To our knowledge, this study represents the first direct comparison of standard Amplatz and modified Amplatz sheaths with suction in PCNL for large renal stones. Our findings demonstrate that the modified Amplatz sheath significantly enhances procedural efficiency and patient outcomes compared to the standard sheath. Specifically, the modified sheath group exhibited a shorter operative time, higher SFR, and fewer postoperative complications, including reduced rates of fever and pain. These improvements can be attributed to the design of the modified sheath, which allows for controlled irrigation, improved visualization, reduced intra-renal pressure, and efficient stone fragment clearance through suction.

Suction-assisted techniques in PCNL have been explored previously, highlighting their potential benefits. In agreement with our findings, Tuoheti et al. [8] evaluated the efficacy of a novel double-sheath negative-pressure PCNL (D-mPCNL) compared to conventional PCNL (C-mPCNL) for large kidney stones. Their findings showed that the D-mPCNL group had a significantly shorter operative time (41.97 ± 8.24 min vs. 52.30 ± 13.72 min, P < 0.001), a higher primary SFR (85.3% vs. 70.3%, P = 0.038), and lower rates of postoperative fever (2.9% vs. 14.1%, P = 0.021).

Interestingly, a meta-analysis by Wang et al. indicated that laparoscopic pyelolithotomy (LPL) and PCNL are both effective and safe for large renal pelvic calculi, with LPL showing higher SFRs and lower incidences of bleeding and postoperative fever compared to PCNL. Their study also noted shorter operative times and hospital stays in the PCNL group, but fewer hemoglobin drops in the LPL group [9]. Eshghi et al. reported the successful implementation of laparoscopy-assisted PCNL for treating pelvic kidney stones, highlighting the potential of laparoscopic techniques in managing complex renal stones [10]. Similarly, Santos et al. demonstrated the effectiveness of videolaparoscopy-guided percutaneous transperitoneal nephrolithotripsy, further supporting the benefits of enhanced visualization and access provided by laparoscopic methods [11].

Recently, in their systematic review, Nizzardo et al. [12] examined suction-assisted nephrostomic sheaths in PCNL. They observed SFRs ranging from 71.3 to 100% and complication rates from 1.5 to 38.9%. They also reported a trend towards better SFRs and lower complication rates in suction techniques. Furthermore, they noted a consistent 19-minute reduction in operative time with suction procedures.

Parallel to our results, Zhu et al. [13] compared the treatment outcomes of suctioning MPCNL and traditional MPCNL for renal staghorn stones. They conducted a matched-pair analysis and found that the suctioning MPCNL group achieved a significantly higher SFR after a single procedure (78.5% vs. 69.1%) and had a significantly shorter operative time (106.2 ± 18.4 vs. 132.1 ± 22.2 min) compared to the traditional MPCNL group. Additionally, the suctioning MPCNL group experienced fewer overall complications (16.8% vs. 27.3%) and a lower incidence of fever.

While suction techniques are not novel, our study introduces a practical and cost-effective modification to the standard Amplatz sheath. This modification integrates a laparoscopic port component, enabling simultaneous suction and controlled irrigation without requiring specialized equipment, making it an accessible advancement for clinical practice.

The use of a 30 Fr sheath and 24 Fr nephrostomy in all cases was chosen to accommodate the large stone burden (> 2 cm), facilitating effective stone fragmentation and clearance. Although miniaturized PCNL approaches have gained popularity for smaller stones, the standard 30 Fr sheath remains the contemporary standard of care for large renal stones due to its ability to handle larger fragments and reduce the need for auxiliary procedures.

The modified Amplatz sheath provides several theoretical advantages that contribute to its efficacy. By enabling precise control of irrigation fluid, it ensures a consistently clear surgical field, which enhances visualization during the procedure. Additionally, the suction mechanism reduces intra-renal pressure, thereby minimizing the risk of complications such as pyelovenous backflow and systemic absorption of irrigation fluid. These features collectively contribute to shorter operative times by improving visibility and facilitating the efficient removal of stone fragments [14, 15].

In practice, the benefits observed in this study align with these theoretical advantages. Patients in the modified sheath group demonstrated significantly higher stone-free rates and a reduced need for auxiliary procedures compared to those in the standard sheath group. Operative times were shorter, and postoperative complications, such as fever and infection, were notably decreased. Furthermore, the use of the modified sheath resulted in shorter hospital stays, with the majority of patients being discharged within two days, highlighting its practical utility in improving patient outcome.

Despite the promising findings, this study has several limitations. Firstly, the study was conducted at a single center with a relatively small sample size. Additionally, the study duration may not have allowed for the long-term assessment of stone recurrence rates and the durability of outcomes. Thus, future multi-center studies with larger sample sizes and standardized protocols may enhance the validity and the reproducibility of the results.