European Journal of Cardiovascular Medicine

Percutaneous nephrolithotomy (PCNL) remains the gold standard treatment for large and complex renal calculi, typically those exceeding 2 cm in diameter. Traditionally, PCNL has been performed in the prone position, which offers direct access to the posterior renal calyces but presents several limitations, including challenges in anaesthetic management, increased operative repositioning time, and potential for cardiopulmonary compromise—especially in high-risk or obese patients [1,2]

The supine approach for PCNL, first described by Valdivia et al. in 1987 [3], has gained popularity in recent years. It offers several theoretical and practical advantages: improved anaesthetic access, simultaneous retrograde ureteroscopy (if required), shorter operative times, reduced cardiovascular stress, and less need for patient repositioning [4]. In parallel, the advent of Mini-PCNL, which utilizes smaller access tracts (typically 16Fr–18Fr), has shown promise in reducing morbidity and postoperative discomfort while maintaining stone clearance efficiency [5].

Despite these benefits, widespread adoption of supine PCNL remains limited, with hesitations often linked to the perceived risk of colonic injury, a learning curve associated with fluoroscopic access, and limited experience in resource-limited settings. However, multiple comparative studies have indicated that the stone-free rate (SFR), complication profile, and hospital stay are at least equivalent—if not superior—in supine compared to prone PCNL [6,7].

Moreover, the combination of spinal anaesthesia with supine PCNL remains an underexplored but promising area. Spinal anaesthesia eliminates risks associated with general anaesthesia, particularly in patients with comorbidities, while also providing excellent analgesia and reduced postoperative recovery time [8].

This study presents our initial experience with supine PCNL and mini-PCNL under spinal anaesthesia, conducted in a government tertiary care centre in Central India. We aim to assess its feasibility, safety, and surgical outcomes, contributing to the growing body of literature that supports the paradigm shift from prone to supine PCNL.

This prospective observational study was conducted at the Department of Urology, Government Medical College and Super Specialty Hospital, Nagpur, between January 2023 and September 2023. The aim was to evaluate the feasibility, safety, and surgical outcomes of supine PCNL and mini-PCNL performed under spinal anaesthesia in patients with renal stone disease.

Inclusion and Exclusion Criteria

Inclusion Criteria:

• Patients aged 13 to 71 years with symptomatic renal calculi larger than 10 mm.
• Stone burden confirmed through X-ray KUB, ultrasound, and CT urography.
• Patients fit for spinal anaesthesia.
• No evidence of active urinary tract infection at time of surgery.

Exclusion Criteria:

• Patients requiring bilateral simultaneous procedures.
• Coagulopathy or contraindications to spinal anaesthesia.
• Pregnant females or those with anatomical abnormalities of the urinary tract.

Preoperative Evaluation

All patients underwent:

• Detailed history and physical examination.
• Imaging with ultrasound, X-ray KUB, and CT urography to assess stone size, location, and anatomy.
• Laboratory tests including renal function tests, coagulation profile, urine culture.
• Anaesthetic evaluation for suitability for spinal anaesthesia.

Demographics recorded included age, gender, BMI, stone laterality, and history of prior interventions (ESWL or open/PCNL surgery).

Surgical Technique

Positioning

Two supine positions were utilized:

• Giusti’s modified supine position: Used in patients requiring simultaneous retrograde intrarenal surgery (RIRS).
• Complete supine position: Applied in patients undergoing PCNL alone.

Patients were placed in a supine position with slight flank elevation. All procedures were performed under spinal anaesthesia.

Access and Tract Dilation

• Fluoroscopy-guided retrograde pyelography (RGP) was used for calyceal identification and access planning.
• Monoplanar fluoroscopic technique was used to puncture the selected calyx.
• Access site distribution:
• Lower calyx: 52% (n=18)
• Middle calyx: 26% (n=9)
• Upper calyx: 11% (n=4)
• Multiple tracts: 11% (n=4)

Tract dilation and instrument size:

• Standard PCNL (24Fr Amplatz tract): 27 cases
• Mini-PCNL (18Fr tract): 8 cases

(All mini-PCNL cases were planned to be tubeless)

Stone Fragmentation

Stones were fragmented using a Swiss pneumatic lithoclast, and fragments were removed with forceps or irrigation.

