Renal stone disease (urolithiasis) is one of the most common disorders affecting the urinary tract and represents a significant cause of morbidity worldwide.1 The prevalence of kidney stones has increased over the past few decades due to changes in dietary habits, obesity, sedentary lifestyles, metabolic disorders, and environmental factors.2 The lifetime risk of developing renal calculi is estimated to be approximately 10–15%, with recurrence rates approaching 50% within five years if preventive measures are not implemented.3 Patients commonly present with flank pain, hematuria, urinary tract infections, or obstruction of the urinary system, leading to impaired renal function and reduced quality of life.4 Consequently, effective management strategies that ensure complete stone clearance while minimizing treatment-related complications remain a major objective in contemporary urological practice.5

Treatment of renal calculi depends on stone size, location, composition, anatomical considerations, and patient-related factors.6 Small renal stones are generally managed conservatively or with extracorporeal shock wave lithotripsy (ESWL) and flexible ureteroscopy, whereas larger stones (>20 mm), staghorn calculi, or complex renal stones usually require percutaneous nephrolithotomy (PCNL).7 Since its introduction in the late 1970s, PCNL has become the gold standard surgical procedure for managing large renal stones due to its high stone-free rates and ability to treat complex stone burdens in a single session.8 Standard PCNL employs a nephrostomy tract ranging from 24 to 30 French, allowing efficient fragmentation and extraction of stone fragments while maintaining excellent visualization.9

Despite its high efficacy, standard PCNL is associated with several perioperative complications, primarily related to the relatively large renal access tract.10 Renal parenchymal trauma may result in significant bleeding requiring blood transfusion, postoperative pain, prolonged hospitalization, urinary leakage, infection, fever, and, in rare instances, injury to adjacent organs.11 Bleeding remains one of the most important complications because tract size directly influences the extent of renal tissue damage and vascular injury.12 As surgical technology has advanced, considerable efforts have focused on reducing access tract size without compromising stone clearance.

Miniaturized percutaneous nephrolithotomy (mini-PCNL) was developed as a refinement of conventional PCNL with the aim of decreasing surgical morbidity.13 Mini-PCNL utilizes smaller access sheaths, typically ranging from 14 to 20 French, thereby reducing renal parenchymal injury during tract dilation.14 Advances in endoscopic optics, laser lithotripsy, and suction-assisted instruments have enabled mini-PCNL to achieve effective stone fragmentation and evacuation despite the smaller tract diameter. The procedure has gained increasing popularity for managing small-to-moderately sized renal stones and selected complex calculi.

Several clinical studies have demonstrated that mini-PCNL may reduce intraoperative blood loss, postoperative pain, analgesic requirements, and duration of hospital stay compared with standard PCNL.15 The smaller nephrostomy tract is associated with less tissue trauma, resulting in lower postoperative discomfort and faster recovery.16 Furthermore, improvements in endoscopic equipment have allowed surgeons to maintain high stone-free rates comparable to those achieved with conventional PCNL. However, concerns remain regarding potentially longer operative times due to slower fragment extraction and the technical challenges associated with smaller working channels. Therefore, the balance between procedural safety and treatment efficacy continues to be an area of active investigation.

One of the primary indicators of surgical safety during PCNL is perioperative blood loss, commonly assessed by postoperative hemoglobin decline and transfusion requirements.17 Similarly, postoperative pain significantly influences patient satisfaction, mobilization, analgesic consumption, and recovery. Duration of hospitalization reflects both surgical morbidity and healthcare resource utilization, making it an important outcome measure. Equally important is the stone-free rate, which remains the principal indicator of procedural success because residual stone fragments increase the risk of recurrence, infection, and repeat intervention.18 Comprehensive assessment of postoperative complications using standardized systems such as the Clavien–Dindo classification further facilitates objective comparison between different surgical techniques.

