Randomized Controlled Trial to Compare the Operative Outcomes and Complications of Mini-Percutaneous Nephrolithotomy (mini-PCNL) Versus Standard PCNL


About this study

The purpose of this study is to compare the operative outcomes and complications of mini-percutaneous nephrolithotomy (mini-PCNL) versus standard PCNL for renal stones.

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. There is no guarantee that every individual who qualifies and wants to participate in a trial will be enrolled. Contact the study team to discuss study eligibility and potential participation.

Inclusion Criteria:

  • Patients with planned PCNL and a preoperative CT scan.
  • Urologist obtained access and prone positioning during surgery.
  • Tract dilation performed either using balloon dilator or a single step mini-PCNL dilation.
  • Age: ≥ 18 years old.
  • Stone size: 10-25mm.
  • Male and female patients.
  • Patients of all ethnic backgrounds.
  • Capable of giving informed consent.
  • Capable and willing to fulfill the requirements of the study.
  • Pre-existing indwelling nephrostomy tube or ureteral stent permitted.

Exclusion Criteria: 

  • Anticoagulated or history of coagulopathy (with the exception of daily 81 mg aspirin).
  • Conversion to open procedure.
  • Multiple access tracts.
  • Inability to give informed consent or unable to meet requirements of the study for any reason.

Eligibility last updated 9/21/21. Questions regarding updates should be directed to the study team contact.


Participating Mayo Clinic locations

Study statuses change often. Please contact the study team for the most up-to-date information regarding possible participation.

Mayo Clinic Location Status Contact

Scottsdale/Phoenix, Ariz.

Mayo Clinic principal investigator

Mitchell Humphreys, M.D.

Open for enrollment

Contact information:

