Ureteroscopic Management with Laser Lithotripsy of Renal Pelvic Stones

Abstract

Background and Purpose:

The development of semirigid and flexible ureteroscopes has permitted easier access to calculi throughout the urinary tract. We compared the use of semirigid and flexible ureteroscopy for the management of shockwave lithotripsy-refractory, isolated renal pelvic calculi by evaluating stone-free rates, operating room times, and associated complications.

Patients and Methods:

Ureteroscopic stone treatment was attempted in 47 patients with isolated renal pelvic stones between November 2008 and December 2010. The procedures were performed under general anesthesia. Semirigid ureteroscopy was routinely performed in all patients. If the stones were accessible in the renal pelvis with the semirigid ureteroscope (S-URS), they were then treated with the holmium:yttrium-aluminum-garnet (Ho:YAG) laser through S-URS under direct vision. If the stones were not accessible, flexible ureteroscopy was then performed. Preoperative, operative, and postoperative data were retrospectively analyzed.

Results:

In 25 of 47 patients, renal pelvic stones were accessible with S-URS, and the stones were fragmented with the Ho:YAG laser using S-URS. In the remaining 22 patients, the stones were accessed with the flexible ureteroscope (F-URS), and the fragmentation of stones was performed with the Ho:YAG laser using the F-URS. There were no significant differences in age, body mass index, grade of hydronephrosis, mean stone size, and stone laterality among the two groups. The mean operative times were 71.90±17.90 minutes in the S-URS group and 93.41±18.56 minutes in the F-URS group (P=0.001). The stone-free rates at postoperative day 1 and at the 1 month follow-up were 72% and 76% in the S-URS group and 81.8% and 86.4% in the F-URS group, respectively (P=0.861 and P=0.368). We found no significant differences among groups with regard to stone-free rates, complication rates, and hospital lengths of stay.

Conclusions:

Although it is well known that flexible ureteroscopy permits a detailed caliceal examination and therapeutic interventions, semirigid ureteroscopy is also often another sufficient means of reaching the renal pelvis in selected patients.

Introduction

V arious treatment options are available for renal calculi, including extracorporeal shockwave lithotripsy (SWL), percutaneous nephrostolithotomy (PCNL) and retrograde intrarenal surgery. The European Association of Urology guidelines on the management of kidney stones in the renal pelvis or upper/middle calix recommends PCNL as first-line treatment for calculi that are more than 2 cm and SWL for calculi that are less than 2 cm.¹

In recent years, the development of small caliber ureteroscopes has allowed for the access and visualization of the renal pelvis, and advances in intracorporeal lithotripsy have permitted the management of calculi along the entire course of the upper urinary tract endoscopically. Ureteroscopy has improved the successful treatment of renal calculi and offers an alternative in the treatment of these stones.^2,3

Although it is well known that flexible ureteroscopy permits a detailed caliceal examination and therapeutic interventions, semirigid ureteroscopy is also often sufficient for reaching the renal pelvis in some patients. We compared the results of semirigid and flexible ureteroscopy for the treatment of renal pelvic calculi by evaluating stone-free rates, operating room times, and associated complications.

Patients and Methods

A retrospective review of 47 patients who were treated at our institution for SWL-refractory renal pelvic calculi from November 2008 to December 2010 was conducted. The patients were evaluated with imaging studies including plain abdominal radiography, intravenous urography, and abdominal ultrasonography to detect the size and location of the stones and the degree of hydronephrosis. The stone size was assessed by measuring its largest dimension using plain abdominal radiography. The urinalysis, urine cultures, and sensitivity testing were conducted, and the appropriate antibiotics were administered preoperatively. The procedures were performed under general anesthesia in all patients. Patients with abnormal anatomy, such as horseshoe, pelvic, and malrotated kidneys, were excluded from the study. All procedures were performed by the same surgeon.

Semirigid ureteroscopy was routinely performed in all patients for the dilation of the ureter and to place a hydrophilic guidewire to the renal pelvis using an 8.5/11.5F, 42.5-cm–long, semirigid ureteroscope (S-URS) with a 6F working channel (Wolf, Knittlingen, Germany). Ureteral balloon dilation was performed when necessary. If the stones were accessible in the renal pelvis with semirigid ureteroscopy, they were fragmented with the holmium-yttrium-aluminum-garnet (Ho:YAG) laser using semirigid ureteroscopy under direct vision. If the stones were not accessible, a second 0.035/0.038-inch safety guidewire was placed into the renal pelvis through the S-URS. After removing the S-URS, a ureteral access sheath (9.5/11.5F or 12/14F) was placed to allow for optimal visualization, to maintain low intrarenal pressure, and to facilitate the extraction of stone fragments. Flexible ureteroscopy was performed using a 7. F, 67.5-cm–long, flexible ureteroscope (F-URS) with a 3.6F working channel (Karl Storz, Tutlingen, Germany).

