Background
Percutaneous nephrolithotomy (PCNL) currently remains the first-line treatment for large or complex renal stones. Although it is a minimally invasive procedure with higher stone-free rate (SFR), there are still serious complications [
1], such as bleeding and postoperative sepsis. Size of the stone was directly correlating with the overall incidence of complications after PCNL [
2]. Therefore, treatment of large renal stones is still a challenging problem in urology.
The ideal procedure for large or complex renal stones would be the one that achieve complete stone free status with minimal morbidity and with the least number of procedures. The traditional standard procedure was open nephrolithotomy, which evolved into PCNL or retrograde intrarenal surgery [
3]. With the recent development of technique in laparoscopic surgery, laparoscopic pyelolithotomy (LPL) has been frequently considered as an alternative procedure in the management of large or complex renal stones to PCNL or open surgery [
4]. There are some advantages to LPL, the first and most obvious advantage is that most of the stones can be removed integrally, in the next place, including the ability to minimize bleeding, lessen pain, and lower morbidity. Despite the potential advantages, its rare usage.
One prior meta-analysis [
4] evaluated the efficacy and safety of LPL and PCNL in treating large renal stones and found that PCNL and LPL were effective and safe for managing this condition, but also found that LPL seems to be more advantageous. Recently, several additional clinical trials have been reported that compared PCNL and LPL for removal of large renal stones. Therefore, we perform an update meta-analysis to compare LPL and PCNL in terms of efficacy and safety for the management of large renal pelvic stones.
Discussion
One previous meta-analysis [
4] included seven studies with 176 patients underwent LPL and 187 PCNL, showed equivalency for conversion rate, blood transfusion, prolonged urine leakage, and found higher SFR and lower incidence of bleeding and postoperative fever in the LPL group than PCNL group. In addition, the results of the previous study showed that operative time and length of hospital stay were shorter in the PCNL group, drop in hemoglobin level was fewer in the LPL group. In present study, we included 14 studies involving 432 patients underwent LPL and 469 PCNL, and found similar results from the previous meta-analysis regarding SFR, conversion rate, operative time, length of hospital stay, hemoglobin decrease, and postoperative fever. However, in term of blood transfusion rate, we found that there was a significantly lower blood transfusion rate in the LPL group than in the PCNL group, which was different to the previous meta-analysis result. We also found that LPL provided a significantly lower auxiliary procedures and re-treatment rate. The main reason for this difference might be due to the different sample sizes between previous and present studies, which also was the reason of our performed the present study.
Although the SFR was assessed in a different way in each study, the result revealed LPL provided a statistically higher SFR at 3 months after treatment than PCNL, regardless of the definition. The reason may be that most of the stones can be removed integrally in LPL. In the PCNL group, disintegration of the stone may have left some residual stones which can form nuclei for stone recurrence, and the scattering of stone fragments may reduce success rates, which associated with a significantly higher auxiliary procedures and re-treatment rate than LPL. Currently, PCNL is the recommended treatment option for patients with staghorn calculi. However, SFR after PCNL for staghorn calculi only ranges between 49 and 78% [
22]. It is noteworthy that LPL can be considered an alternative and feasible technique to PCNL for patients with complex and large renal stones. Gandhi et al. [
23] reported the 49 patients with staghorn stones (>3–4 cm) underwent LPL, the mean SFR in one session was 90% with lower complications, no blood transfusion and only two patients had urine leak (Clavien-Dindo grade IIIa). However, the leak stopped after 10 days in both patients.
Our results showed that operative time was significantly shorter for PCNL than LPL. As known to all, the operative time is directly related with many variables such as the types of approach, surgeon’s experience, individual differences of patients, and the different equipment used. In LPL procedure, closure of the pyelotomy incision requires advanced laparoscopic skills. Sometimes, delicate renal pelvis tissues, always caused by long-term chronic inflammation, brings many challenges for the closure of the pyelotomy incision [
17] and prolongs the operative time. The longer time of LPL was usually related to the long learning curve as well as the time needed for intracorporeal suturing and delivery of the stone into the endobag [
8]. However, Li et al. [
18] randomized 178 patients with large renal pelvis stones into two groups found the mean operative time was significantly shorter in the LPL than PCNL, which is likely due to stones in LPL can be removed integrally. Indeed, retrieve stones is one of the major limitations of LPL. Lee et al. [
19] used a flexible nephroscope to overcome this difficulty which enable easier approach. With the development of robot technology in urology, this interface maybe will improve the limits of tissue dissection, stone extraction during laparoscopy, intracorporeal reconstruction, and suturing, thereby having the potential to improve the outcomes and flattening the learning curve. However, much less is known about the relative outcomes and costs in robot-assisted pyelolithotomy, which is a major consideration in robotic surgery.
