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The retroperitoneum is the anatomical space in the abdomen that lies posterior to the parietal peritoneum and anterior to the transversalis fascia. It contains vital vascular, lymphatic, renal, adrenal, and gastrointestinal structures.

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Retroperitoneal space and Retroperitoneal organs

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![Illustration of the retroperitoneum at the level of the kidneys demonstrating the retroperitoneal compartments (PP: Parietal peritoneum, APF: Anterior pararenal fascia, LCF: Lateroconal fascia, APS: Anterior pararenal space, PRS: Perirenal space, PPS: Posterior pararenal space, RRS: Retrorenal space, PPS, TF: Transversalis fascia).

Montanarella M, Gonzalez Baerga CI, Menendez Santos MJ, Elsherif S, Boldig K, Kumar S, et al. Retroperitoneal anatomy with the aid of pathologic fluid: An imaging pictorial review. J Clin Imaging Sci. 2023;13:36. doi: 10.25259/JCIS_79_2023](attachment:c4014f38-ccfd-4716-985c-048656eb0ad0:JCIS-13-36-g001.png)

Illustration of the retroperitoneum at the level of the kidneys demonstrating the retroperitoneal compartments (PP: Parietal peritoneum, APF: Anterior pararenal fascia, LCF: Lateroconal fascia, APS: Anterior pararenal space, PRS: Perirenal space, PPS: Posterior pararenal space, RRS: Retrorenal space, PPS, TF: Transversalis fascia).

Montanarella M, Gonzalez Baerga CI, Menendez Santos MJ, Elsherif S, Boldig K, Kumar S, et al. Retroperitoneal anatomy with the aid of pathologic fluid: An imaging pictorial review. J Clin Imaging Sci. 2023;13:36. doi: 10.25259/JCIS_79_2023

![Illustration of the retroperitoneal space at and below the level of kidneys.

Montanarella M, Gonzalez Baerga CI, Menendez Santos MJ, Elsherif S, Boldig K, Kumar S, et al. Retroperitoneal anatomy with the aid of pathologic fluid: An imaging pictorial review. J Clin Imaging Sci. 2023;13:36. doi: 10.25259/JCIS_79_2023](attachment:66ea99a0-415c-4b68-b0dc-588645351d31:JCIS-13-36-g002.png)

Illustration of the retroperitoneal space at and below the level of kidneys.

Montanarella M, Gonzalez Baerga CI, Menendez Santos MJ, Elsherif S, Boldig K, Kumar S, et al. Retroperitoneal anatomy with the aid of pathologic fluid: An imaging pictorial review. J Clin Imaging Sci. 2023;13:36. doi: 10.25259/JCIS_79_2023

Boundaries

Anterior Posterior parietal peritoneum.
Posterior Transversalis fascia and vertebral column.
Superior Diaphragm
Inferior Pelvic brim (continuous with extraperitoneal pelvis)
Lateral Lateroconal fascia

Compartments

The retroperitoneum is divided into three main compartments:

Compartments Boundaries Contents
Anterior pararenal space (APS) • Anterior: Posterior parietal peritoneum.
• Posterior: Anterior renal (Gerota’s) fascia. • Pancreas.
• Duodenum (2nd–4th parts).
• Ascending & descending colon.
• Vessels (superior mesenteric vessels, gonadal vessels).
Perirenal space (PRS) Between anterior (Gerota’s) and posterior (Zuckerkandl’s) renal fascia. • Kidneys, adrenal glands.
• Proximal renal vessels.
• Proximal collecting system.
• Fat.
Posterior pararenal space (PPS) • Anterior: Posterior renal fascia (Zuckerkandl’s).
• Posterior: Transversalis fascia. Only fat, no solid organs.

Other related compartments:

Pathology

Inflammatory Retroperitoneal fibrosis, pancreatitis-related collections.
Neoplastic Lymphoma, sarcoma, germ cell tumors, metastases.
Vascular Aortic aneurysm, retroperitoneal hematoma.
Infective Abscess (e.g., psoas abscess).