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Year : 2021  |  Volume : 13  |  Issue : 3  |  Page : 226-231  

A comparative study of minimally invasive percutaneous nephrolithotomy and retrograde intrarenal surgery for solitary renal stone of 1–2 cm

Department of Urology, Institute of Nephrourology, Bengaluru, Karnataka, India

Date of Submission27-Feb-2020
Date of Acceptance21-Dec-2020
Date of Web Publication14-Jul-2021

Correspondence Address:
Dr. C S Manohar
Department of Urology, Institute of Nephrourology, Victoria hospital campus, K R Market, Bengaluru - 560 002, Karnataka
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DOI: 10.4103/UA.UA_10_20

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Background: PCNL is the treatment of choice for renal stones. But wide array of complications due to larger tract size(>20 Fr) has lead to development of improved techniques like miniPCNL(<20 Fr) and RIRS(Retrograde intrarenal surgery).
Aim and Objective:To perform a study comparing miniPCNL with RIRS for renal stones 1-2 cm with respect to stone free rate , complications and quality of life.
Materials and Methods: A prospective, randomised study was carried out our tertiary care centre, recruiting 40 patients in each group from Dec 2016 to Oct 2018. Patients demographic characteristics, operative findings, surgical outcomes and quality of life( SF-36 questionnaire) were recorded with 3 months of follow-up.
Results: RIRS has longer operative time (69.75 min > 51.58 min; p=0.003), lesser radiation exposure (p=0.012), shorter hospital stay (p =0.15), lesser blood loss and lesser post operative pain on POD1 and POD2 (p =0.005, p=0.001 respectively). RIRS group patients sufferred more post op complications (p=0.03 )of which urosepsis was most common. Stone free rate is significantly better(p =0.003) in miniPCNL group on POD1 , while SFR's at 1 month (miniPCNL-90% and RIRS -85%) and 3 month (miniPCNL- 92.5% and RIRS -87.5%) was better in miniPCNL group, but statistically insignificant.On subgroup analysis SFR in lower pole calculus was better in miniPCNL group at 1month and 3 month (p=0.008). Second intervention for stone clearance was required in 3 patients of miniPCNL and 5 patients of RIRS, out of which 4 had lower pole stone.No significant differnce was found in quality of life in both groups at 1 month.
Conclusion: MiniPCNL is a better treatment modality for higher single step stone free rate, shorter operative time and fewer postop complication. RIRS has SFR slightly less than miniPCNL but has less radiation exposure and much less post operative pain. There is no significant difference in quality of life in both groups.

Keywords: Minimally invasive percutaneous nephrolithotomy, retrograde intrarenal surgery, stone-free rate

How to cite this article:
Jain M, Manohar C S, Nagabhushan M, Keshavamurthy R. A comparative study of minimally invasive percutaneous nephrolithotomy and retrograde intrarenal surgery for solitary renal stone of 1–2 cm. Urol Ann 2021;13:226-31

How to cite this URL:
Jain M, Manohar C S, Nagabhushan M, Keshavamurthy R. A comparative study of minimally invasive percutaneous nephrolithotomy and retrograde intrarenal surgery for solitary renal stone of 1–2 cm. Urol Ann [serial online] 2021 [cited 2022 Jan 23];13:226-31. Available from: https://www.urologyannals.com/text.asp?2021/13/3/226/321343

   Introduction Top

Renal calculi are a common urological disorder. Globally, the prevalence and recurrence rates of kidney stones are increasing, probably due to climate or environment change, and increased diagnosis with limited options for effective medical treatment.[1] The lifetime prevalence of kidney stone disease is estimated at 1%–15%, varying according to age, gender, race, and geographic location.[2] Importantly, kidney stone is a recurrent disorder, with a 50% incidence of lifetime recurrence. It may lead to end-stage renal disease in around 0.6%–3.2%.[3]

With the recent technological advancements, minimally invasive surgeries such as traditional extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), laparoscopic stone surgery, and retrograde intrarenal surgery (RIRS) have become the first line in the treatment of stone disease.[4] As per the guidelines, PCNL is the gold standard for renal stones >2 cm in size; however, for stone size measuring 1–2 cm, dilemma still persists, for the best and most effective modality.[5] Hemorrhage, nephron loss, urinary extravasation, sepsis, colonic injury, pleural injury, and higher postoperative pain limit the use of PCNL as the most attractive options despite having good stone-free rates.

