RENAL TRAUMA AND PREEXISTING UPJ OBSTRUCTIONS:IS THERE A RELATIONSHIP TO UPJ DISRUPTION?

INTRODUCTION AND OBJECTIVE: It has been hypothesized that patients with preexisting ureteropelvic junction (UPJ) obstruction who sustain blunt renal trauma are at greater risk of high grade renal injuries and UPJ disruption. We investigated if patients with preexisting UPJ obstruction sustaining a traumatic insult have a higher incidence of high grade renal injuries. METHODS: A retrospective review of patients with pre-existing UPJ obstruction who sustained a traumatic insult requiring urologic evaluation was performed. The mechanism of injury, grade of renal injury, surgical management and outcome were recorded. RESULTS: A total of 20 patients (20 kidneys) with a pre-existing UPJ obstruction who sustained a traumatic insult were identified. All patients presented with gross hematuria without associated shock. Radiographic evaluation revealed an isolated renal injury in 18 (90%) patients. Grade I renal injuries were found in 11 (55%). Grade IV or collecting system only injuries were identified in 9 (45%), of whom 5 (55%) had urinary extravasation through thinned parenchyma and 4 (45%) had a collecting system injury without parenchymal injury. None of the patients were found to have a complete disruption of the UPJ as determined by retrograde pyelogram or surgical exploration. Patients were initially managed with temporary drainage in the form of double J ureteral stent plus urethral catheter (n=5), double J stent, urethral catheter and percutaneous nephrostomy (n=3), or percutaneous nephrostomy alone (n=1). All 20 patients underwent surgery. Primary nephrectomy was required in 5 (25%) due to reduced or absent function (n=3) or complete devitalization of the renal pelvis (n=2). The remaining 15 (75%) kidneys were ultimately repaired by dismembered pyeloplasty. All repairs were deemed successful by MAG 3 furosemide renogram performed 3 months postoperatively with median percent function of 35 % (range 25-50%). CONCLUSIONS: In our series, pre-existing UPJ obstruction does not appear to predispose patients to complete UPJ disruption following a traumatic insult. The majority of patients (55%) presenting for trauma evaluation with a pre-existing UPJ obstruction were found to have minor renal injuries. The likelihood of successful surgical repair of the kidney with pre-existing UPJ obstruction following blunt renal trauma is related to pre-existing poor renal function and/or traumatic devitalization of the renal pelvis.