Diagnosis: Crossed Fused Renal Ectopia

History: History of diverticulitis with recent removal of sigmoid colon and colostomy. No history of urologic complaints or problems.

Findings: CT revealed ill-defined mixture of soft tissue and air in the periumbilical region in the post-operative site. This in combination with the patient's history and physical exam are highly suggestive of an infection. The notable other finding on CT scan was the absence of a kidney in the right retroperitoneal space. Further inspection, however, revealed two left kidneys but also a distal right ureter with normal bladder insertion.

Ddx: The differential of an absent retroperitoneal kidney. 1) Congenital absence of the kidney 2) S/P nephrectomy 3) Renal ectopia (pelvic kidney, crossed fused ectopia, intrathoracic kidney)

Dxhow: CT findings

Exam: On physical exam, the patient's colostomy site was noted to be erythematous and tenderness to palpation. Laboratory tests were significant for an elevated white blood cell count.