Does Previous Failed Shockwave Lithotripsy Treatment Have an Influence on Retrograde Intrarenal Surgery Outcome?

Introduction

The prevalence of urolithiasis is nearly 20% all over the world and patients with urolithiasis constitute an essential part of the patients referred to the urology clinic. ¹ Many parameters should be considered on the management of renal stones and authors recommend extracorporeal shockwave lithotripsy (SWL), retrograde intrarenal surgery (RIRS), and percutaneous nephrolithotripsy (PNL), as treatment options. ² Among these minimally invasive techniques, SWL does not require general anesthesia, has 89% success rate for renal pelvic stones: 83% for upper caliceal stones, 84% for middle caliceal stones, and 68% for lower caliceal stones. ³ New endoscopic equipment and laser devices with powerful and functional optics that are used in combination with advances in technology have revolutionized the treatment of kidney stones and have made the RIRS method popular, safe, and efficient, which is previously used as salvage therapy in SWL resistant stones. In this study, we aimed to investigate whether the previously failed SWL treatment affects RIRS outcome.

Materials and Methods

Patients who underwent RIRS for kidney stones between January 2012 and December 2017 in Diskapi Yildirim Beyazit Training and Research Hospital were reviewed retrospectively; demographic data of the patients, number of stones, and localization were recorded. Patients treated with primary RIRS (186 patients) were classified as Group 1. The outcomes of these patients were compared with those of 186 patients who underwent RIRS after failed SWL treatment using matched-pair analysis, and these patients were classified as Group 2. The matching parameters were gender, age, and body mass index of the patients, as well as the size and number and location of the stones.

Complete blood count, urinalysis, urine culture, coagulation, and kidney function tests of the patients referred to the urology clinic for flank pain and hematuria were analyzed. All of the patients were evaluated using ultrasonography (US), intravenous urography, and computed tomography (CT) preoperatively. The patients who had urinary infection were treated with appropriate antibiotics and underwent surgery after sterile urine cultures were collected. Intervention for the kidney stones as SWL or RIRS was planned by the expectation and preference of both the patient and the surgeon.

Informed consent was obtained from the patients decided for SWL treatment and maximum three SWL sessions at 2-week intervals were applied by electrohydraulic extracorporeal lithotriptor (Multimed Classic; Elmed, Ankara, Turkey). All patients were checked using X-ray or US for stone clearance the next week, and cases with intact stones despite SWL treatment were decided as failure and managed with RIRS.

Also, informed consent was obtained from every patient who decided to undergo surgery. All of the urine culture samples were sterile before the surgery. Under general anesthesia and fluoroscopic control, the guidewire was placed on the renal pelvis. Diagnostic ureterorenoscopy was performed; the whole ureter was observed through up to the ureteropelvic junction and the ureter was dilated using the semirigid ureteroscope.

An access sheath (9.5/11.5F or 11/13F) (Elit Flex, Ankara, Turkey) was pushed forward up to the ureteropelvic junction through the guidewire, then the renal pelvis and collector system were observed using the flexible ureteroscope (Flex-X2, Karl Storz, Tuttlingen, Germany/Karl Storz, Flex X2, GmbH, Tuttlingen, Germany). After reaching the stone, the stone was dusted or fragmented using a 200 μm holmium laser probe (Ho YAG Laser; Dornier MedTech; Munich, Germany/Dornier Med-Tech GmbH, Medilas H20 and HSolvo, Wessling, Germany) at 8–10 Hz and 1.0–1.8 J.

Afterward, the whole collecting system was observed again and searched for fragments. Finally, a 4.8F Double J (DJ) ureteral stent was placed to the renal pelvis. All of the patients were checked using X-ray on the postoperative first day and using CT on the third month for stone clearance. The procedure was considered successful for patients when the stone was completely fragmented or residual stones remained clinically insignificant at ≤2 mm. Procedures with residual stones ≥3 mm were considered as failure and these patients were treated with auxiliary procedures (medical therapy, second stage RIRS, or PNL). DJ ureteral stents were displaced on the postoperative 14th day.

