Abstract
Background
Lower calyceal anatomy makes the stone clearance a difficult task across all treatment formats. Improvement in optics and miniaturization of instruments have offered an effective and safer alternative to percutaneous nephrolithotomy (PCNL). The study was conducted to compare the efficacy and complications associated with mini-PCNL vs standard-PCNL.
Methods
The study was a randomized control trial to compare mini-PCNL vs standard-PCNL for treatment of 1 to 2 cm inferior calyceal stones. Objectives were to compare peri-operative bleeding, operative-time, post-op analgesia requirement, hospital-stay and stone-free rate at 1 month. Patients with 1–2 cm inferior calyceal stones were included. Morbidly obese individuals, patients with renal malformation and paediatric age group were excluded.
Result
One hundred and fifty seven patients were included out of 207 who underwent PCNL in this period. 80 underwent mini-PCNL and 77 standard-PCNL. Mini-PCNL scored over standard in hospital-stay (3.96 vs 4.73 days), post-operative analgesia requirement (2.58 vs 5.55 gms) and drop in Hb (0.59 vs 0.81 gm/dl). Even stone clearance rate was better for mini-PCNL (87.01% vs 93.75%). Mean surgery time was marginally better for standard-PCNL (44.03 vs 43.33 mins). Stone clearance rate and average surgery time were comparable with no statistically significant difference in the two groups. Analgesia requirement was statistically lower in mini-PCNL due to smaller tract and tubeless-PCNL. Hospital stay was statistically lower in mini-PCNL due to lesser post-operative pain. Peri-operative bleeding was statistically lower in mini-PCNL due to smaller track dilatation and lesser tract bleeding.
Conclusions
Mini-PCNL is a safe and effective treatment option in the management of 1–2 cm inferior calyceal stones with significantly less bleeding, shorter hospital-stay and analgesia requirement as compared to standard-PCNL with comparable stone clearance rates.
Keywords: Calculi, Fragments, Inferior Calyx, Mini-PCNL, Standard-PCNL
Introduction
Urinary tract stones and stone disease have affected mankind for ages and have significant long-term socio-economic implications.1,2 The management of renal calculi has evolved considerably over the decades. The ideal treatment for such a condition would be complete stone clearance in a single session without any renal damage or stone recurrence. Presently, we remain short of this, but the available treatment modalities are continuously evolving over time to improve efficacy and minimize complications. Extracorporeal Shock Wave Lithotripsy (ESWL) and flexible ureteroscopy (RIRS) are the two main modalities for treating renal calculi less than 2 cm, and percutaneous nephrolithotomy (PCNL) is the modality for treating calculi more than 2 cm.3 PCNL, first described in 1976, had become a treatment of choice for all-sized renal calculi before the introduction of other treatment modalities. Over the past two decades, advances in fiberoptics and energy sources have allowed modifications in the technique and instrumentation of PCNL to reduce its morbidity and improve efficacy. Studies showed that the success rate at 3 months for lower pole calculi was statistically higher for PCNL as compared to other modalities.4 More so, PCNL has a reduced risk of febrile urinary tract infection, a higher stone-free rate, and a shorter treatment time.4 The drawbacks of PCNL are complications associated with surgery and anesthesia.4 The main risk of PCNL is intraoperative and perioperative hemorrhage that may require blood transfusion in around 11–14% of the cases.4 Traditionally, PCNL required a 30-Fr tract for renal access; however, the recent development of smaller-sized nephroscopes ensured minimal damage to the renal parenchyma without diminishing its therapeutic efficacy.5, 6, 7, 8
The anatomy of lower calyces makes stone clearance from them a difficult task across all treatment formats. ESWL-led fragmentation can leave fragments in the dependent calyces, especially if calyceal and infundibular anatomy is unfavorable. With RIRS, the placement of scope, negotiating the acute angle, and positioning of scope for targeting the energy or picking up with a basket may become an uphill task, and for PCNL, the initial puncture and dilatation remain challenging. This has led to an appreciable controversy over the last few decades over ascertaining which modality is better.9 Presently, the decision usually remains with the urologist to pick up the correct modality based on stone size, location, calyceal anatomy, and his own experience.10
Overall lower calyceal stone burden is the main driver for treatment decisions.11,12 Stone burden of size 2 cm or larger are best approached with PCNL, as collective evidence shows that it offers a considerably higher stone-free rates. For stone burdens of 1 cm–2 cm, PCNL remains the most efficient treatment option, although it is more invasive and preferred when prior Ureterorenoscopy (URS)/RIRS/ESWL fails. RIRS/ESWL is preferred if the stone is <1 cm.11
In general, mini-PCNL has demonstrated equivalent stone clearance to standard-PCNL12, 13, 14, 15, 16, 17 but longer operative time.12, 13, 14, 15, 16, 17 Most of the studies showed a smaller hemoglobin drop, a lesser analgesia requirement, and a shorter hospital stay in patients who underwent mini-PCNL.12, 13, 14, 15, 16, 17 Presently, there is not much Indian data available on this topic that has compared all these postoperative outcomes together, and an additional study with a larger sample size is necessary to better evaluate these two techniques. Therefore, we have compared mini-PCNL with standard PCNL for the treatment of 1-2 cm sized inferior stones, and postoperative outcomes were analyzed.
