Urolithiasis is a common and increasingly prevalent disorder of the urinary tract that affects millions of individuals worldwide and represents a significant source of morbidity within urological practice.1The lifetime prevalence of urinary stone disease is estimated to range between 10% and 15%, with recurrence rates approaching 50% within five years after the initial episode.2 Renal calculi, commonly referred to as kidney stones, can lead to severe flank pain, hematuria, urinary tract obstruction, recurrent infections, hydronephrosis, and, in severe cases, progressive renal impairment if left untreated.3 Various factors contribute to stone formation, including metabolic abnormalities, dehydration, dietary habits, obesity, genetic predisposition, and environmental influences.4 The burden of urolithiasis is particularly high in developing countries due to climatic conditions, poor hydration practices, and limited awareness regarding preventive strategies.5

The management of renal calculi has evolved significantly over the past few decades, transitioning from open surgical procedures to minimally invasive techniques aimed at reducing patient morbidity and improving recovery.6 Among the available treatment modalities, percutaneous nephrolithotomy (PCNL) has become the gold standard for managing large renal stones, particularly those greater than 2 cm in diameter, staghorn calculi, multiple stones, and stones resistant to extracorporeal shock wave lithotripsy (ESWL).7 Since its introduction by Ferns Trom and Johansson in 1976, PCNL has revolutionized the treatment of complex renal calculi by providing high stone-free rates with reduced invasiveness compared to open surgery.8

Traditionally, PCNL is performed with the patient in the prone position, a technique that has been widely adopted due to its favorable anatomical exposure, broad access to the posterior renal calyces, and perceived ease of percutaneous puncture.9 The prone position offers surgeons a large surface area for renal access and minimizes the risk of visceral injury due to posterior approach anatomy.10 However, despite these advantages, prone PCNL has several limitations and challenges. Positioning the patient prone requires initial placement in the lithotomy position for ureteric catheterization followed by repositioning, which increases operative time and may contribute to patient discomfort and logistical difficulties in the operating room. Furthermore, the prone position can pose anesthetic concerns such as limited airway accessibility, impaired cardiopulmonary function, increased intrathoracic pressure, and difficulty in ventilating obese or medically compromised patients.11

To overcome these limitations, the supine position for PCNL was introduced by Valdivia and colleagues in 1987 as an alternative approach.12 Supine PCNL has gained popularity in recent years due to several potential advantages, including easier patient positioning, improved airway control for anesthesiologists, reduced cardiovascular and respiratory compromise, elimination of patient repositioning during surgery, and the possibility of simultaneous retrograde intrarenal surgery13 if needed. In addition, the supine position may provide better ergonomic comfort for surgeons and facilitate spontaneous drainage of stone fragments through gravity-assisted evacuation.

Despite the increasing adoption of supine PCNL, controversy remains regarding whether it offers comparable efficacy and safety to the traditional prone approach. Some studies suggest that supine PCNL is associated with shorter operative time, reduced fluoroscopy exposure, shorter hospital stay, and decreased postoperative complications, whereas others argue that prone PCNL provides superior renal access and technical familiarity, particularly for complex stones.14 The choice of patient positioning during PCNL remains largely dependent on surgeon preference, institutional protocol, and patient-specific clinical considerations.

Several comparative studies and meta-analyses have attempted to evaluate the relative benefits and limitations of supine and prone PCNL.15 While many have demonstrated similar stone-free rates between the two approaches, variations in operative efficiency, radiation exposure, complication profiles, and postoperative recovery continue to be debated. Given the importance of optimizing surgical outcomes and minimizing complications, further evidence is needed to guide clinicians in selecting the most appropriate patient position for PCNL.

The present study was therefore conducted to compare supine and prone PCNL in terms of operative efficiency, fluoroscopy duration, stone clearance rates, hospital stay, and perioperative complications in patients undergoing renal stone surgery at a single tertiary care center. By evaluating and comparing the outcomes of these two commonly used techniques, this study aims to contribute to the growing body of evidence regarding the optimal positioning strategy for PCNL and provide practical insights for improving patient care in modern urological practice

Study Design: This prospective comparative study was conducted at Pakistan Kidney Centre over a period of 2 years.

Study Population:A total of 196 patients diagnosed with renal calculi requiring PCNL were enrolled.

Inclusion Criteria

• Patients aged 18–70 years
• Renal stones >2 cm
• Complex/multiple renal calculi
• Failed ESWL cases
• Patients fit for general anesthesia

Exclusion Criteria

• Active urinary tract infection
• Coagulopathy
• Pregnancy
• Severe skeletal deformities
• Congenital renal anomalies

Grouping Patients were equally divided into

• Group A: Supine PCNL (n=98)
• Group B: Prone PCNL (n=98)

Surgical Procedure

All procedures were performed under general anesthesia by experienced consultant urologists.

Supine PCNL Technique

Patients were positioned in modified Valdivia supine position with mild flank elevation. Percutaneous renal access was obtained under fluoroscopic guidance.

Prone PCNL Technique

Patients were initially placed in lithotomy position for ureteric catheterization and then repositioned prone for renal puncture and stone removal.

Data Collection

Variables recorded included:

• Age and gender
• Stone size
• Operative time
• Fluoroscopy time
• Stone-free rate
• Length of hospital stay
• Intra/postoperative complications

Statistical Analysis

Data were analyzed using SPSS version 25. Continuous variables were expressed as mean ± SD. Independent t-test and chi-square test were applied. A p-value <0.05 was considered statistically significant.

Demographic Characteristics

No statistically significant difference was observed between both groups regarding baseline demographic and stone characteristics.

Operative Outcomes

Perioperative Complications

Supine PCNL demonstrated fewer postoperative complications compared to prone P

PCNL remains the preferred intervention for large renal stones. While prone PCNL has long been considered standard, supine PCNL has gained popularity due to its ergonomic and anesthetic advantages.

In the present study, operative time was significantly shorter in the supine group, likely due to avoidance of patient repositioning and easier instrument maneuverability. Similar findings were reported by Valdivia et al. and Falahatkar et al.

Fluoroscopy time was significantly reduced in the supine group, suggesting better visualization and more direct tract access. Reduced fluoroscopy exposure minimizes radiation hazards to both patient and surgical staff.

Stone-free rates were comparable between both groups, indicating that supine PCNL is equally effective for stone clearance. This aligns with previous meta-analyses showing no significant difference in stone-free success.

Hospital stay was shorter in supine patients, possibly due to faster postoperative recovery and fewer complications. Additionally, supine PCNL showed fewer postoperative complications, supporting its safety profile.

The prone position, although providing wider puncture access, may increase cardiopulmonary strain, anesthetic difficulty, and operative complexity, particularly in obese or cardiopulmonary compromised patients.

Limitations of Study

• Single-centre design
• Limited sample size
• Lack of long-term follow-up
• No subgroup analysis by stone complexity

Future multicentre randomized trials are recommended

Supine PCNL is a safe, effective, and feasible alternative to prone PCNL. It offers significant advantages including shorter operative time, decreased fluoroscopy exposure, reduced hospital stay, and lower complication rates while maintaining similar stone-free outcomes. Surgeons should consider supine PCNL as a valuable option, especially in selected patients with anesthetic or positioning concerns

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