Time from insertion of the cystoscope to the placement of DJ ureteral stent was recorded as operation time. Also, fluoroscopy time and perioperative–postoperative complications were recorded.

Results

Demographic data of the patients included in the study were similar and are summarized in Table 1. The mean age of the patients was 47.87 (±13.53) years in Group 1 and 46.18 (±13.19) years in Group 2. No statistically significant difference was found (P = .223).

Location and number of the stones and stone burden were similar between the two groups. Upper caliceal stones were the majority in both groups when the analysis was performed for stone location (34.9% for Group 1; 36% for Group 2). The mean number of stones was 1.20 (±0.45) in Group 1 and 1.30 (±0.81) in Group 2. Stone burden was similar between the two groups and there was no statistically significant difference (P = .994). Stone parameters are summarized in Table 2.

Operation time for both groups was similar; 44.18 (±14.26) minutes for Group 1 and 43.84 (±16.6) minutes for Group 2 (P = .451). However flouroscopy time for two groups differs as 47.58 seconds for Group 1 and 35.19 seconds for Group 2 (P < .05).

Hospital stay was 1.03 and 1.05 days, respectively, for both Group 1 and Group 2 and no statistical difference was noticed. Complication rates were similar while there was no major complication in Group 2 but only one collecting system perforation in Group 1.

One hundred sixty-five (88.7%) patients were completely stone-free, 18 patients (9.7%) failed, and 3 (0.8%) patients with clinically insignificant residual fragments (CIRFs) were noticed in Group 1. In Group 2, 158 (84.9%) patients were stone-free, 15 (8.1%) patients failed, and CIRFs were noticed in 13 (3.5%) patients. It was found that there was a statistically significant difference between the two groups regarding total stone-free rates (P = .03).

The procedure success was defined as the patients were stone-free or had CIRF. The procedure success rates were 90.3% and 91.9%, respectively. If we compare the final success rates, there was no statistically significant difference between both groups (P = .584). Operation outcomes are summarized in Table 3.

Discussion

Today, open surgery in kidney stone treatment has lost its importance except for selected cases; many minimally invasive methods such as SWL, PNL, RIRS, miniperc, and microperc have become available on this field and gained popularity. PNL, in particular, large renal stones, appears to be the treatment of choice with the highest success rates, but it is beginning to give way to other methods such as RIRS, which are less invasive because of the morbidity they cause. Current guidelines recommend SWL and endoscopic techniques for kidney stones up to 20 mm as first-line treatment, whereas PNL is recommended as first-line treatment in stones >20 mm. Treatment of lower caliceal stones between 10 and 20 mm is challenging and the surgical method is decided according to the presence or absence of steep infundibular-pelvic angle, long calix, long skin to stone distance, narrow infundibulum, and SWL resistant stones. ²

Obesity, skin to stone distance, density and the localization of the stone in the kidney, and anatomic structure of the kidney affect the SWL success rate. Even though the success rates are 89% in the renal pelvis, 83% in upper calix and 84% in middle calix, lower caliceal stones are affected by these factors and the success rate of SWL alters 44.6%–90%.^3,4 However, RIRS procedure is less affected by these parameters and provides higher success in lower caliceal stones. El-Nahas et al. ⁵ reported that the RIRS procedure was more successful than SWL in their studies when comparing SWL and RIRS in lower caliceal stones between 10–20 mm (86.5%–67.7%). This success rate was reported to be as high as 93.7% even for larger kidney stones in other localizations. ⁶

Stav et al. ⁷ reported a 67% final success rate in 81 patients in their study, in which they investigated RIRS success after SWL failure. In another study, Holland et al. ⁸ compared RIRS procedure after previously failed SWL and primary RIRS procedure in 93 patients and reported higher success rate for the primary group (80%–67%). This significant difference is attributed to the fact that the lower pole anatomy affecting SWL success has not been adequately assessed in majority of the patients included in the study. Also, it is explained by the fact that the RIRS success may have been reduced due to stone fragments embedding into the kidney mucosa after SWL.