The most versatile newer technique is minimally invasive PCNL (also termed mini-PCNL or mini-Perc or mPCNL), devised by Helal et al. It comprises using a miniature endoscope via a small percutaneous tract (11–20 Fr).[6] It is associated with lesser postoperative complications compared to standard PCNL. RIRS (also termed flexible ureterorenoscopy) is another minimally invasive modality for managing the upper tract urinary calculi.[7] For its characteristics of minimal trauma, faster recovery, easy operability, and lesser contraindication, RIRS has been considered as a reasonable alternative for the percutaneous approaches. RIRS has problems of investment as it requires a laser machine as well as a fragile scope which is definitely costlier than usual nephroscope while mini-PCNL does not necessarily require a laser machine.

Mini-PCNL and RIRS are effective modalities for treating renal stones. The current study is conducted prospectively for comparing stone-free rates, complications, hospital stay, operative time, radiation exposure, and quality of life in both modalities for solitary renal stone of size 1–2 cm.

   Patients and Methods Top

A prospective, randomized comparative study was conducted at our tertiary care center from December 2016 to October 2018. A total of 40 patients were randomized to each group on alternate basis. Patients visiting the outpatient department with solitary renal stone of size 1–2 cm, who are willing to undergo surgery and follow-up, were included in the study.

Patients with prior upper urinary tract surgery, bleeding diathesis, morbid obesity, pregnancy, and renal failure were excluded from the study. All surgeries were performed by an expert urologist in both modalities.

All patients underwent contrast-enhanced computerized tomography-kidney ureter bladder (KUB) and routine blood investigations, including complete blood count, renal function test, and chest X-ray, before undergoing intervention. A sterile urine culture was mandatory before surgery. Written, informed, valid consent was obtained from all the patients. Following demographic data were noted.

Statistical analysis was performed using SPSS (V-20) software, with statistical significant P < 0.05. Categorical variables were analyzed using Fisher's t-test and Chi-square test, and independent t-test was used for comparison between two groups.

Minimally invasive percutaneous nephrolithotomy

Under general anesthesia, a 5 Fr ureteric catheter was placed in the pelvicalyceal system and the patient turned prone. Initial puncture was done using an 18G diamond tip needle under fluoroscopy guidance using Bull's eye technique. Tract was dilated using facial dilator up to 16 Fr and 16.5/17.5 mini-Perc Amplatz sheath was placed. 12 Fr (Karl Storz) nephroscopy was done; stone fragmentation was done using holmium laser/pneumatic lithotripsy, and fragments were removed and 12 Fr nephrostomy tube was placed.

Retrograde intrarenal surgery

RIRS was performed using Flexible urterorenoscope Olympus (URF P-6, by Olympus America) with Holmium (200 μ fiber) laser. All patients were double J (DJ) stented 2 weeks before surgery for achieving ureteric dilation for easier passage of ureteric access sheath. Intraoperatively, 9.5/11 Fr ureteric access sheath was placed at pelviureteric junction and LASER vaporization of stone was performed. Postoperative 5 Fr DJ stenting was done in all patients, which was removed after 4 weeks after confirming stone clearance.

Intraoperatively, operative time, fluoroscopy time, and complications were noted using Clavein–Dindo (CD) classification.

Postoperatively, stone-free rate (clinically insignificant residual fragment [CIRF] ≤4 mm) was assessed using X-KUB and ultrasonography KUB on postoperative day (POD) 1, 1 month, and 3 months. Stone fragment >4 mm after 1 month of first surgery was defined as failure (incomplete clearance) of surgery and second intervention was planned.