For lithotripsy, the Ho:YAG laser using a 273 μ laser fiber was used in all cases. The energy and frequency settings were 0.6 to 1.0 J and 5 to 10 Hz (3–10 W), respectively. The stones were fragmented until they were deemed small enough to pass spontaneously. After lithotripsy, a 4.8F Double-J stent was routinely inserted in all patients and removed 14 days after the procedure.

Postoperative plain radiography was used to assess complete stone clearance, and renal ultrasonography was conducted to rule out obstructions or clinically significant renal fragments (>2 mm). One month later, patients were evaluated with repeated renal ultrasonography and intravenous urography to exclude residual stone fragments and ureteral strictures. If a stone recurrence was diagnosed, CT was conducted; it was performed in 11 (23%) patients. All procedures performed in both groups were statistically compared with regard to patient age, sex, body mass index (BMI), grade of hydronephrosis, stone size, lateralization, stone clearance rates, lengths of hospital stays, operative times, and complication rates.

The statistical analyses were performed using the Statistical Package for the Social Science (SPSS 19.0). The normality in the distribution of the data for each variable was explored using the Kolmogorov-Smirnov test. For variables with a normal distribution, the data are expressed as mean±standard deviation. The differences between the two groups were analyzed with independent-samples t tests. The categorical variables are presented as frequencies and percentages, and they were compared using the chi-square test or Fisher exact probability test. Statistical significance was considered at the P≤0.05 level.

Results

In 25 of 47 (53%) patients, the renal pelvic stones were accessible using semirigid ureteroscopy and treated with laser lithotripsy through S-URS. In the remaining 22 (47%) patients, the renal pelvic stones were not available using semirigid ureteroscopy, and they were managed with laser lithotripsy using F-URS. Semirigid ureteroscopy was successful in reaching renal pelvic stones in 16 of 26 (61.5%) female patients; however, stones were accessible only in 9 (42.8%) of 21 male patients (P=0.161).

The preoperative characteristics of the patients are summarized in Table 1. The mean stone size was 15.10±5.70 mm in the S-URS group and 13.32±5.50 mm in the F-URS group (P=0.278). All stones in both groups were less than 20 mm in diameter. There was no significant difference between the groups regarding patient sex, age, BMI, grade of hydronephrosis, mean stone sizes, and lateralization rates (Table 1).

Table 1.

Patıent and Stone Characterıstıcs of Groups

Variables	Group 1 (n=25) (Semirigid URS)	Group 2 (n=22) (Flexible URS)	P value
Age (y)	42.80±11.50	46.05±12.02	0.343
BMI	25.30±3.90	23.64±3.72	0.150
Sex			0.428
Male	9 (36%)	12 (54.5%)
Female	16 (64%)	10 (45.5%)
Mean stone size (mm)	15.10±5.70	13.32±5.50	0.278
Hydronephrosis			0.993
Grade 1	11 (44%)	9 (40.9%)
Grade 2	7 (28%)	6 (27.3%)
Grade 3	4 (16%)	4 (18.2%)
Grade 4	3 (12%)	3 (13.6%)
Laterality			0.820
Left	13 (52%)	12 (54.5%)
Right	12 (48%)	10 (45.5%)

URS=ureteroscopy; BMI=body mass index.

The mean operative times were 71.90±17.90 minutes in the S-URS group and 93.41±1 8.56 minutes in the F-URS group (P=0.001). The stone clearance rates at postoperative day 1 and 1 month after the procedure were 72% and 76% in the S-URS group and 81.8% and 86.4% in the F-URS group, respectively (P=0.861 and P=0.368). The mean hospitalization times were 1.5±1.2 days in the S-URS group and 1.5±1.3 days in the F-URS group (P=0.904). We found no significant differences between groups with regard to stone clearance rates and hospital lengths of stay (Table 2).

Table 2.

Operatıve and Postoperatıve Outcomes of Groups

Variables	Group 1 (semirigid URS)	Group 2 (flexible URS)	P value
Mean operative time (min)	71.90±17.90	93.41±18.56	0.001
Stone clearance rate
Postoperative first day	18 (72%)	18 (81.8%)	0.861
Postoperative first month	19 (76%)	19 (86.4%)	0.368
Complication rate	4 (16%)	3 (13.6%)	0.202
Mean hospitalization time (d)	1.5±1.2	1.5±1.3	0.904

The degree of hydronephrosis detected by ultrasonography did not affect stone-free rates in both groups (P=0.29 for the S-URS group, P=0.22 for the F-URS group).