Exit Strategy

Three different approaches were used based on intraoperative findings:

• Total Tubeless (n=16): Ureteric catheter left for 12–24 hours only.
• Tubeless with DJ stent (n=14): Used especially in all mini-PCNL cases.
• Nephrostomy plus DJ stent (n=5): Used in cases with bleeding or residual fragments.

Outcome Parameters

The following perioperative variables were assessed:

• Operative time (skin puncture to completion of procedure)
• Tract size and number
• Renal access site
• Exit strategy
• Complications, categorized by Clavien-Dindo classification
• Hospital stay
• Stone-free rate (SFR), assessed via imaging at 6 weeks post-procedure
• Readmission rate

PHOTOS

GIUSTI’S SUPINE POSITION                                    COMPLETE SUPINE POSITION

When we need retrograde access                        When we plan for only supine PCNL

                           Or planning for dual procedure

Nephroscopy , Lithotripsy and fragment retrieval

Exit strategy depending on procedure

A total of 35 patients underwent supine PCNL or mini-PCNL under spinal anaesthesia during the study period from January 2023 to September 2023. The baseline characteristics of the study population are summarized below.

The mean age of the patients was 43.5 years, ranging from 13 to 71 years. The majority of patients were male (60%), with a mean BMI of 26.6 kg/m² (range: 19–32.5 kg/m²), indicating that a significant proportion of the cohort were overweight or mildly obese. A left-sided renal stone was more commonly encountered than right-sided.

Three patients had a history of prior renal stone interventions: one had undergone extracorporeal shock wave lithotripsy (ESWL), while two others had undergone open or prior PCNL surgery. The preoperative evaluation included imaging via ultrasound, X-ray KUB, and CT urography, which confirmed the stone burden and anatomical suitability for supine access.

The demographic and baseline clinical data are detailed in the table below:

Table 1: Patient Demographics and Baseline Characteristics

 Laterality and Stone Characteristics

Among the 35 patients, the majority presented with left-sided renal stones (n = 22, 62.9%), while the remaining had right-sided stones (n = 13, 37.1%). Stone location within the kidney was most commonly in the lower calyx, accessed in 18 cases (51.4%). Other puncture sites included the middle calyx (n = 9) and upper calyx (n = 4). In 4 patients (11.4%), multiple calyceal accesses were required due to large stone burden or complex anatomy.

Stone fragmentation was performed using a pneumatic lithoclast in all patients, and access was achieved through either standard or mini tracts depending on stone size and location. A small number of patients (n = 3) underwent combined ureteroscopic stone removal (URSL) along with PCNL in the same session.

Table 2: Stone Laterality and Calyceal Access Site

 Operative Details

All procedures were conducted in the supine position under spinal anaesthesia, following retrograde pyelography (RGP) and monoplanar fluoroscopic guidance for calyceal puncture. The selection of tract size and access site was individualized based on stone burden, anatomical considerations, and surgeon preference.

A standard tract size of 24 French (Fr) was used in 27 patients (77.1%), whereas a mini-PCNL tract (18Fr) was chosen in 8 patients (22.9%). Mini-PCNL was typically reserved for smaller stones and aimed at achieving tubeless discharge with minimal morbidity. All tracts were dilated using Amplatz dilators.

The lower calyx was the most frequently accessed site, accounting for 51.4% (n = 18) of cases. The middle calyx was punctured in 9 patients (25.7%), and the upper calyx in 4 patients (11.4%). In 4 patients (11.4%), multiple tracts were required to achieve complete stone clearance, primarily in cases of complex or staghorn calculi.

Additionally, combined endoscopic procedures were performed in 3 patients (8.6%), where ureteroscopic lithotripsy (URSL) was carried out along with PCNL in the same setting due to concomitant ureteral stones.

A summary of tract types and access distribution is provided in Table 3, with visual representation in Figure 1 and Figure 2.

Table 3: Operative Characteristics

Figure1: Tract Size Distribution

Figure1: Bar chart showing the distribution of tract sizes (Standard vs Mini-PCNL) used in the study.