Material and methods
The present study was a randomized control trial to compare mini-PCNL vs standard-PCNL for treatment of 1–2 cm-sized inferior calyceal renal stones. The objectives were to compare the perioperative bleeding and operative time, postoperative analgesia requirement, hospital stay, and residual stone at one month in the patients treated with mini (18Fr) versus standard-PCNL (24Fr).
The study was conducted at Command Hospital (Eastern Command), Kolkata, and Army Hospital (R&R), Delhi Cantt.
Inclusion criteria were patients presenting with 1–2 cm-size inferior calyceal renal stones. Exclusion criteria were pediatric patients (<16 yrs), active urinary tract infection, renal malformation, uncorrected coagulopathy, and morbid obesity.
All guidelines as per the Declaration of Helsinki and good clinical practice guidelines were followed. Institutional Ethical Committee (IEC) approval was obtained, as well as patient informed consent was obtained, and procedural details were explained to the patients. The limitations/advantages of both procedures were also explained to the patients. All patients agreed to undergo either of the procedures as per the randomization technique. The demographic data of all the patients were recorded in an Excel sheet, and a Student t test was used to compare the data in two groups.
The stone size was defined by the maximum length of the stone on the preoperative Ultrasound kidney, ureter & bladder (USG KUB)/Intra Venous Pyelogram (IVP).
The location of the stone was confirmed on the USG KUB/IVP. Patients with stones located in the inferior calyx were included in the study. Patients were randomized into two groups using the sealed envelope method. Anesthesia fitness was taken, and patients in ASA Gd I/II were taken up for the surgery. All patients were reviewed during the intraoperative, post-operative, and 30-day period from the day of surgery.
Perioperative bleeding was calculated as a fall in hemoglobin (Hb) 72 h after the surgery.
The surgery time was calculated in minutes from the first fluoroscopy taken for contrast/air pyelogram to suture placement in mini-PCNL and suturing of the nephrostomy tube in standard-PCNL.
The postoperative analgesia requirement was calculated as Inj Paracetamol (PCM) in gms taken by the patient in the postoperative period. Analgesia was given on demand only in the postoperative period.
The hospital stay was calculated in days, and patients were discharged if there was no analgesia requirement and their urine was clear for 24 h.
All patients underwent USG KUB and radiograph KUB for 1 month, and any residual calculus, if present, was recorded. The stone clearance was said to be complete when there were no fragments >4 mm seen in USG and radiograph KUB.
Operative techniques
The patients were operated on under spinal/general anesthesia in both groups. In the lithotomy position, under fluoroscopic guidance, a ureteric catheter and Foley's catheter were placed, and then patients were placed in the prone position. Under fluoroscopic guidance and an air pyelogram, the predecided calyx was punctured by triangulation/free-hand technique. 0.035″ guide wire placed in pelvis/calyx/ureter. Serial dilatation was done using Amplatz dilators up to 18 Fr, and an 18 Fr disposable sheath was placed over the dilator.
The position of the sheath was confirmed under a fluoroscope, and a 12-Fr nephroscope was used to localize the stone, and fragmentation done using a Hol:YAG laser. Fragments were removed, and an antegrade 6 Fr double-J stent was placed in all cases. The Amplatz sheath was removed, and a single suture was taken at the puncture site.
Patients were given 3 doses of antibiotics, and in case of fever, antibiotics were given till the fever subsided. The Double-J stent was removed as an outpatient department (OPD) procedure at 4 weeks.
