AUA 2019: Feasibility of Omitting Outer (Cortical) Renorrhaphy During Robotic Partial Nephrectomy - A Multi-Institutional Analysis

Chicago, IL ( Renorrhaphy during partial nephrectomy is usually performed in two phases. In the first or inner phase, the base of the area where the tumor was excised from the kidney is oversewn to establish hemostasis. Peripheral defects in the collecting system may also be closed during this time. In the second (the “outer” or “cortical”) phase, the capsule of the kidney is approximated over the defect.   This is often assisted by the placement of a bolster (often fat or hemostatic agent) which fills the empty space previously occupied by the tumor.

Some have recently proposed omitting this closure to decrease ischemic injury to healthy nephrons that would otherwise be incorporated into the closure, decrease ischemia time (if the closure is performed while on clamp), and decrease operative time. The effect on postoperative bleeding and pseudoaneurysm formation is unknown. The outer closure is performed largely because intuition tells the surgeon that it assist in hemostasis, but as one audience member (Dr. Matthew Winter, University of Southern California) pointed out during this session, it may also alter the morphology of the underlying tissue, loosening or otherwise altering the effectiveness of the deeper layer of closure.

In this study, presented by Dr. Sohrab Arora, the Vattikuti Collective Quality Initiative Database, which includes data from 41 surgeons at 14 centers in 9 countries, was queried for patients undergoing partial nephrectomy between 2006 and 2018. 1360 total patients were identified, 120 of which did not undergo a cortical renorrhaphy. Inverse probability of treatment weighting was used to correct for a number of clinical factors (including most importantly tumor size, polar location, and nephrometry score) and Firth correction was applied to reduce bias introduced by practice variation between centers.

No difference was found between cortical renorrhaphy across any of the relevant outcomes, including change in GFR, operative time, ischemia time, estimated blood loss, length of stay, postoperative grade 3 or greater complications, or need for angioembolization within 1 year of surgery, although numerically these last two did favor cortical renorrhaphy (1.0 vs 2.8% p = 0.2 and 0.7 vs 1.4% p=0.4).

Given that cortical renorrhaphy was only excluded in 8.8% of patients and no claims are made to any particular surgeon in the database omitting this as a matter of standard practice, one can only suppose that this is a very highly selected group of patients, and the differences between this group and the overall cohort of patients undergoing partial nephrectomy are unlikely to be fully controlled for with even sophisticated statistical techniques. Thus while this data likely allows us to conclude that there exists some group of patients for whom cortical renorrhaphy can be safely omitted with little to no effect on clinical outcomes, and surgeons in this database seem to be able to select those patients reasonably well, there is little guidance here for how a surgeon looking to try this technique should go about selecting those patients in her own practice.

Presented by: Sohrab Arora, MD, Senior Fellow - Robotic Surgery, Henry Ford Health System, Detroit, Michigan

Written by: Marshall Strother, MD, Chief Resident, Division of Urology, University of Pennsylvania, Philadelphia PA at American Urological Association's 2019 Annual Meeting (AUA 2019), May 3 – 6, 2019 in Chicago, Illinois