Vy Nguyen CCRP



More information


  • We aimed to compare the outcomes of mini-percutaneous nephrolithotomy (mPNL) and standard PNL techniques in the treatment of renal stones ≥ 2 cm. The study was designed as a randomized prospective study between January 2016 and April 2017. The patients with a kidney stone ≥ 2 cm were included in the study. Patients who had uncorrectable bleeding diathesis, abnormal renal anatomy, skeletal tract abnormalities, pregnant patients and pediatric patients (< 18 years old) were excluded from the study. The remaining patients were randomly divided into two groups as standard PNL and mPNL. For both group, demographic data, stone characteristics, operative data and postoperative data were recorded prospectively. The study included 160 consecutive patients who had kidney stone ≥ 2 cm. Of these, patients who met the exclusion criteria and patients who had missing data were excluded from the study. Remaining 97 patients were randomly divided into two groups as mPNL (n: 46) and standard PNL (n: 51). The mean age was 46.9 ± 13.7 and 47.4 ± 13.9 years for mPNL group and sPNL group, respectively. According to Clavien-Dindo classification, no statistical difference was detected between the groups in terms of complication rates (p 0.31). However, the rates of hemoglobin drop and transfusion rates were significantly in favour of mPNL (p 0.012 and p 0.018, respectively). Nephrostomy time and hospitalization time was found to be significantly shorter in mPNL group (p 0.017 and p 0.01, respectively). The success rate in the mPCNL group was higher than standard PNL group, however, this difference was statistically insignificant (76.5 vs 71.7%, p 0.59). Both mPNL and standard PNL are safe and effective treatment techniques for the treatment of kidney stones of ≥ 2 cm. Although there was no significant difference in success rates of both techniques; nephrostomy time, hospitalization time, bleeding and transfusion rates were in favour of mPNL. Read More on PubMed
  • To determine how sheath and endoscope size affect intrarenal pelvic pressures and risk of postoperative infectious complications comparing "Mini" vs "Standard" percutaneous nephrolithotomy (PCNL). Read More on PubMed
  • Renal pelvic pressure may vary during percutaneous nephrolithotomy. We sought to determine the relationship of postoperative pain to endoscope caliber, renal pelvic pressure and hospital stay. Read More on PubMed
  • To assess the safety and efficacy of minimally invasive percutaneous nephrolithotomy (mPCNL) as compared to standard PCNL (sPCNL) for management of 2-3-cm renal stones in the flank-free modified supine position. Between September 2010 and December 2013, 150 patients (168 renal units) with 2-3-cm renal stones were prospectively randomized into two treatment groups; Group A (75 patients/87 renal units) treated by mPCNL and Group B (75 patients/81 renal units) treated by sPCNL. In both groups, the patients were placed in the flank-free modified supine position. In mPCNL group, the tract was dilated up to 16.5 F whereas in sPCNL group the tract was dilated up to 30 F. Both groups were compared regarding several perioperative parameters. No significant difference was recorded among both groups regarding fluoroscopy time (4.3 ± 1.3 vs 4.8 ± 2.1 min, p = 0.06), operative time (83.2 ± 17.3 vs 78.6 ± 24.4 min, p = 0.16), hospital stay (4.3 vs 4.5 days, p = 0.76), VAS score (3.2 ± 0.6 vs 3.3 ± 0.8, p = 0.36) and need for analgesia. The mean drop in hemoglobin level and the incidence of bleeding that necessitated blood transfusion were significantly lower in the mPCNL group (0.6 ± 0.1 vs 1.9 ± 1.1 g/dl, p < 0.0001 and 1.2 vs 9.8%, p = 0.03, respectively). Although the stone-free rate was higher in the sPCNL group, but this was statistically insignificant (97.1 vs 95.4%, p = 0.86). Mini-PCNL is effective for managing renal calculi with comparable operative time and stone-free rate to standard PCNL with the merit of higher safety due to lower incidence of bleeding that necessitates blood transfusion. Read More on PubMed
  • This study was proposed to compare the clinical effectiveness of mini-tract percutaneous nephrolithotomy (MPCNL) with standard-tract percutaneous nephrolithotomy (SPCNL) and verify whether MPCNL is associated with both higher renal pelvic pressure (RPP) and incidence of postoperative fever. A total of 228 patients with kidney stone were randomly allocated to the MPCNL group (n=114) and SPCNL group (n=114). Both intraoperative and postoperative indexes along with the incidence of complications were compared between the two treatment groups. RPP was measured using a baroreceptor which was connected to an open-ended ureteric catheter during the operation of percutaneous nephrolithotomy. The MPCNL group exhibited significantly longer average operation time, more average amount of flush water, and lesser average amount of bleeding during the operation than the SPCNL group (p<0.05). Moreover, significantly lesser average amount of postoperative serum creatinine, shorter average hospital stay, and more average amount of postoperative hemoglobin were observed in the MPCNL group than in the SPCNL group (p<0.05). MPCNL were more applicable to clear caliceal stones (p<0.05), whereas SPCNL were more effective for the removal of simple pelvic stones. The difference in the incidence of postoperative fever between the two treatment groups also appeared to be significant (p<0.05). Logistic regression provided solid evidence that both RPP and its accumulation time at which RPP≥30 mmHg significantly affected the incidence of postoperative fever. MPCNL was correlated with both higher RPP and increased likelihood of postoperative fever compared with SPCNL. Read More on PubMed
  • This Guideline is intended to provide a clinical framework for the surgical management of patients with kidney and/or ureteral stones. The summary presented herein represents Part I of the two-part series dedicated to Surgical Management of Stones: American Urological Association/Endourological Society Guideline. Please refer to Part II for an in-depth discussion of patients presenting with ureteral or renal stones. Read More on PubMed
  • We evaluated the impact of intraoperative irrigation pressures on the risk of systemic inflammatory response after percutaneous nephrolithotomy. Read More on PubMed
  • To assess the association of systemic inflammation and outcome after major abdominal surgery. Read More on PubMed
  • To present a novel miniature endoscopic system designed to improve the safety and efficacy of percutaneous nephrolithotomy, named the 'super-mini percutaneous nephrolithotomy' (SMP). Read More on PubMed