There were no intraoperative complications in either group. At postoperative day 1, four patients in the S-URS group and two patients in the F-URS group had fever and were treated with antibiotics. One patient in the F-URS group experienced bleeding needing no transfusion. The complication rates were similar in both groups.

Ureteral balloon dilation was needed in 8 (17%) patients. In the evaluation with intravenous urography at 1 month after the procedure, there was no evidence of ureteral stricture in any patient.

Discussion

Although guidelines on the management of renal calculi recommend PCNL as the first-line treatment for intrarenal calculi>2 cm and SWL for renal calculi<2 cm, the retrograde intrarenal surgery is becoming a widely used treatment method for upper urinary tract lithiasis.^1,4 Despite the high success rates exceeding 90% that are reported with PCNL, the major complications during or after PCNL occur at the reported rates of 0.03% to 10%.⁵ The following rates of complications have been reported in PCNL procedures: Clavien II complications, including blood transfusion and parenteral nutrition, in 7%; Clavien III complications necessitating intervention in 4.1%; Clavien IV (life-threatening) complications in 0.6%; and Clavien V (mortality) in 0.04%.⁶

Improvements in the new generation of flexible ureteroscopes have made retrograde endoscopic ureteroscopy and laser lithotripsy for renal calculi more popular. The overall success rates of retrograde intrarenal surgery have been reported as 75% to 95% for intrarenal stones>2 cm after the first or second treatment, whereas the major and minor complication rates vary from 1.5% to 12%, which are less frequent than rates in PCNL procedures.³ The major complications, such as ureteral avulsion or perforation, are exceedingly rare in modern series.

The major disadvantage of flexible ureteroscopes is that these instruments are less durable than rigid ureteroscopes and S-URS.⁷ In addition, Sung and associates⁸ demonstrated that the cost of repair is greater for F-URS than for S-URS. It has been reported that the durability of F-URS is affected by the number of surgical procedures, the complexity of the procedure, the experience of the endoscopist, the method of sterilization, and the ancillary personnel tending to the instrument after its use.⁷ In a recent study, to minimize the total F-URS time, Ebert and colleagues⁹ determined a new technique to treat renal calculi ureteroscopically. In this technique, the renal stones were fragmented with a laser fiber using semirigid instruments, after the reposition of the renal calculi to the renal pelvis with flexible instruments. The authors discussed that the access- or exposition-related problems can be solved and the repair costs of the instruments will be minimized with this technique.

In the literature, there are few reported studies on the use of semirigid ureteroscopy to treat renal stones. Bryniarski and coworkers¹⁰ prospectively analyzed the safety and efficacy of PCNL and retrograde intrarenal surgery using semirigid ureteroscopy in the management of renal stones of>2 cm in diameter. The authors reported that, although stone-free rates were superior in the PCNL group, retrograde intrarenal surgery with semirigid ureteroscopy offers advantages for operating times, hemoglobin and hematocrit reductions, postoperative visual analog score points, the need for pain treatment, and the duration of hospital stay.

In most of the published articles, retrograde intrarenal surgery using the F-URS begins with the entry of the cystoscope into the bladder and the placement of a retrograde guidewire up to the kidney.^3,11,12 In this procedure, a second guidewire is placed up to the kidney level using a dual lumen catheter. According to the surgeon's preference, the F-URS is threaded into the renal pelvis over the working wire or through a ureteral access sheath. In our technique, semirigid ureteroscopy was routinely performed in all patients for the dilation of the ureter and to place a hydrophilic guidewire to the renal pelvis. If the stones were accessible in the renal pelvis with semirigid ureteroscopy, they were treated through semirigid ureteroscopy using a Ho:YAG laser under direct vision. If the stones were not accessible, flexible ureteroscopy was performed. With this technique, the number of procedures to treat renal calculi were decreased, given our use of F-URS. In addition, when we compared the two groups, the operative time was lower in the S-URS group, compared with the F-URS group, whereas the stone-free rates, complication rates, and lengths of hospital stays were similar in both groups.