Postoperative complications as per CD Classification[8] such as hospital stay, pain score (visual analog scale),[9] fall in hemoglobin, and need for blood transfusion were noted. Patient's quality of life status at 1 month was compared using SF-36[10] questionnaire in both mini-PCNL and RIRS groups.

Standard hospital antibiotic policy was followed.

   Results Top

Baseline demographics were comparable in both groups.[Table 1].
Table 1: Demographic data

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Age ranges from 4 to 73 years. Mean age of the patients in themini-PCNL group is 35.6 years and in the RIRS group is 40.45 years.

The RIRS has higher operative time (69.75 > 51.58 min) than mini-PCNL group, which was clinically significant. The mini-PCNL arm has higher fluoroscopy time of 56.78 s with a significant P value.

Pain analysis as per visual analog scale demonstrates that patients undergoing RIRS has significantly lesser pain (P < 0.005; < 0.001) than mini-PCNL group on both POD1 and POD2. Hospital stay was shorter in the RIRS group, but it was not clinically significant. Both groups have clinically insignificant blood loss during the surgery, and none of the patients required blood transfusion. Blood loss was lesser in the RIRS group, with significant P < 0.001. No significant intraoperative complications were noted in the series. Only two patients in mini-PCNL group had pelvic perforation and were managed conservatively. RIRS group patients suffered more postoperative complications, which was statistically significant. Most patients in the RIRS group (7) developed postoperative fever/sepsis and managed conservatively with intravenous antibiotics.

Stone-free rate was significantly better (P = 0.003) in mini-PCNL group on POD1. SFR at 1 month (mini-PCNL - 90% and RIRS - 85%) and 3 months (mini-PCNL - 92.5% and RIRS - 87.5%) was also better in mini PCNL group but statistically not significant [Table 2].
Table 2: Comparison of intraoperative and postoperative surgical outcomes (matched pair analysis)

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On subgroup analysis, mini-PCNL has better SFR for lower pole stone with P = 0.008 at 3 months; while there was no significant difference in both the modalities with respect to stones in the upper pole, mid pole, or pelvis [Table 3].
Table 3: Subgroup analysis as per the location of stone

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All patients in the RIRS group compulsorily required second intervention in the form of stent removal, while three patients in the mini-PCNL group and five patients in the RIRS group required second surgery in the form of ESWL or URSL for complete stone clearance. Parameters of physical health and mental health were not statistically significant in both groups as per SF 36 [Table 4].
Table 4: Comparison of quality of life

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   Discussion Top

Our study demonstrates significant efficacy profile for both mini-PCNL and RIRS with good stone-free rate after 1 month and 3 months. The SFR here is defined as the absence of CIRF >4 mm. The SFR on POD1 is significantly better (P < 0.003) in mini-PCNL group which is in concordance with the study by Knoll et al.[11] [Table 5].
Table 5: Comparison with other studies

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1-month SFR was 90% in mini-PCNL and 85% in RIRS group as seen in the studies by Mishra et al.[12] and Knoll et al.[11] At 3 months, mini-PCNL had better SFR of 92.5% compared to 87.5% in RIRS group. Better SFR in mini-PCNL group for lower pole stones with P = 0.008(at 3 months) is attributed to poor accessibility of lower calyx with unfavorable anatomy of lower pole (more acute infundibulo-pelvic angle and narrow and longer infundibulum) which was encountered while performing RIRS. Similar findings were seen in meta-analysis by Junbo et al.[13]

Operative time and fluoroscopy time in our study were similar to the study by Akman et al.[14] The mean operative time is significantly less in mini-PCNL group (51.58 vs. 69.75 min; P < 0.003), probably due to longer time required for stone vaporization in RIRS group. In our study, the radiation exposure was more in mini-PCNL group (56.78 vs. 40.20 s; P = 0.012) due to C-arm–guided initial puncture of calyx.

Mean hospital stay was almost the same in both arms (2.85 days in mini-PCNL vs. 2.45 days in RIRS; P = 0.155). It is in contrast to series by Sabnis et al.[15] and Pelit et al. which showed significantly lesser hospital stay; 1.9 days in mini-PCNL and 1.2 days in RIRS.[16] Patients in RIRS arm were kept longer in hospital to monitor for the development of early fever/urosepsis in the initial 48 h.

