Anterior pararenal, perirenal and posterior pararenal spaces
Mnemonic
SAD PUCKER, for the retroperitoneal structures:
- S - Suprarenal (adrenal) glands
- A - Aorta and inferior vena cava
- D - Duodenum, all but the first part
- P - Pancreas, all but the tail
- U - Ureters
- C - Colon, ascending and descending
- K - Kidneys
- E - oEsophagus, the abdominal part
- R - Rectum, the lower two thirds
The two partial exceptions matter: the first part of the duodenum and the tail of the pancreas are intraperitoneal, the latter because it sits in the splenorenal ligament, which is why it is at risk in splenectomy.
Structures that were once mesenteric and later fused to the wall are secondarily retroperitoneal: duodenum, pancreas, and ascending and descending colon.
Expansion
Divided by the anterior and posterior layers of renal (Gerota’s) fascia:
- Anterior pararenal space - between the posterior parietal peritoneum and the anterior renal fascia. Contains the pancreas, the duodenum (second and third parts) and the ascending and descending colon
- Perirenal space - enclosed by Gerota’s fascia. Contains the kidney, adrenal gland, ureter and perirenal fat
- Posterior pararenal space - between the posterior renal fascia and transversalis fascia. Contains fat only, and continues laterally into the properitoneal fat stripe
The clinical value is in localising disease. Pancreatitis fluid tracks in the anterior pararenal space and can dissect down towards the pelvis. A perinephric abscess stays within Gerota’s fascia. Bleeding into the posterior pararenal space, as from a lumbar artery or in anticoagulated patients, produces flank swelling and loss of the psoas shadow.