To evaluate preoperative and intraoperative predictors of conversion to radical nephrectomy (RN) in a cohort of patients undergoing a planned partial nephrectomy (PN) for renal cell carcinoma (RCC).

A single-center, retrospective review was conducted using our PN database that includes patients who were scheduled to undergo PN (regardless of the approach) but were converted to RN between August 1990 and December 2016. Reasons for conversion were collected from the operative report. Patient demographics and perioperative variables were compared with the successful PN group. Univariate and multivariate logistic regression analyses were conducted to assess predictors of conversion.

A total of 1857 patients were scheduled to undergo PN. Of these patients, 90 (5%) were converted to RN. The multivariate model showed that larger tumor size (odds ratio [OR] = 1.20, P = .040), higher RENAL nephrometry score (OR = 1.41, P = .001), hilar tumor or renal sinus invasion (OR = 2.80, P = .004), laparoscopic PN (OR = 7.34, P <.001), intraoperative bleeding (OR = 19.62, P <.001), positive surgical margin (OR = 31.85, P <.001), and advanced pathologic tumor-stage (T3 or T4) (OR = 7.29, P <.001) were associated with increased odds of intraoperative conversion to RN.

The rate of conversion to RN was low in patients who were scheduled to undergo PN in this series. Larger tumor size with increasing complexity, hilar tumor location or renal sinus invasion, locally advanced tumors, laparoscopic PN but not robotic PN, bleeding complication, and positive surgical margin were associated with intraoperative conversion from scheduled PN to RN.