Figure2: Calyceal Access Site Distribution

Figure2: Pie chart illustrating the proportion of calyceal access sites (Lower, Middle, Upper, and Multiple Tracts) among patients undergoing PCNL.

 Exit Strategy

At the conclusion of each procedure, the postoperative drainage strategy was tailored based on intraoperative findings such as bleeding, residual fragments, and overall tract trauma. A total of three distinct exit strategies were employed.

A total tubeless approach, where neither a nephrostomy tube nor a DJ stent was placed and only a ureteric catheter was used temporarily (12–24 hours), was adopted in 16 patients (45.7%), all of whom underwent standard PCNL and had favourable intraoperative profiles.

In 14 patients (40.0%), a DJ stent was placed without nephrostomy tube — a “tubeless” approach commonly favoured in mini-PCNL cases. Notably, all mini-PCNL procedures (n = 8) were managed using this method.

The remaining 5 patients (14.3%) received both a nephrostomy tube and a DJ stent, largely due to significant bleeding, suspected residual fragments, or complex anatomy.

These choices are summarized in Table 5. A significant association was found between tract type and exit strategy (p = 0.0004, Chi-square test), confirming that mini-PCNL was exclusively associated with tubeless management using DJ stents.

Table 4: Distribution of Exit Strategy by Tract Type

 Operative Outcomes

The mean operative time across all procedures was 68.8 minutes, with a range of 45 to 116 minutes. When stratified by technique, the mean operative duration was 24.84 minutes for standard PCNL and 18.27 minutes for mini-PCNL.

Postoperative imaging at 6 weeks demonstrated a stone-free rate (SFR) of 94.3% (33/35 patients). The two patients with residual stones underwent adjuvant extracorporeal shock wave lithotripsy (ESWL) and subsequently achieved clearance.

The mean hospital stay was 4.8 days, ranging from 3 to 6 days, with no significant difference observed between mini and standard PCNL groups.

Table 5: Operative Outcomes

The overall stone-free rate (SFR) was 94.3%. There was no statistically significant difference in SFR when comparing standard PCNL vs mini-PCNL (p = 1.0, Fisher’s Exact test), nor when comparing right- vs left-sided stones (p = 1.0). These findings suggest that both tract types and laterality had no measurable impact on short-term stone clearance in this cohort.

Complications

Postoperative complications were recorded in accordance with the Clavien-Dindo classification system. Overall, 10 patients (28.6%) experienced complications, the majority of which were minor (Grade I or II) and managed conservatively.

The most frequent complication was fever or infection, occurring in 6 patients (17.1%), of whom five had perinephric collections managed with intravenous antibiotics. One patient (2.9%) required a blood transfusion for haemoglobin drop, classified as Clavien Grade II.

Three patients (8.6%) required readmission: two had undergone total tubeless PCNL and presented with persistent fever and perinephric collection, managed with DJ stenting and bladder catheterization under local anaesthesia (Grade IIIa). The third had undergone nephrostomy drainage and was managed conservatively (Grade II).

Importantly, there were no cases of colonic or pleural injury, and no mortality was reported.

A detailed breakdown of complications and their severity is presented in Table 6.

Table 6: Postoperative Complications and Clavien-Dindo Classification

 Subgroup Comparisons

To explore whether patient or procedural characteristics influenced surgical outcomes or complication profiles, several subgroup analyses were conducted.

Mini-PCNL vs Standard PCNL

When comparing Mini-PCNL (n=8) to Standard PCNL (n=27), there were no significant differences in stone-free rates (p = 1.0, Fisher’s Exact test) or complication rates (p = 0.39, Fisher’s Exact test). However, Mini-PCNL procedures had shorter operative times (mean: 18.3 min vs. 24.8 min), and all were managed with tubeless DJ stent placement, showing a strong association between tract type and exit strategy (p = 0.0004, Chi-square test).

Exit Strategy and Postoperative Complications

Complication rates differed significantly based on the exit strategy used (p = 0.014, Chi-square test). The nephrostomy + DJ stent group had the highest complication burden (80%), while the total tubeless group had the lowest (12.5%).