In standard-PCNL, the initial procedure was the same, but serial dilatation was done up to 24 Fr, and a 24 Fr, metallic sheath was placed over a 24 Fr Amplatz dilator. Then the stone was fragmented using lithoclast, fragments were removed, and an ante-grade 6 Fr double-J stent was placed in all cases. The Amplatz sheath was removed over the 16 Fr nephrostomy, and a suture was taken to fix it. In the postoperative period, the nephrostomy tube was removed after 24–48 h, and further management and follow-up were the same in both groups.
Statistical analysis
Data were collected and put in a master chart in MicrosoftExcel© format. Statistical analysis was done using SPSS 20 software®. A Student t test was used to compare data in two groups. The P value was calculated, and a value <0.05 was taken as statistically significant. If any statistically significant difference could be detected, the same was analyzed to find out the cause and compared with published studies.
Results
In the present study, 207 patients underwent standard-PCNL/mini-PCNL during the study period. Out of these 207 patients, 157 had 1–2 cm inferior calyceal calculus and were included in the study. 50 patients were excluded to various exclusion criteria. Eighty patients underwent -tubeless PCNL, and seventy-seven underwent standard-PCNL (Fig. 1).
Fig. 1.
Patient distribution.
Out of 157 patients, 19 were female and 138 were males. In the mini-PCNL, there were 10 (12.5 %) females and 70 (87.5 %) males, and in the standard-PCNL, there were 9 (11.7 %) female patients and 68 (88.3 %) men. The age of the patients varied from 18 yrs to 73 yrs. In mini-PCNL, it varied from 18 yrs to 68 yrs, with a mean of 38.49 yrs, whereas in standard-PCNL, it varied from 19 yrs to 73 yrs, with a mean of 38.77 yrs. The age distribution in the two groups was equal and statistically insignificant.
The surgery time in standard-PCNL ranged from 30 min to 65 min, whereas in mini-PCNL it varied from 30 min to 70 min. The average surgery time in standard-PCNL was 44.03 min as compared to 43.33 min in mini-PCNL and this difference was statistically not significant (Table 1). The hospital-stay in standard-PCNL varied from 3 days to 11 days whereas in mini-PCNL it was 2 days to 9 days. The mean hospital stay in standard-PCNL was 4.73 days as compared to 3.96 days in mini-PCNL. The mean hospital stay was statistically lower in mini-PCNL (Table 1). The postoperative analgesia requirement in standard-PCNL varied from 2 gms to 9 gms, whereas in mini-PCNL it varied from 0 gms to 6 gms. The mean requirement of Inj PCM was 5.5 gms in standard-PCNL as compared to 2.58 gms, in mini-PCNL, and it was significantly lower in mini-PCNL (Table 1). The fall in Hb in standard-PCNL varied from 0.1 gm/dl, to 2.6 gm/dl whereas in mini-PCNL varied from 0 gm/dl to 3.7 gm/dl as compared to preoperative Hb. The mean fall in Hb in standard-PCNL was 0.81 gm/dl as compared to 0.59 gm/dl in mini-PCNL. The blood loss in standard-PCNL was significantly higher as compared to mini-PCNL (Table 1). Ten patients had residual calculi in standard-PCNL, and out of these patients, three had intraoperative bleeds, for which the procedure was abandoned. Six patients had residual calculi in mini-PCNL, and out of these, in one patient, calculi were not localized intraoperatively. The mean stone clearance rate was 87.01% in standard-PCNL as compared to 93.75% in mini-PCNL, which was statistically not significant (Table 1).
Table 1.
Comparison of outcomes in two groups.
| No. of patients | M:F ratio | Mean age (Yrs) | Avg surgery time(mins) | Hospital stay (Days) | Analgesia (Gms) | Fall in Hb(gm/dl) | Stone clearance | |
|---|---|---|---|---|---|---|---|---|
| Standard-PCNL | 77 | 7.5:1 | 38.77 | 44.03 | 4.73 | 5.55 | 0.81 | 87.01 % |
| Mini-PCNL | 80 | 7:1 | 38.49 | 43.33 | 3.96 | 2.58 | 0.59 | 93.75 % |
| P- value | 0.79 | 0.000142371 | 0.001 | 0.03 | 0.16 |
Discussion
The management of renal calculi has evolved considerably over decades. The ideal treatment would be complete stone clearance in a single session without significant patient morbidity or stone recurrence. Over the years, many modifications have occurred in the technique and instrumentation to reduce its morbidity and improve efficacy. In the present study, mini-PCNL was compared with standard-PCNL for the management of 1-2 cm sized inferior calyceal stones, and outcomes were compared.
