to adjacent spaces may indicate more extensive disease.

Imaging and diagnosis: Cross-sectional imaging, especially CT and MRI, delineates the perirenal space, its contents, and whether Gerota’s fascia is breached, guiding management. Ultrasound is useful for detecting sizable collections in some patients. Management is etiologically dependent, ranging from drainage of collections to observation for resolving fluid accumulations.