Abstract: PD20-12
Sources of Funding: None

Introduction

Minimally invasive partial nephrectomy (MIPN) has become the gold standard for surgical treatment of small renal masses, and techniques have proliferated to decrease ischemia time, prevent complications, and improve outcomes. Dogma mandates that collecting system be closed after tumor excision to prevent postoperative urine leak, but our experience suggests that this step is not necessary, and may actually increase the risk of compromising underlying structures. We report our experience with MIPN without collecting system closure for patients at high risk of urine leak, as determined by parameters described in the urologic literature.

Methods

We reviewed the data for patients over a 10 year period that underwent MIPN, including clinical and radiographic features. We also performed a literature review to identify predictors of postoperative urine leak-defined as persistent drain output or elevated fluid creatinine requiring any intervention. Our surgical technique has been described previously and involves a fibrin glue bolster secured with parenchymal sutures.

Results

We identified 210 patients who underwent MIPN between May 2006 and October 2016 and met all inclusion criteria. Urine leak occurred in 3/210 (1.4%) patients overall. No patients deemed high risk by RENAL nephrometry score developed urine leak after surgery (0/13). Patients deemed high risk by Renal Pelvis Score had a urine leak rate of 2.0% (3/150), compared to published rate of 23.6%. Additionally, patients at low risk by RENAL score (<7) had leak rate of 1.3% (1/76), while moderate risk patients (7-8) had leak rate of 1.9% (2/103), compared to the published rates of 7.4 and 13.6%, respectively. Only one patient with a tumor size greater than 7cm (n=9) and one with tumor size less than 4cm (n=121) experienced a postoperative urine leak.

Conclusions

Our technique for MIPN shows superior outcomes with respect to urine leak in high-risk patients compared to traditional techniques that include formal collecting system closure. We have successfully applied our approach to pure lap, hand-assisted, and robot-assisted laparoscopic procedures. These results challenge accepted dogma that formal collecting system closure is necessary for the prevention of urine leak formation. Omitting this step decreases the complexity of the closure, shortens warm ischemia time, and may actually reduce the risk of urine leak.

Funding

None