The present study had 12.1% females as compared to 87.9% males. In contrast to most studies where there is a slight male preponderance (Zeng et al.15 58.3% males and 41.7% females), our study had a significant male preponderance (87.9% males and 12.1% females) (Table 1). This was probably because this study was conducted in a male-dominated defense setup. The stone disease is commonly seen in middle age. In the present study, age varied from 18 yrs to 73 yrs. In mini-PCNL, the mean age was 38.49 yrs, whereas in standard-PCNL, it was 38.77 yrs, which was equal and statistically insignificant.
Many series with mini PCNL reported a stone-free rate in the range of 60–90 %.5, 6, 7,16,18 In one of these studies, the stone-free rate assessment was done as early as day 2 post-operatively.18 It is apparent that stone fragments are known to be present after laser lithotripsy/lithoclast and it is worthwhile to see if they are clinically significant at 1 month. For this reason, we assessed clearance at 1 month.
The stone clearance was said to be complete when there were no fragments >4 mm seen on USG and radiograph KUB done at 1 month. The stone clearance rate was 87.01% in standard-PCNL as compared to 93.75% in mini-PCNL, which was statistically insignificant (Table 1).
In a comparative analysis done by Zeng et al.15 of >12,000 cases, the stone clearance rate was 82.5% in standard-PCNL as compared to 85.2 % in mini-PCNL. The stone clearance rate of standard-PCNL is comparable with the studies tabulated in Table 2 except in the review article published by Ferakis et al.12 The possible reason could be the inclusion of studies with a larger mean size of stones (>20 mm) in standard-PCNL in that review article. The stone clearance rate of mini-PCNL (>90 %) in our study was comparable with the studies quoted in Table 2. The possible reason for the higher clearance rate in the present study was due to use of suction and baskets to remove all the fragments and ensure complete fluoroscopic clearance. The reason for the lower clearance rate in standard-PCNL was due to procedure abandonment in 3 patients due to intraoperative bleeding.
Table 2.
Comparison of surgical outcomes with corresponding studies.
| Present study | Sabnis et al.14 | Zeng et al.15 | Ferakis et al.12 | Khadgi et al.13 | ||
|---|---|---|---|---|---|---|
| Stone clearance | Standard PCNL | 87.01 % | Not recorded | 82.5 % | 70.0 % | 83 % |
| Mini PCNL | 93.75 % | 85.7 % | 85.2 % | 90.8 % | 88.6 % | |
| P Value | 0.16 | – | 0.23 | <0.05 | 0.10 | |
| Operative time | Standard PCNL | 44.03 | Not recorded | 103 | 53.7 | 99.6 |
| Mini PCNL | 43.33 | Not recorded | 116 | 62.4 | 90 | |
| P Value | 0.79 | – | 0.052 | Not calculated | 0.071 | |
| Analgesia requirement | Standard PCNL | 5.55 | Not recorded | Not recorded | 70.2 g (tramadol) | Not recorded |
| Mini PCNL | 2.58 | Not recorded | Not recorded | 55.4 g (tramadol) | Not recorded | |
| P Value | 0.001 | – | – | <0.05 | – | |
| Hospital stay | Standard PCNL | 4.73 | Not recorded | 9.4 ± 6.0 | 4.8 | 6 |
| Mini PCNL | 3.96 | Not recorded | 8.4 ± 2.5 | 3.2 | 3 | |
| P Value | 0.000142371 | – | Not calculated | <0.05 | <0.05 | |
| Fall in Hb (gm/dl) | Standard PCNL | 0.81 | Not recorded | Not recorded | 1.3 | 1.5 |
| Mini PCNL | 0.59 | Not recorded | Not recorded | 0.8 | 1.0 | |
| P Value | 0.03 | – | – | <0.05 | Not calculated |
The most important drawback of mini PCNL is lengthy operative time9,15 due to diminished intraoperative field visibility, the need for fragmentation by laser/lithoclast into very small stones suitable for small graspers and/or baskets, and the small sheath. The increased operative time is also contributed by the prolonged intracorporeal lithotripsy time required by the Holmium laser. In our study, we used lasers for stone fragmentation along with variable suction energy to remove the fragments.
