Stone Formation from Nonabsorbable Clip Migration into the Collecting System after Robot-Assisted Partial Nephrectomy

We describe a case in which a Weck Hem-o-lok clip (Teleflex, Research Triangle Park, USA) migrated into the collecting system and acted as a nidus for stone formation in a patient after robot-assisted partial nephrectomy. The patient presented 2 years postoperatively with left-sided renal colic. Abdominal computed tomography scan showed a 10 millimeter renal calculus in the left middle pole. After using laser lithotripsy to fragment the overlying renal stone, a Weck Hem-o-lok clip was found to be embedded in the collecting system. A laser fiber through a flexible ureteroscope was used to successfully dislodge the clip from the renal parenchyma, and a stone basket was used to extract the clip. 1. Introduction Renorrhaphy is a time-sensitive and technically challenging aspect of robot-assisted partial nephrectomy (RPN). As such, the sutures used for kidney closure are commonly secured in place with a surgical clip [1], rather than conventional knot tying. A rare postoperative complication associated with this technique is migration of the surgical clip into the urinary tract, which may cause significant morbidity for patients [2–4]. Herein, we describe a case in which a Weck Hem-o-lok clip (Teleflex, Research Triangle Park, USA) migrated into the collecting system and acted as a nidus for stone formation after RPN. 2. Case Report A 52-year-old man with a history of nephrolithiasis and prostate cancer after robot-assisted radical prostatectomy presented with a small left renal mass. Abdominal computed tomography (CT) scan with and without contrast showed an enhancing 3 centimeter (cm) left middle pole renal mass that was noted to have increased in size since a prior CT scan. Subsequently, the patient underwent an uneventful left RPN. The renorrhaphy was completed in a single layer using a running 3-0 Vicryl (Ethicon, Somerville, USA) suture which was secured in place with Weck Hem-o-lok clips using sliding clip technique. Hemostasis was achieved without the use of any hemostatic agents or bolsters. The patient’s postoperative course was complicated by a perinephric hematoma that was diagnosed by CT scan. Renal angiography was negative for active bleeding, and the patient was managed with blood transfusions and close observation in the intensive care unit. Pathology indicated a 2.4？cm clear cell renal cell carcinoma, Fuhrman grade II, and negative surgical margins. Two years after RPN, the patient presented with left-sided colicky flank pain. Noncontrast helical abdominal CT scan showed a 6 millimeter (mm) left ureteral stone and a 10？mm left middle pole