The retroperitoneum is the part of the abdominal cavity that lies between the posterior parietal peritoneum anteriorly and the posterior abdominal wall 4. It is C-shaped on axial cross-section with convexity projecting anteriorly in the mid-line.
Gross anatomy
The retroperitoneum is variably defined, mostly by the lack of consensus definition for the posterior abdominal and whether the psoas muscles and quadratus lumborum are boundaries or contents 4. It can have up to five compartments depending on definition:
-
lateral compartments divided into three spaces by renal fascia 4
great vessel compartment: from T12 to L4/5 between perirenal space 2,3
posterior compartment: containing psoas muscles, which join iliacus behind transversalis fascia, quadratus lumborum 4
Perirenal space
inverted cone shape with base resting on diaphragm and point directing towards the pelvis
-
boundaries
-
anterior and posterior renal fascia continuous with each other (fascia of Gerota and Zuckerkandl respectively)
anterior renal fascia blends anteriorly with connective tissue around aorta and inferior vena cava
-
posterior renal fascia (thicker, two lamina) blends with quadratus lumborum fascia
superficial lamina is made up of lateroconal fascia which extends anteriorly and attaches to peritoneum
-
contents : kidney, adrenal gland, renal pelvis, proximal ureter, renal hilar vessels, lymph nodes, fat
-
relations
upper right perirenal space communicates with retrohepatic space at bare area of the liver
posterior pararenal space related posteriorly
anterior pararenal space related anteriorly
the Kneeland space is a theoretical communication between both perirenal spaces, anterior to the aorta and inferior vena cava
Anterior pararenal space
boundaries: posterior parietal peritoneum anteriorly, anterior renal fascia posteriorly and lateroconal fascia (continuation of posterior renal fascia) laterally
contents: duodenum (D2-D4), ascending and descending colon, pancreas, lymph nodes, fat
relations: potentially continuous across mid-line, intraperitoneal space anteriorly, perirenal space posteriorly
Posterior pararenal space
boundaries: posterior renal fascia anteriorly, transversalis fascia posteriorly
contents: fat
-
relations
communicates with properitoneal space in the anterior abdomen between peritoneum and transversalis fascia
communicates potentially with contralateral side
communicates with flank laterally (external to lateroconal fascia and deep to transversalis fascia); visualized as flank strip radiologically
opens inferiorly towards pelvis following length of ureter
Great vessel compartment
not well-defined by fascial planes
-
boundaries
laterally: perirenal space and ureter
posteriorly: vertebral body, psoas major muscle
superiorly: continuous with the posterior mediastinum
contents: aorta, inferior vena cava, fat, lymph nodes