Factors Predicting Outcomes of Supine Percutaneous Nephrolithotomy: Large Single-Centre Experience.

OBJECTIVE: Percutaneous nephrolithotomy (PCNL) is the treatment of choice for large renal calculi. The prone position has been considered the preferred position to obtain renal access. However, the supine position has recently gained popularity, which confers several potential advantages. The current study analyses the prognostic factors for successful supine PCNL procedures in a larger tertiary centre.

SUBJECTS: Prospective data were collected from all patients undergoing PCNL in the Galdako modified Valdivia position at our institution between February-2007 and September-2020. Surgical outcomes variables collected included: the rate of Endoscopic-combined intra-renal surgery (ECIRS), operative times, surgical effectiveness (no residuals <2 mm stone fragments) and complications.

RESULTS: A total of 592 patients underwent PCNL with a median age of 56 years (IQR: 42-67). The median stone size was 17 mm (IQR: 13-23). Of those, 79% of patients had an effective procedure. Stone size ( p < 0.001), location ( p < 0.001) and Guys-Stone Score (GSS) ( p < 0.001) were associated with effectiveness. A Percutaneous nephrostomy tube was sited at the completion of the procedure in 97.3% of patients and a simultaneous double-J stent in 45.3%. Stent insertion was associated with larger stones ( p < 0.001), the performance of ECIRS ( p < 0.001) and higher GSS ( p < 0.001). The overall complication rate was 21.7%. The main type of complication was an infection in 26.2 of the cases followed by the need for repeated nephrostogram in 12.7%.

CONCLUSIONS: We demonstrate that PCNL in a high-volume centre is safe and efficacious in the Galdalko modified Valdivia position. Patients with smaller stones in the renal pelvis and a low GSS have the highest chance of a successful procedure.