Access Site and Outcomes

No significant associations were found between access site (lower vs other calyces) and either stone-free rate or complication rate (p > 0.4 for both, Fisher’s Exact test), suggesting that lower calyx access — although preferred — did not confer a measurable safety or efficacy advantage in this cohort.

Percutaneous nephrolithotomy (PCNL) continues to be the cornerstone for managing large and complex renal calculi, and innovations in patient positioning, tract miniaturization, and anaesthesia have redefined its application in contemporary urology [9]. This prospective observational study adds to the growing body of evidence supporting the feasibility and safety of supine PCNL and mini-PCNL under spinal anaesthesia, while also providing a focused analysis of operative efficiency, complication patterns, and predictive procedural variables.

Supine Position: Ergonomics and Safety

Supine PCNL was originally introduced to improve anaesthetic safety and procedural ergonomics [10]. In our study, we observed that left-sided renal stones were more common, and lower calyx access was the most frequently employed route. This approach aligns with findings from Basulto-Martínez et al., who reported enhanced access and reduced patient discomfort in the supine position [13].

Our data showed that supine positioning allowed smooth intraoperative transitions and avoided the need for repositioning, a benefit also emphasized in earlier literature [11]. Despite concerns expressed by Lashay et al. regarding the technical challenges and limited evidence for supine PCNL in complex or obese patients [10], our study, like that of Gupta et al., found no significant difference in stone-free rate or complications based on laterality or access site, suggesting that supine PCNL is viable even in diverse clinical scenarios [12].

Tract Size: Mini vs Standard

Miniaturization has emerged as a key innovation in PCNL, aiming to reduce morbidity without compromising stone clearance. In our cohort, mini-PCNL (18Fr) was associated with shorter operative times and was exclusively performed using DJ stent drainage (tubeless), confirming its utility in select, smaller stone burdens. The findings echo those by Ganpule et al., who highlighted that technological advances allow smaller tracts to achieve comparable outcomes while reducing bleeding and pain [9].

Importantly, stone-free rates were comparable between standard and mini-PCNL (p = 1.0). This supports the conclusion from a systematic review by Mak et al., which found no consistent superiority in outcome when comparing different positions or tract sizes in PCNL [11].

Exit Strategy as a Predictor of Complications

Among all procedural variables analyzed, exit strategy had the strongest association with postoperative complications (p = 0.014). Patients receiving nephrostomy tubes had the highest complication rates, while those undergoing total tubeless PCNL had the fewest. This trend aligns with the prospective study by Gupta et al., who observed that totally tubeless supine PCNL yielded good outcomes and low morbidity, especially when combined with spinal anaesthesia [12].

In our study, all mini-PCNL patients were managed with DJ stents alone, reinforcing the growing preference for tubeless strategies in minimally invasive access tracts. These results highlight the need to tailor exit strategies to intraoperative findings rather than adopting a one-size-fits-all approach.

Anaesthesia Modality and Safety

The entire series was performed under spinal anaesthesia, with no major anaesthesia-related complications. This reflects findings from Gupta et al., who also demonstrated spinal anaesthesia as a safe and effective modality in supine PCNL [12]. Given the increasing need for safe anaesthesia in high-risk patients, spinal anaesthesia may serve as a valuable alternative to general anaesthesia in well-selected cases.

Clinical Implications

The key takeaway from our study is that tract type and access site, although clinically relevant, were not independently associated with outcomes, while exit strategy selection emerged as a modifiable factor that significantly influenced complication rates. This underscores the importance of individualized drainage planning and suggests that minimally invasive techniques can safely reduce postoperative morbidity, provided patients are appropriately selected.

Limitations

While this prospective observational study offers valuable insight into the feasibility and outcomes of supine and mini-PCNL under spinal anaesthesia, certain limitations must be acknowledged:

1. Single-centre design: The findings may not be generalizable to all surgical settings, particularly those with different case volumes, surgeon experience, or access to resources.
2. Small sample size (n = 35): While the results are consistent with existing literature, the sample may not be powered to detect subtle differences, particularly in subgroup analyses.
3. Short-term follow-up: Stone-free rates were evaluated at 6 weeks. Long-term outcomes such as stone recurrence or delayed complications were not assessed.
4. Selection bias: Mini-PCNL was selectively offered to patients with smaller stone burdens, which may limit direct comparability with standard PCNL.
5. Lack of randomization: As with all observational studies, the absence of random allocation introduces potential bias in procedural decision-making (e.g., choice of exit strategy).

