Fig. 9

Duodenal perforation complicating ERCP in a 60-year-old man. Contrast-enhanced CT scan at the level of right renal hilum (a, b) and iliac crest (c) shows the retroperitoneal and interfascial planes. a Anterior pararenal space (APS) is limited by posterior parietal peritoneum and anterior renal fascia, with midline continuity; posterior pararenal space (PPS) between posterior renal fascia and transversalis layer of endoabdominal fascia; perirenal space (PS) between anterior and posterior renal fascias. Renal and lateroconal fasciae are laminated, defining potential spaces: the retromesenteric (RMP), the retrorenal (RRP) and lateroconal planes (LP) that all communicate at fascial trifurcation. b Axial image focused on fascial trifurcation. Ectopic gas is seen extending through the retromesenteric plane (RMP), retrorenal plane (RRP) and lateroconal plane (LP), and meeting at the fascial trifurcation (red star). Posterior pararenal space (PPS) anteriorly continues as a fat stripe in the properitoneal space (PP). c Inferior extension of the interfascial plane, delineated by ectopic gas/air. The retromesenteric and the retrorenal planes approximate one another as the fat cone of perirenal fat diminishes inferiorly, resulting in the combined interfascial plane (CIP); it continues in the pelvis along the anterolateral margins of the psoas muscle contiguous with the pelvic retroperitoneal perivesical and presacral spaces