Although numerous international studies have compared mini-PCNL and standard PCNL, variations in patient demographics, stone characteristics, surgical expertise, and healthcare settings limit the generalizability of their findings. Data from Pakistan remain relatively limited, particularly regarding perioperative outcomes in routine clinical practice. Considering the increasing burden of urolithiasis in the region and the growing adoption of minimally invasive endourological techniques, local evidence is necessary to guide surgical decision-making and optimize patient outcomes.

The present comparative study was therefore conducted at Pakistan Kidney Centre to evaluate and compare mini-PCNL and standard PCNL in patients undergoing surgical management of renal calculi. The study specifically aimed to assess differences in hemoglobin drop, postoperative pain measured using the Visual Analogue Scale (VAS), duration of hospital stay, stone-free rate, and postoperative complications classified according to the Clavien–Dindo grading system. By comparing these clinically relevant outcomes, this study seeks to determine whether mini-PCNL offers superior perioperative safety while maintaining treatment efficacy comparable to standard PCNL in the management of renal stone disease.

A comparative observational study was conducted at Pakistan Kidney Centre from March 2024 to March 2026 involving 195 patients who underwent percutaneous nephrolithotomy (PCNL) for renal calculi. Patients were divided into two groups based on the surgical technique employed: standard PCNL (n = 110) and mini-PCNL (n = 85). Adult patients with renal stones ≥20 mm or complex renal calculi requiring PCNL were included, while those with uncorrected coagulopathy, active urinary tract infection, pregnancy, congenital renal anomalies, previous open renal surgery, or incomplete clinical data were excluded. All patients underwent routine preoperative clinical, laboratory, and radiological evaluation, including non-contrast CT of the kidneys, ureters, and bladder. Surgical procedures were performed under general anesthesia by experienced urologists using standard operative techniques appropriate for each group. Data collected included demographic characteristics, stone size, operative time, hemoglobin drop, postoperative pain assessed using the Visual Analogue Scale (VAS), duration of hospital stay, stone-free status determined by postoperative imaging, and complications classified according to the Clavien–Dindo grading system. Statistical analysis was performed using SPSS version 26.0, with continuous variables compared using the independent sample t-test and categorical variables using the Chi-square or Fisher's exact test. A p-value <0.05 was considered statistically significant.

Table 1. Baseline Demographic and Clinical Characteristics of Patients

Interpretation: Baseline demographic and clinical characteristics were comparable between both groups, with no statistically significant differences.

Table 2. Comparison of Perioperative Outcomes

*Statistically significant.

Interpretation: Mini-PCNL resulted in significantly lower hemoglobin loss and fewer blood transfusions, although operative time was slightly longer than standard PCNL.

Table 3. Postoperative Recovery Outcomes

*Statistically significant.

Interpretation: Patients treated with mini-PCNL experienced significantly less postoperative pain, required fewer analgesics, and had shorter hospital stays.

Table 4. Stone Clearance Outcomes

Interpretation: Stone-free rates were high and comparable between the two groups, with no statistically significant difference.

Table 5. Postoperative Complications (Clavien–Dindo Classification)

*Statistically significant.

Interpretation: Minor complications were more frequent in the standard PCNL group, particularly blood transfusion. Major complications were uncommon and showed no significant difference between the two techniques.

The present study compared the perioperative and postoperative outcomes of mini-percutaneous nephrolithotomy (mini-PCNL) and standard percutaneous nephrolithotomy (PCNL) in patients undergoing surgical treatment for renal calculi. The findings demonstrated that mini-PCNL offers significant advantages in terms of reduced hemoglobin drop, lower postoperative pain scores, shorter hospital stay, and fewer minor complications while maintaining a stone-free rate comparable to that of standard PCNL. These findings support the growing preference for mini-PCNL as a minimally invasive alternative for appropriately selected patients with moderate renal stone burden.