Despite these limitations, the study provides practical, real-world data supporting the use of supine and mini-PCNL under spinal anaesthesia in well-selected patients.

Supine PCNL and mini-PCNL performed under spinal anaesthesia are safe, effective, and feasible treatment modalities for renal calculi. In this study, both techniques achieved high stone-free rates with minimal complications. Notably, while tract size and access site were not significantly associated with outcomes, the choice of exit strategy emerged as a key predictor of postoperative complications.

These findings support the broader use of tubeless and totally tubeless techniques, particularly in cases where mini-PCNL is employed. With careful patient selection and appropriate intraoperative decision-making, supine PCNL under spinal anaesthesia can offer a highly efficient and patient-friendly alternative to traditional prone approaches.

Future multicentre, randomized trials with larger sample sizes and longer follow-up are warranted to validate these observations and refine guidelines for optimal technique selection in PCN.

1. Fernström I, Johansson B. Percutaneous pyelolithotomy. A new extraction technique. Scand J Urol Nephrol. 1976;10(3):257–259. doi:10.3109/00365597609181163
2. Kumar S, Yadav S, Srivastava A, et al. Safety and efficacy of PCNL in high-risk patients: A prospective study. Urol Ann. 2015;7(1):31–35. doi:10.4103/0974-7796.148604
3. Valdivia-Uria JG, Valle-Gerhold J, Lopez-Ledo MJ, et al. Technique and complications of percutaneous nephroscopy: Experience with 557 patients in the supine position. J Urol. 1998;160(6 Pt 1):1975–1978. doi:10.1016/S0022-5347(01)62232-1
4. Falahatkar S, Mokhtari G, Teimoori M. An Update on Supine PCNL: Advantages, Indications, and Limitations. World J Urol. 2014;32(3):713–721. doi:10.1007/s00345-014-1285-3
5. Jackman SV, Docimo SG, Cadeddu JA, et al. The “Mini-Perc” technique: A less invasive alternative to percutaneous nephrolithotomy. World J Urol. 1998;16(6):371–374. doi:10.1007/s003450050091
6. Liu L, Zheng S, Xu Y, et al. Supine versus prone position in percutaneous nephrolithotomy for kidney calculi: A meta-analysis. BMC Urol. 2020;20:38. doi:10.1186/s12894-020-00621-6
7. Scoffone CM, Cracco CM, Cossu M, et al. Endoscopic combined intrarenal surgery in Galdakao-modified supine Valdivia position: A new standard for percutaneous nephrolithotomy? Eur Urol. 2008;54(6):1393–1403. doi:10.1016/j.eururo.2008.07.063
8. Adanur S, Ozkaya F. The efficacy and safety of PCNL under spinal versus general anesthesia: A prospective randomized study. Urolithiasis. 2013;41(4):265–270. doi:10.1007/s00240-013-0568-5
9. Ganpule AP, Vijayakumar M, Malpani A, Desai MR. Percutaneous nephrolithotomy (PCNL): A critical review. Int J Surg. 2016;36(Pt D):660-664. doi:10.1016/j.ijsu.2016.11.028.
10. Lashay A, Amini E, Ahanian A, et al. Supine percutaneous nephrolithotomy: con. Urol J. 2011;8(4):265-268.
11. Mak DK, Smith Y, Buchholz N, El-Husseiny T. What is better in percutaneous nephrolithotomy - Prone or supine? A systematic review. Arab J Urol. 2016;14(2):101-107. doi:10.1016/j.aju.2016.01.005.
12. Gupta S, Maurya AK, Pal DK. Observational prospective study for surgical outcome and anesthetic feasibility of tubeless and totally tubeless supine PCNL: A single centre initial experience. Turk J Urol. 2018;45(2):146-149. doi:10.5152/tud.2018.97345.
13. Basulto-Martínez M, Proietti S, Yeow Y, et al. Technique for supine percutaneous nephrolithotomy. Urology Video Journal. 2020;7.