Although LPL have a longer operation time, this may be compensated by the lower complication and higher SFR. Postoperative fever secondary to an urinary tract infection (UTI) in patients with PCNL ranges between 2.8 and 32.1% [
1]. Kidney stones are foreign bodies of the urinary tract and can allow bacteria to grow onto them and then become a reservoir for bacteria. They are disintegrated, bacteria are released from the stone into the collecting system, which tends to result in bacteriuria, bacteremia, and clinical UTI. Recently study demonstrated residual stone is a major contributing factor for the development of fever after tubeless PCNL [
24]. This finding may translate into a clinical benefit for the patients in that stones removed integrally or the higher SFR of the LPL was associated to lower incidence of postoperative fever. Septic shock, the incidence after PCNL was 2.4% [
25], is one of the most dangerous complications after lithotomy due to it can lead to significant mortality. The risk factors for septic shock includes positive urine culture, female gender, renal insufficiency, diabetes mellitus, high pressure of irrigation fluid during PCNL, staghorn calculus, infected stones, indwelling catheters, obstruction, and duration of the operation (> 90 min) [
25,
26]. Positively, strict control of blood glucose and pre-operation antibiotics used could reduce the possibility of post-PCNL septic shock. Early recognition and timely comprehensive treatment of septic shock may decrease the mortality. In addition, infective or septic complications may be associated with laparoscopic approach. Transperitoneal approach could be more at risk about it due to this approach might lead to increase the interference of the abdominal organs, postoperative intra-abdominal infection, and the possibility of adhesions. Further prospective randomized controlled trials are needed to determine which approach should be favored.
Although LPL appears to be more invasive because three or four trocar punctures are needed compared with PCNL in which only a single percutaneous access was made, PCNL make renal parenchymal more susceptible to injury with it tends to result in various complications, such as nephron damage and bleeding. Bleeding after PCNL is common, which leads to a more frequent use of blood transfusion, according to previous reports, 1–12% of patients require [
1]. With increasing stone burden, patients with PCNL, not only SFR decreased, but also the risk of blood transfusion increased [
2]. Risk factors for severe bleeding were upper pole access, solitary kidney, staghorn stone, multiple punctures and inexperienced surgeon [
27]. Therefore, PCNL should be performed by an experienced surgeon in patients at risk for severe bleeding. On the other hand, these patients might as well choose other alternative procedures. Our study found that LPL provided a significantly lower blood transfusion rate, lower bleeding rate, and fewer hemoglobin decrease. The reason was probably due to the fact that LPL harmlessness for renal parenchyma. Whatever the approaches, patients with bleeding tendencies needs careful preoperative, intra- and post-operative management because both the procedures may lead to a kidney loss.
For conversion rate and prolonged urine leakage, regardless of our or previous meta-analyses, the results were similar between the two groups. However, more incidence of prolonged urine leakage and longer hospital stay were found in the LPL group. Urine leakage can be attributed to incomplete closure of the pyelotomy incision after LPL, which can prolong hospital stay [
8]. Closure of pyelotomy incision is technically difficult during laparoscopic surgery, advanced experience and high skills or robot-assisted surgery are needed. But urinary leakage has been minimized with advances in intracorporeal suturing techniques, such as barbed suture [
28]. In addition, suture time was significantly decreased with barbed suture use during laparoscopic pyeloplasty [
29], hence, this will shorten operative time.
However, the complications can be minimized with proper patient selection and sufficient preoperative preparation. LPL is certainly safe and feasible in experienced hands, but should not replace PCNL, which remains the gold standard for kidney stones greater than 2 cm. These procedures are technically challenging and should only be performed by experienced laparoscopic surgeons. According previous studies, LPL is more suitable for patients with urinary deformity require concomitant pyeloplasty.. Patients with previous history of open renal surgery always have significant perinephric adhesion which may affect the success or complication rate in LPL, does not in PCNL [
30]. Therefore, PCNL is the first-selected treatment in such situation. LPL cannot be a feasible modality for renal stones with intrarenal pelvis, which increased the incidence of prolonged urine leakage. All in all, LPL is considered a successful alternative therapy for PCNL in selected cases with large renal stones like those in the extrarenal pelvis in patients without a history of previous surgery. In addition, LPL can be considered as a reasonable therapeutic option for large staghorn calculus which cannot be removed with a reasonable number of access and sessions of PCNL.
This study has some limitations. First, the present analysis was conducted using the currently available comparative studies. However, most of the studies were CCS, had a small sample number and quality ranged from low to moderate. Second, heterogeneity among studies was found to be high for several parameters. This heterogeneity can be explained by the difference in surgical practices, patient inclusion criteria, surgeons’ experience, outcome definitions and standards. Third, the analysis did not incorporate stone shape and composition into the assessment, and either of these could have introduced bias into the analysis. Because of the above limitations might influence the interpretation of our findings, it highlights that large scale, multicenter RCTs are needed for a further robust conclusion.