However, Philippou et al. ⁹ investigated 87 patients in a similar study and reported 78.4% stone-free rate in the primary group and 62.7% in the salvage RIRS group. He stated that there is no statistical difference between success rates among the two groups. ⁹ Also, Yürük et al. ¹⁰ reported 82.5% and 86.9% success rates for primary and salvage RIRS patients, respectively; both success rates were similar. ¹⁰ In our study, we did not notice any significant difference between groups for success rates as newly reported in the literature (P = .584).

However, when the CIRFs were considered as an independent factor, a significant difference was found in the fact that stone-free rates were achieved between the two groups (P = .03). CIRF was mostly researched in SWL and PNL procedures; when a cutoff value of 2 mm is accepted as CIRF, the less stone-related event is developed than larger residual fragments. ¹¹ For the RIRS procedure, most of the clinical insignificant residual fragments pass spontaneously or stay silent in the renal collecting system. In long-term follow-up, one-third of these patients become symptomatic in 30 months period, thus a strict follow-up procedure should be kept in mind. ¹²

The operation and fluoroscopy time may vary depending on the localization of the stone, the size of the stone, the complexity of the case, and the experience of the surgeon. Deters and Pais, ¹³ have investigated the effect of the stone location on the operation time. They have performed RIRS to 98 patients with renal stones and reported 112.1 minutes for the operation time. This time was significantly higher than the operation time of 115 patients who had ureteral stones. Sorokin et al. ¹⁴ reported an average of 50.1 minutes duration of operation with 118 patients and stated that the most influential factor was the stone size. They estimated that an average of 2 minutes were required for 100 mm ³ stone volume to predict how long the operation will last. ¹⁴ Weld et al. ¹⁵ reported an average of 69.1 seconds of fluoroscopy time in their study, and they noted the experience of the surgeon and the use of fluoroscopy while placing the stent were the influencing factors. In our study, the mean fluoroscopy time was 47.58 seconds in Group 2 and 35.19 seconds in Group 1. When we compare both groups, there was a statistically significant difference (P = .022). In this study, there was no data to present the density of the stone. But we think that the fluoroscopy time is higher in the patients who received SWL treatment before because the hard stones had been fragmented instead of dusting.

Renal colic, urinary obstruction, and macroscopic hematuria are the most common complications after SWL. Salem et al. ¹⁶ performed a large study of 4241 patients who underwent SWL and reported that complications were mostly low grade. Serious complications such as sepsis (0.06%), acute tubular necrosis (0.03%), and mortality (0.06%) are rarely seen after SWL. ¹⁶ Complications similar to SWL can also be observed in the RIRS procedure, but because of the minimally invasive nature, these complications are usually low-grade complications such as postoperative fever, hematuria, and renal colic. ¹⁷ In our study, total complication rate was 8.3%. In Group 1, 8.6% and in Group 2, 13.4% of the patients had complications. Most of these complications were minor complications such as fever and nonsepsis-induced infections, but only in 1 patient in Group 1, collecting system perforation occurred. This patient was followed by placing the DJ catheter and no additional intervention was needed.

Equipment that develops with minimally invasive methods ensures that RIRS becomes a safe and effective method for outpatient surgery. ¹⁸ The low incidence of complications and the fact that these complications are mostly minor also decrease the hospital stay, RIRS becomes an outpatient surgery procedure in some centers. Patients included in the study had a mean hospital stay of 1.03 days for Group 1 and 1.05 days for Group 2.

We would like to state that the limitations of our study are retrospective and nonrandomized nature. Therefore, prospective and randomized studies are needed to clarify whether a failed SWL treatment has a negative effect on RIRS outcome.

Conclusion

There is no negative effect of the previous unsuccessful SWL treatment on the RIRS success. Patients with CIRF should be followed up more carefully in terms of becoming symptomatic. However, these findings must be confirmed by additional prospective studies.