One of the most important findings of this study was the significantly lower hemoglobin drop observed in the mini-PCNL group. The smaller access tract used during mini-PCNL causes less renal parenchymal trauma and minimizes vascular injury, thereby reducing intraoperative blood loss. Consequently, the need for blood transfusion was also significantly lower among patients treated with mini-PCNL. These findings are consistent with previous studies, which have consistently reported reduced bleeding and lower transfusion rates with mini-PCNL compared with conventional PCNL. Reduced blood loss is particularly beneficial for elderly patients and those with pre-existing anemia or other comorbid conditions.

Postoperative pain was significantly lower in patients undergoing mini-PCNL, as reflected by lower Visual Analogue Scale (VAS) scores and reduced analgesic requirements. The smaller nephrostomy tract likely contributes to less tissue injury, resulting in decreased postoperative discomfort and earlier mobilization. Better pain control not only improves patient satisfaction but also facilitates faster recovery and reduces opioid consumption. Similar reductions in postoperative pain have been reported in several comparative studies evaluating mini-PCNL.

Hospital stay was significantly shorter in the mini-PCNL group. Early recovery, reduced pain, minimal bleeding, and lower postoperative morbidity enabled earlier discharge following surgery. Shorter hospitalization is advantageous for both patients and healthcare systems because it decreases treatment costs, lowers the risk of hospital-acquired infections, and improves bed availability. These findings further support the role of mini-PCNL as a cost-effective minimally invasive procedure.

Despite the smaller access tract, mini-PCNL achieved stone-free rates comparable to those of standard PCNL, with no statistically significant difference between the two groups. This finding indicates that reducing tract size does not compromise surgical efficacy when appropriate patient selection and modern endoscopic equipment are used. Advances in laser lithotripsy, miniaturized nephroscopes, and suction-assisted systems have greatly improved stone fragmentation and retrieval, allowing mini-PCNL to maintain excellent stone clearance rates. The slightly longer operative time observed with mini-PCNL is likely attributable to slower fragmentation and extraction of stone fragments through the narrower working channel; however, this modest increase in operative duration appears acceptable considering the overall reduction in surgical morbidity.

The incidence of postoperative complications was generally low in both groups. Minor complications, particularly postoperative fever and blood transfusion, occurred more frequently following standard PCNL, whereas major complications classified as Clavien–Dindo Grade III or higher were uncommon and did not differ significantly between the two techniques. These findings suggest that both procedures are safe when performed by experienced surgeons, although mini-PCNL provides improved perioperative safety by reducing minor adverse events.

The strengths of the present study include the relatively large sample size, standardized perioperative assessment, and evaluation of multiple clinically relevant outcomes including blood loss, pain, hospital stay, stone clearance, and complications. However, certain limitations should be acknowledged. This was a single-center observational study rather than a randomized controlled trial, introducing the possibility of selection bias. The choice of surgical technique depended partly on surgeon preference and stone characteristics. Additionally, long-term outcomes such as stone recurrence, renal function preservation, quality of life, and cost-effectiveness were not evaluated. Future multicenter randomized studies with longer follow-up periods are warranted to validate these findings and further define the optimal indications for mini-PCNL.

Overall, the results of this study indicate that mini-PCNL provides superior perioperative outcomes with comparable effectiveness to standard PCNL. The reduced blood loss, lower postoperative pain, shorter hospitalization, and similar stone-free rates suggest that mini-PCNL should be considered a preferred surgical option for appropriately selected patients requiring percutaneous management of renal calculi,

Mini-percutaneous nephrolithotomy (mini-PCNL) is a safe and effective alternative to standard PCNL for the treatment of renal calculi. It offers significant advantages, including reduced hemoglobin drop, lower postoperative pain, shorter hospital stay, and fewer minor complications, while achieving comparable stone-free rates. These findings suggest that mini-PCNL should be considered the preferred minimally invasive approach for appropriately selected patients with moderate renal stone burden. Further multicenter randomized studies with long-term follow-up are recommended to confirm these resultsA

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