There was no significant drop in hemoglobin (>1 gm/dL) in either group. The difference between two groups is statistically significant with P < 0.001, but not clinically significant, as none of the patients required blood transfusion.

Pain score as demonstrated by visual analog scale showed statistically significant difference on POD1 and POD2, with patients in RIRS group experiencing significantly lesser pain. The P = 0.005 on POD1 and <0.001 on POD2, which turn down into lesser analgesic requirement in RIRS group. These findings are in harmony with outcomes of Sabnis et al.[15] and Lee et al.[17] No significant intraoperative complication was noted in both groups except two patients who had pelvic perforation in mini-PCNL group (CD Grade I). However, significant postoperative complications were noted in both groups. As per CD classification, mini-PCNL group had 2 Grade I, 3 Grade II, and 4 Grade III complications; while RIRS group had 4 Grade 1, 7 Grade II, and 5 Grade III complications. The outcome was statistically significant (P = 0.03), with RIRS group encountering more complications. Most of the patients had postoperative fever/urosepsis within 48 h of surgery. Raised intrarenal pressure, infective stone, and intravasation lead to sepsis. Similar findings were seen in the studies by Sabnis et al. and Pan et al.,[Table 5] while contradictory results were encountered by Zengin et al.[15],[18],[19]

The patients who had CD Grade III complications had to undergo second intervention for stone clearance, indicating the failure of primary surgery. Four patients in RIRS group and 2 in mini-PCNL group underwent ESWL and one patient in each group required URSL before being declared stone free. Thirty-five patients in RIRS and six in mini-PCNL required one more intervention for stent removal.

Finally, the two groups are compared with respect to their quality of life after each intervention using SF-36 questionnaire at 1 month. Physical and mental health parameters are found no significantly different in two groups. To the best of our knowledge, this is the first study comparing “quality of life” in both subgroups in the Indian scenario.

The main limitation of the study was smaller sample size, more than one operating surgeons, nonusage of screening CT KUB after surgery for demonstrating stone clearance, and use of both pneumatic and holmium LASER as energy sources. Further studies with larger sample size and longer follow-up will consolidate our findings.

