Figure 2.

Traumatic retroperitoneal hematoma. A, A 74‐year‐old man with left renal injury. Computed tomography (CT) image on admission shows hematoma sequentially spreading from perinephric bridging septa (thin dotted white arrows) in the perirenal space (Type II) to the retromesenteric (white thick arrows), retrorenal (black triangles), and lateroconal (white arrowhead) planes. Note that the psoas muscle and quadratus lumborum muscle are located close to the hematoma within the medial part of the retrorenal plane (purple arrows) as well as in panels B and C. B, A 62‐year‐old man with lumbar spine injury. CT image on admission shows massive retroperitoneal hematoma spreading from the medial part of retrorenal plane (purple arrows) (Type IV), resulting from lumbar fracture and lumbar arteries, into the retromesenteric (white thick arrows), lateroconal (white arrowhead), and lateral part of the retrorenal (black triangles) planes and into the subfascial plane, showing the checkmark sign (gold curved arrow). He died from uncontrollable hemorrhage. Note that the hematoma in the retromesenteric plane is closely located to and elevates the duodenum (shown with orange arrow), and that many strands are detected within the posterior pararenal space (thin white arrows) as well as thickened perinephric bridging septa (thin dotted white arrows). C, A 44‐year‐old man with left renal injury. CT image 3 days after injury shows massive retroperitoneal hematoma travelling into the undamaged right retroperitoneum (red dotted arrow) through the retromesenteric plane (white thick arrows) from the perinephric bridging septa (thin dotted white arrows) in the perirenal space (Type II). Hematoma also extends to the retrorenal (black triangles and purple arrow) and lateroconal (white arrowheads) planes. Note bilateral checkmark signs (gold curved arrows) and strands (thin white arrows) in the posterior pararenal space.