In this present study, we achieved a 53% success rate at reaching renal pelvic stones. In 47% of patients, it was not possible to reach the renal pelvis because of a narrow ureter, shortness of the S-URS, kinking at the ureteropelvic junction, and inability to pass over the iliac vessels. In a recent study, Dagnone and colleagues¹³ reported that lower-abdominal pressure can be helpful to negotiate passage of the S-URS over the iliac vessels or to place the laser fiber on stones. In our study group, we did not try any maneuvers to facilitate access to the renal pelvis. Most of the patients (64%), however, were women in whom we reached their renal pelvic stones. Although there was no statistically difference between sex and success of S-URS, it was easier to reach the renal pelvis in females than males. It has been reported that female patients usually have less fixed ureters with a lower degree of curvature over the iliac bifurcation and the male urethra requires a greater degree of torque to negotiate it, so easier maneuverability is necessary for reaching the renal pelvis at women.¹⁴

The major disadvantage of the S-URS is that this instrument has a limited maneuvering capacity during stone fragmentation, and the fragments that fall into the other calixes, especially into the lower calix, cannot be reached with this instrument.¹⁰ This disadvantage may result in lower stone-free rates when treating renal and ureteral calculi with semirigid ureterosocopy, when compared with flexible ureteroscopy. In our study group, during semirigid stone disintegration, some particles displaced into the caliceal cavities in seven (25%) patients, and they were left for spontaneous passage; however, there were still six (24%) patients left with residual stones at the first month after the procedure. Although the stone-free rates at postoperative day 1 and at 1 month follow-up were lower in the S-URS group, the differences were not statistically significant. Similarly, it has been reported that the results with URS using a F-URS for proximal ureteral stones appear to be better than those achieved with a rigid device (87% vs 77%), but not to a significant degree.¹⁵

In both of the ureteroscopic procedures, the renal pelvic pressure increases through irrigation, and this can lead to intrarenal, pyelovenous, and pyelolymphatic backflow that may result in infectious complications.¹⁶ While performing flexible ureteroscopy, the pelvic pressure can be lowered by using a ureteral access sheath, irrigating with isoproterenol, and limiting the operative time.^17,18 In our study groups, to maintain low pelvic pressure, we placed the ureteral access sheath during flexible ureteroscopy procedures and lowered the irrigation rates while performing semirigid ureteroscopy. There were four patients in the S-URS group and two patients in the F-URS group who had postoperative fever, and they were successfully treated with antibiotics. We did not observe any septic complications after the procedures.

The routine placement of ureteral stents after uncomplicated ureteroscopy is controversial. It has been suggested that multiple variables—including a longer operative time (especially>45 minutes), repeated access, management of a large stone, impacted calculi with ureteral wall edema, a mildly narrowed ureteral segment, ignored caliceal small calculi, and a recent history of urinary tract infection—are associated with the development of postoperative complications in patients without stents.¹⁹ Although we did not observe any intraoperative complications in either group, we placed a ureteral Double-J stent in all cases because of the longer operative time.

Ureteral strictures after ureteroscopic procedures have been reported in 3% to 5% of patients.^20,21 This complication is rare in modern series, because the instrument size has decreased. In this study, only eight (17%) patients needed a ureteral balloon dilation. Double-J stents were placed in all patients and removed at 2weeks postoperatively. In the evaluations with intravenous urography at 1 month after surgery, no evidence of ureteral stricture was observed in any patient.

The main aim of this present study is not to compare the results of semirigid and flexible ureteroscopy for renal pelvic calculi, and not to advise semirigid ureteroscopy as a first option in the management of that stones, but rather to show that semirigid ureteroscopy could be used to manage renal pelvic calculi in some cases. The aim was, therefore, to determine whether the requirement of flexible ureteroscopy application can be decreased and whether the need for repair of the instruments can be minimized. Furthermore, we suppose that if fragments falls into other calices during semirigid ureteroscopy, flexible ureteroscopy could be used to remove or treat those fragments and as a result, the total flexible ureteroscopy time could be decreased.

Our study has several limitations. This is a retrospective analysis of patients with SWL-refractory renal pelvic stones from a single institution who were treated ureteroscopically. Another limitation of our study is that we did not include a cost analysis of the techniques. Consequently, we could not objectively evaluate the disparity in the cost of the techniques. We performed renal ultrasonography and intravenous urography to exclude residual stone fragments at follow-up, and a CT scan was not routinely performed in all patients, to avoid radiation exposure. Ultrasonography and intravenous urography, however, may miss some of the residual stones, and this is another limitation of our study.

