Julia R. Fielding, M.D. Brigham and Women's Hospital, Harvard Medical School Boston, Massachusetts

Obstruction of the Upper Pole Moiety of a Duplicated System Diagnosed Using Spiral CT

This 42 year-old man status post abdominoperineal resection for adenocarcinoma of the colon presented with right flank pain. Thin-section (5mm) non contrast-enhanced spiral CT demonstrates duplication of the right intrarenal collecting system with obstruction of the upper pole moiety manifested by severe hydronephrosis and cortical thinning (Figure 1) and a non-obstructed lower pole moiety (Figure 2). An image through the pelvis (Figure 3) shows a large stone within a dilated and posteriorly displaced ureter. Supine radiograph of the abdomen (Figure 4) confirms presence of the stone. As no ectopic insertion site for the dilated ureter could be identified, intraoperative transabdominal ultrasound was used to guide the cystoscope to the level of the stone (Figure 5). An incision was made in the posterior wall of the bladder and the stone removed through it.