To retrospectively evaluate clinical, tumor, and surgical factors that were potential predictors of postoperative unilateral renal function after laparoscopic and open partial nephrectomy.

Sixty-five patients who had undergone partial nephrectomy and had postoperative renal scintigraphy performed were evaluated on the basis of multiple factors as potential predictors of postoperative renal function in the ipsilateral kidney. These factors include patient age, indication for nephron-sparing surgery, type of procedure (laparoscopic vs open), preoperative and postoperative glomerular filtration rate, tumor depth, radiographic and pathologic tumor size, warm ischemia time, and intraoperative visual assessment of functional renal parenchyma preserved. The correlation of each clinical factor to actual postoperative differential renal function, as determined by technetium-99m-mercaptoacetyltriglycine renal scintigraphy, was calculated.

In univariate regression analysis, the only factors found to be significantly correlated with postoperative unilateral renal function as assessed by renal scintigraphy were intraoperative visually estimated preserved parenchyma volume (P <.001), tumor size (radiologic, P = .017; pathologic, P = .041), and procedure type (P = .021). Tumor depth (P = .050) showed borderline significant relation to postoperative unilateral renal function. Multivariate analysis revealed no factors that were jointly prognostic for postoperative scintigraphic differential renal function.

Intraoperative visually estimated functioning residual renal volume was the most accurate predictor of actual postoperative unilateral renal function. Tumor depth had intermediate prognostic value in estimating postoperative split renal function. During both laparoscopic and open partial nephrectomy, intraoperative visual estimation of preserved renal parenchyma volume should be routinely documented.