Pelvic hydronephrotic kidney masquerading as obstructed bowel

Abstract

A 6 year-old boy presented to an outlying hospital with a 4-day history of abdominal discomfort, constipation, and emesis. An initial computed tomography scan of his abdomen was done without intravenous contrast, and the findings were initially believed to represent a small bowel obstruction (Fig. 1A; see next page for figures). He was referred to our institution for additional treatment. The physical examination revealed a blood pressure of 142/103 mm Hg and a firm lower abdominal mass. The serum creatinine was 0.8 mg/dL. Contrast-enhanced computed tomography of the abdomen and pelvis was performed to delineate the patient’s abnormality more clearly. This revealed the absence of an orthotopic left kidney (Fig. 1B) and a large left ectopic kidney (Fig. 2A), with contrast pooling in the collecting system on delayed images (Fig. 2B). Most ectopic kidneys are asymptomatic and discovered incidentally. However, in a retrospective series, Gleason et al.1 reported that one quarter of 77 patients presenting with renal ectopia were initially evaluated for gastrointestinal complaints. When an orthotopic kidney is not identified, a high index of suspicion for ectopia should guide the imaging choices. Although a variety of imaging modalities can appropriately suggest the diagnosis, contrast-enhanced computed tomography can verify the diagnosis if the ectopic kidney exhibits function.