The average surgery time in standard-PCNL was 44.03 min as compared to 43.33 min in mini-PCNL, and this difference was statistically not significant (Table 1). The surgery time of mini-PCNL and standard-PCNL was compared in the limited studies only, and few are tabulated in Table 2. In a review article published by Ferakis et al.12 the operative time of mini-PCNL was greater than standard-PCNL, but no statistical analysis was done. In the study by Khadgi et al.13 and Zeng et al.15 the operative time of mini-PCNL and standard-PCNL was comparative and statistically insignificant; however, they had significantly longer operative time in both groups as compared to the present study, possibly due to the inclusion of partial and complete Staghorn calculus in both groups. If we compare both procedures for comparative-size stones, the operative was also comparative.
The primary aim of devising the mini-PCNL technique was to reduce nephron loss and complications, especially bleeding, and generally, it was associated with less procedure-related pain. Some studies support the general understanding that postoperative pain depends more on the presence of a nephrostomy rather than on the tract's size.19, 20, 21
The mean analgesia requirement of Inj PCM was 5.55 gms in standard-PCNL as compared to 2.58 gms in mini-PCNL, which was significantly lower in mini-PCNL (Table 1).
The analgesia requirement in standard-PCNL and mini-PCNL was compared in limited studies only (Table 2). On review of literature, we could find only review articles published by Ferakis et al.12 where less analgesia was required in mini-PCNL as compared to standard-PCNL. The lesser analgesia requirement in mini-PCNL was due to the smaller tract, nonplacement of the nephrostomy and small size of the sheath.
The mean hospital stay in standard-PCNL was 4.73 days, whereas it was 3.96 days in mini-PCNL, which was statistically lower in mini-PCNL (Table 1).
The hospital stay in two groups was compared with the corresponding studies (Table 2). The possible reason for a longer hospital stay in standard-PCNL was the higher analgesia requirement and more complications reported in standard-PCNL as compared to mini-PCNL. Significantly shorter hospital stays in mini-PCNL were reported by Khadgi et al.13 and Ferakis et al.12 Zeng et al.15 reported comparative hospital stay in both groups, possibly due to large stones and multiple punctures in mini-PCNL.
Perioperative bleeding is the main fear for the operating surgeon, as he may have to abandon the procedure, which may be life-threatening. The mean fall in Hb in standard-PCNL was 0.81 gm/dl as compared to 0.59 gm/dl in mini-PCNL, which was significantly higher in standard-PCNL (Table 1).
The blood loss in two groups was compared with the corresponding studies (Table 2). If we compare the present study with the study done by Khadgi et al.13 and review article published by Ferakis et al.12 the blood loss was significantly lower in the mini-PCNL as compared to the standard-PCNL. The reason for lower blood loss in mini-PCNL was due to track dilatation up to 18 Fr only and lesser tract bleeding.
Limitations of study: Stone clearance was confirmed by a radiograph and USG, but a computer tomography (CT) scan could have been the ideal investigation in both pre- and post-operative stone evaluation however, it was not feasible due to the high patient load and single a CT scan machine available at our center.
Conclusion
Mini-PCNL is a safe and effective treatment option in the management of 1–2 cm inferior calyceal stones. As compared to standard-PCNL, there is significantly less blood loss and analgesia requirement when patients are managed with mini-PCNL.
Patients also have significantly shorter hospital stays as compared to standard-PCNL. The stone clearance rate is comparable in both groups. There is enough evidence to support the idea that small renal stones can be effectively and efficiently managed with mini-PCNL.
Recommendation
Mini-PCNL is safe and effective treatment option for the management of small inferior calyceal stones with similar efficacy and a better safety profile as compared to standard-PCNL.
Patients/ Guardians/ Participants consent
Patients informed consent was obtained.
Ethical clearance
Institute/hospital ethical clearance certificate was obtained.
Source of support
This paper is based on Armed Forces Medical Research Committee Project No. 5114/2018 granted and funded by the office of the Directorate General Armed Forces Medical Services and Defence Research Developement Organization, Government of India.
Disclosure of competing interest
The authors have none to declare.
Acknowledgement
None.
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