Percutaneous nephrolithotomy (PCNL) has been performed for decades and has gone through many changes and refinements, and there are concerns regarding its long learning curve and the potential risk of severe complications.¹ Traditionally, surgical outcomes after kidney stone surgery have been focused on “stone-free” status as a way to define success. However, absolute stone-free status is difficult to achieve despite our best efforts. For the treatment of large and complex stones there are relevant techniques able to improve the outcomes.

Evolution in the endoscopic instrumentation and in the surgical skills improved the success rates and the perioperative morbidity. The first combined renal surgery description, by Lehman and Bagley, was in 1988 and performed in prone position (fig. 1).² More recently in 2008, Scoffone et al created the term endoscopic combined intrarenal surgery (ECIRS) for the approach in Galdakao-modified supine Valdivia position, gaining enthusiasts worldwide with the benefit of performing the procedure without changing the patient positioning (fig. 2).³ In fact, the endoscopic combined technique is a way to approach simultaneously the largest number of renal calyxes anterogradely and retrogradely that allows optimization of the PCNL efficacy and safety.⁴

Figure 1. Reverse lithotomy position (original picture). Patient placed in prone position with adequate padding, both legs supported, with access available both to urethra and nephrostomy site.²

 

Figure 2. ECIRS performed in supine position.

As in traditional PCNL, positioning is always a debate. The prone position is traditionally used, and variations of the supine technique have been proposed and assessed over time. The major advantages of supine PCNL compared with standard prone PCNL are the optimal cardiovascular anesthetic management and shorter operation time due to repositioning. Some cited advantages in the prone position are a larger surface area for the access, a wider space for manipulating the nephroscope and the opportunity for bilateral simultaneous PCNL.⁵

Figure 3. Intraoperative retrograde view in a combined approach.

Recently, we performed a randomized prospective trial comparing position in the treatment of complex stones and concluded, as in previous systematic reviews and studies with noncomplex cases, that positioning during PCNL for complex kidney stones did not affect the success rates. Consequently, both positions may be suitable. However, we could observe that the supine group had a significantly lower rate of major complications (Clavien score >2),⁶ which was also reported on the meta-analysis, especially regarding infectious complications.⁷ Our hypothesis is that the intrarenal pressure during surgery is higher in prone than in supine, which would cause a pyelovenous reflux leading to higher risk of fever and sepsis. We have tested this hypothesis in a randomized study not yet published and could verify that the mean intrarenal pressure is significantly higher in prone than in supine during PCNL for simple cases.

The criticism of combined surgery in prone position is the difficulty and time in positioning the patient, but these statements probably rely on the repositioning of the patient in traditional prone position and the ureteral access, which could be optimized in the prone split-leg position.^8,9 There are rarely issues regarding repositioning, such as tracheal tube dislodgment or clinical instability, showing that both positions are safe options when done properly. Another point is the unusual position of the flexible ureteroscope during the retrograde nephroscopy, easily correctable with surgeon’s experience.

High-quality prospective studies comparing ECIRS to traditional PCNL are lacking. Observational studies show its real benefits, such as the puncture and dilation visualization, lower bleeding and transfusion rates, lower number of percutaneous accesses, simultaneous treatment of ureteral and renal stones, and better access to all the collecting system retrogradely (fig. 3).⁴ The major limitations could be the higher costs, but the opportunity of treating complex cases and rendering the patient stone-free in a single session is very attractive.

However, there are no randomized studies comparing prone vs supine ECIRS. During ECIRS, the kidney is usually drained by a ureteral access sheath. We believe that intrarenal pressure may remain low in prone as in supine, eventually reducing infectious complications. Prospective studies with a significant number of patients may reach definitive conclusions about the ECIRS safety profile. For the moment, both positions seem equally effective and suitable for the combined approach, not impacting success. All surgeons should be trained in both techniques and choose which is optimal for their patients. But there is a tendency that when a determined group performs PCNL in both positions, after some time most surgeries will be performed in supine, showing that–if the results are the same–surgeons tend to do what is easier and faster.¹⁰