Conclusions

Although it is well known that flexible ureteroscopy enables a detailed caliceal examination and facilitates therapeutic interventions, semirigid ureteroscopy is also often sufficient for accessing the renal pelvis and providing safe laser fragmentation in selected patients. These measures result in decreased operative times, similar stone-free rates, and similar complication rates, compared with flexible ureteroscopy. Furthermore, the use and need for the repair of flexible instruments will be minimized.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

References

Türk

, Knoll

, Petrik

et al. Guidelines on Urolithiasis. 2010, 1–106. http://www.uroweb/gls/pdf/Urolithiasis%202010.pdf. 2012 March 2.

Traxer

, Dubosq

, Jamali

et al. New-generation flexible ureterorenoscopes are more durable than previous ones. Urology, 2006; 68:276–281.

Breda

, Ogunyemi

, Leppert

et al.

Flexible ureteroscopy and laser lithotripsy for single intrarenal stones 2 cm or greater—is this the new frontier?

J Urol, 2008; 179:981–984.

Preminger

, Assimos

, Lingeman

et al. Chapter 1: AUA Guideline on management of staghorn calculi: Diagnosis and treatment recomendations. J Urol, 2005; 173:1991–2000.

Michel

, Trojan

, Rassweiler

. Complications in percutaneous nephrolithotomy. Eur Urol, 2007; 51:899–906.

Seitz

, Desai

, Häcker

et al. Incidence, prevention, and management of complications following percutaneous nephrolitholapaxy. Eur Urol, 2012; 61:146–158.

Basillote

, Lee

, Eichel

et al. Ureteroscopes: Flexible, rigid, and semirigid. Urol Clin N Am, 2004; 31:21–32.

Sung

, Springhart

, Marguet

et al. Location and etiology of flexible and semirigid ureteroscope damage. Urology, 2005; 66:958–963.

Ebert

, Schafhauser

. [Combined flexible and semirigid ureteroscopy with laser lithotripsy. Alternative to percutaneous nephrolithotomy of complex ESWL refractory nephrolithiasis.] (Ger) Urologe A, 2008; 47:994–999.

10.

Bryniarski

, Paradysz

, Zyczkowski

et al. A randomized controlled study to analyze the safety and efficacy of percutaneous nephrolithotripsy and retrograde intrarenal surgery in the management of renal stones more than 2 cm in diameter. J Endourol, 2012; 26:52–57.

11.

Hyams

, Shah

. Percutaneous nephrostolithotomy versus flexible ureteroscopy/holmium laser lithotripsy: Cost and outcome analysis. J Urol, 2009; 182:1012–1017.

12.

Chung

, Aron

, Hegarty

, Desai

. Ureteroscopic versus percutaneous treatment for medium-size (1-2–cm) renal calculi. J Endourol, 2008; 22:343–346.

13.

Dagnone

, Blew

, Pace

, Honey

. Semirigid ureteroscopy of the proximal ureter can be aided by external lower-abdominal pressure. J Endourol, 2005; 19:342–347.

14.

Khairy-Salem

, el-Ghoneimy

, el-Atrebi

. Semirigid ureteroscopy in management of large proximal ureteral calculi: Is there still a role in developing countries? Urology, 2011; 77:1064–1068.

15.

Preminger

, Tiselius

, Assimos

et al. 2007 guideline for the management of ureteral calculi. J Urol, 2007; 178:2418–2434.

16.

Binbay

, Yuruk

, Akman

et al.

Is there a difference in outcomes between digital and fiberoptic flexible ureterorenoscopy procedures?

J Endourol, 2010; 24:1929–1934.

17.

Jung

, Norby

, Frimodt-Moller

, Osther

. Endoluminal isoproterenol irrigation decreases renal pelvic pressure during flexible ureterorenoscopy: A clinical randomized, controlled study. Eur Urol, 2008; 54:1404–1413.

18.

Auge

, Pietrow

, Lallas

et al. Ureteral access sheath provides protection against elevated renal pressures during routine flexible ureteroscopic stone manipulation. J Endourol, 2004; 18:33–36.

19.

Tanriverdi

, Yencilek

, Koyuncu

et al. Emergent stenting after uncomplicated ureteroscopy: Evaluation of 23 patients. Urology, 2011; 77:305–308.

20.

Irwin

, Desai

. Ureteroscopic superiority to extracorporeal shock wave lithotripsy for the treatment of small-to-medium-sized intrarenal non-staghorn calculi. Urology, 2009; 74:256–258.

21.

Jung

, Norby

, Osther

. Retrograde intrarenal stone surgery for extracorporeal shock-wave lithotripsy-resistant kidney stones. Scand J Urol Nephrol, 2006; 40:380–384.