   Conclusion Top

Both mini-PCNL and RIRS have excellent outcomes for renal stones 1–2 cm in size. Mini-PCNL has a better single step stone-free rate, lesser operative time, and lesser postoperative complication. RIRS has SFR slightly less than mini-PCNL but less radiation exposure and much less postoperative pain. RIRS requires more auxiliary procedures for stone clearance and stent removal. Both procedures are equally efficacious with respect to stone clearance; however, before deciding the surgical procedure, either mini-PCNL or RIRS, patient factors, expectations, and preferences must be considered.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Bhangu GS, Bansal D, Shah AS, Lubana PS. Recurrent stone formers–metabolic evaluation: A must investigation. Int Surg J 2017;4:86-90.  Back to cited text no. 1
Sohgaura A, Bigoniya P. A review on epidemiology and etiology of renal stone. Am J Drug Discov Dev 2017;7:54-62.  Back to cited text no. 2
Ranabir S, Baruah MP, Devi KR. Nephrolithiasis: Endocrine evaluation. Indian J Endocrinol Metab 2012;16:228-35.  Back to cited text no. 3
Van Cleynenbreugel B, Kılıç í, Akand M. Retrograde intrarenal surgery for renal stones-Part 1. Turk J Urol 2017;43:112-21.  Back to cited text no. 4
Ferakis N, Stavropoulos M. Mini percutaneous nephrolithotomy in the treatment of renal and upper ureteral stones: Lessons learned from a review of the literature. Urol Ann 2015;7:141-8.  Back to cited text no. 5
[PUBMED]  [Full text]  
Sung YM, Choo SW, Jeon SS, Shin SW, Park KB, Do YS, et al. The “mini-perc” technique of percutaneous nephrolithotomy with a 14-fr peel-away sheath: 3-year results in 72 patients. Korean J Radiol 2006;7:50-6.  Back to cited text no. 6
Jiang H, Yu Z, Chen L, Wang T, Liu Z, Liu J, et al. Minimally invasive percutaneous nephrolithotomy versus retrograde intrarenal surgery for upper urinary stones: A systematic review and meta-analysis. Biomed Res Int 2017;2017:1. Available from: https://doi.org/10.1155/2017/2035851.  Back to cited text no. 7
Mitropoulos D, Artibani W, Graefen M, Remzi M, Rouprêt M, Truss M, et al. Reporting and grading of complications after urologic surgical procedures: An ad hoc EAU guidelines panel assessment and recommendations. Eur Urol 2012;61:341-9.  Back to cited text no. 8
Chung JM, Kim TN, Lee KM, Baik SW, Lee SD. Comparison of Pain Control method and assessment on postoperative pain in pediatric urological surgery of penoscrotal and inguinal regions. Korean J Urol 2007;48:163-70.  Back to cited text no. 9
Donnally CJ 3rd, Gupta A, Bensalah K, Tuncel A, Raman J, Pearle MS, et al. Longitudinal evaluation of the SF-36 quality of life questionnaire in patients with kidney stones. Urol Res 2011;39:141-6.  Back to cited text no. 10
Knoll T, Jessen JP, Honeck P, Wendt-Nordahl G. Flexible ureterorenoscopy versus miniaturized PNL for solitary renal calculi of 10-30 mm size. World J Urol 2011;29:755-9.  Back to cited text no. 11
Mishra S, Sharma R, Garg C, Kurien A, Sabnis R, Desai M, et al. Prospective comparative study of miniPerc and standard PNL for treatment of 1 to 2 cm size renal stone. BJU Int 2011;108:896-9.  Back to cited text no. 12
Junbo L, Yugen L, Guo J, Jing H, Ruichao Y, Tao W, et al. Retrograde intrarenal surgery vs. Percutaneous nephrolithotomy vs. Extracorporeal shock wave lithotripsy for lower pole renal stones 10-20 mm : A Meta-analysis and systematic review. Urol J 2019;16:97-106.  Back to cited text no. 13
Akman T, Binbay M, Ozgor F, Ugurlu M, Tekinarslan E, Kezer C, et al. Comparison of percutaneous nephrolithotomy and retrograde flexible nephrolithotripsy for the management of 2-4 cm stones: A matched-pair analysis. BJU Int 2012;109:1384-9.  Back to cited text no. 14
Sabnis RB, Jagtap J, Mishra S, Desai M. Treating renal calculi 1-2 cm in diameter with minipercutaneous or retrograde intrarenal surgery: A prospective comparative study. BJU Int 2012;110:E346-9.  Back to cited text no. 15
Pelit ES, Atis G, Kati B, Akin Y, Çiftçi H, Culpan M, et al. Comparison of mini-percutaneous nephrolithotomy and retrograde intrarenal surgery in preschool-aged children. Urology 2017;101:21-5.  Back to cited text no. 16
Lee JW, Park J, Lee SB, Son H, Cho SY, Jeong H, et al. Mini-percutaneous nephrolithotomy vs retrograde intrarenal surgery for renal stones larger than 10 mm: A Prospective randomized controlled trial. Urology 2015;86:873-7.  Back to cited text no. 17
Pan J, Chen Q, Xue W, Chen Y, Xia L, Chen H, et al. RIRS versus mPCNL for single renal stone of 2-3 cm: Clinical outcome and cost-effective analysis in Chinese medical setting. Urolithiasis 2013;41:73-8.  Back to cited text no. 18
Zengin K, Tanik S, Karakoyunlu N, Sener NC, Albayrak S, Tuygun C, et al. Retrograde intrarenal surgery versus percutaneous lithotripsy to treat renal stones 2 3 cm in diameter. Biomed Res Int 2015;2015:914231.  Back to cited text no. 19


  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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