  • To report the haemodynamic, electrolyte, and metabolic changes of a prospective clinical trial comparing minimally invasive percutaneous nephrolithotomy (MPCNL) with percutaneous nephrolithotomy (PCNL) for renal stones. Read More on PubMed
  • To describe our newly developed technique for the removal of renal stones, which we have called ultra-mini percutaneous nephrolithotomy (UMP). Read More on PubMed
  • To, first, propose a novel scoring system to standardize reporting for percutaneous nephrolithotomy because the instruments currently available to predict the percutaneous nephrolithotomy outcomes are cumbersome, not validated, and of limited clinical utility; and, second, assess and predict the stone-free rates and perioperative parameters applying S.T.O.N.E. nephrolithometry. Read More on PubMed
  • The study compared characteristics and outcomes in patients with solitary and bilateral kidneys who were treated with percutaneous nephrolithotomy (PCNL) in the Clinical Research Office of the Endourological Society (CROES) PCNL Global Study. Read More on PubMed
  • To our knowledge we report the first technical feasibility and safety study of 1-step percutaneous nephrolithotomy using the previously described 4.85Fr all-seeing needle (PolyDiagnost, Pfaffenhofen, Germany). We defined microperc as modified percutaneous nephrolithotomy in which renal access and percutaneous nephrolithotomy are done in 1 step using the all-seeing needle. Read More on PubMed
  • There has been continuing controversy regarding multiple tracts in a percutaneous nephrolithotomy (PCNL) session that may bring more complications, especially severe bleeding need for transfusion, even nephrectomy. Little tracts may bring less trauma to renal parenchyma than standard PCNL tracts. We carried minimally invasive PCNL (MPCNL) in treating staghorn calculi with multiple 16Fr percutaneous tracts in a single session, in an attempt to get high stone free with little trauma, and compared the morbidity of standard PCNL procedures in a prospective trial. A total of 54 consecutive patients with staghorn calculi were prospectively randomized for MPCNL (29) and PCNL (25). The size and location of stone, operative parameters, number of tracts, stone-free rate, operating time, hospital stay and complications were analyzed. In MPCNL group, a total of 67 percutaneous tracts were established in 29 renal units, while 28 tracts in 25 renal units in PCNL group. Compared to PCNL, MPCNL was associated with higher clearance rate (89.7 vs. 68%, p = 0.049), less chance need for adjunctive procedure of SWL or second-look PCNL (24.1 vs. 60%, p = 0.007), while a similar complication rate (37.9 vs. 52%, p = 0.300). In conclusion, with the development of instruments and increased experience, judiciously made multiple percutaneous tracts in a single session of MPCNL for treating staghorn calculi were safe, feasible and efficient with an acceptable morbidity. Read More on PubMed
  • • To compare the content validity (realism and usefulness) of percutaneous renal access (PRA) obtained on a live porcine model and a high-fidelity computer-based surgical simulator (PERC Mentor, Simbionix; Lod, Israel) in our skills laboratory for trainees interested in PRA training, so as to determine which of the two is a more appropriate and effective training model. Read More on PubMed
  • The aim of this study was to assess the efficacy, safety, and morbidity of minimally invasive tract in percutaneous nephrolithotomy (Mini-PCNL) for renal stones in comparison with the standard PCNL. Read More on PubMed
  • High renal pelvic pressure brings systemic absorption of irrigation fluid containing bacteria or endotoxins, which leads to postoperative fever. We inspected the renal pelvic pressure (RPP) in vivo during minimally invasive percutaneous nephrolithotomy (MPCNL) to investigate whether a 14- to 18-French percutaneous tract and perfusion would bring high RPP and postoperative fever. Read More on PubMed
  • A classification (modified Clavien system) has been proposed to grade perioperative complications. We reviewed our experience with percutaneous nephrolithotomy (PNL), grading the complications according to this new classification. Read More on PubMed
  • This review focuses on a step-by-step approach to percutaneous nephrolithotomy (PNL) and its complications and management. Read More on PubMed
  • The aim of this retrospective study was to evaluate the results of our miniperc series through comparison with results from standard percutaneous nephrolithotomy (PNL) and tubeless PNL series in the treatment of stones <2 cm in diameter. Read More on PubMed
  • Although quality assessment is gaining increasing attention, there is still no consensus on how to define and grade postoperative complications. This shortcoming hampers comparison of outcome data among different centers and therapies and over time. Read More on PubMed
  • Significant early postoperative discomfort after percutaneous procedures is usually secondary to nephrostomy tubes and externalized ureteral catheters. We describe our modification of the traditional percutaneous nephrolithotomy (PCNL) approach that we name "totally tubeless PCNL." Read More on PubMed
  • Large amounts of irrigating fluid are used during percutaneous nephrolithotomy (PCNL). This use may be associated with migrating calculus debris, infection, and fluid absorption. This study evaluated the presence of fluid absorption during PCNL, its clinical and biochemical significance, and maneuvers to reduce it. Read More on PubMed
  • The disadvantages of standard percutaneous nephrolithotomy (PCNL) as compared with ureteroscopy or extracorporeal shock-wave lithotripsy include increased blood loss, greater pain, and longer hospital stay. A 13-Fr "mini-perc" technique using a ureteroscopy sheath for PCNL was developed in an attempt to address these drawbacks. Nine "mini-percs" have been performed in patients aged 40-73 years with stone burdens of < or = 2 cm2. On average, patients had 1.4 stones with a cross-sectional area of 1.5 cm2. The mean total procedure time, estimated blood loss, and hematocrit decrease were 176 min, 83 ml, and 6.6%, respectively. On average, patients used 14 mg of parenteral morphine and stayed 1.7 days in the hospital. There was no procedure-related complication or transfusion. Eight of nine kidneys (89%) were stone-free on early follow-up at a mean of 3.8 weeks. As compared with standard PCNL, the "mini-perc" technique has similar early success rates in selected patients and may offer advantages with respect to hemorrhage, postoperative pain, and shortened hospital stays. Read More on PubMed