Outcomes and Long-Term Follow-Up with the Use of Ureteral Access Sheath for Pediatric Ureteroscopy and Stone Treatment: Results from a Tertiary Endourology Center

Abstract

Purpose:

The aim of this study was to retrospectively analyze outcomes of flexible ureteroscopy and laser fragmentation (FURSL) of renal stones with the use of ureteral access sheath (UAS) in the pediatric population.

Materials and Methods:

We retrospectively collected data between January 2011 and January 2018 for patient demographics, stone characteristics, and outcomes in 21 children who underwent FURSL with the use of UAS.

Results:

Twenty-one patients (10 boys and 11 girls) with a mean age of 11.8 years (range: 2–16 years) underwent FURSL using an access sheath. The stone location was in the lower pole in 13 patients (62%) with 12 patients (57%) having multiple stones. A 9.5F (35 cm) Cook Flexor UAS was used in all cases. The mean and overall stone size was 12 mm (range: 5–30 mm) and 15.4 mm (range: 5–35 mm), respectively. Preoperative stent was present in 8(38%) patients, and a postoperative stent or overnight ureteric catheter was inserted in 14 patients (67%). Thirty-one procedures (average: 1.5/patient) were needed to achieve a stone-free rate of 95%. There were no procedural or long-term complications noted over a mean follow-up of 26 months (4–37 months).

Conclusion:

The use of UAS in the treatment of pediatric renal stones is safe and feasible with good outcomes and without any long-term sequelae.

Introduction

Urolithiasis in pediatric patients has increased fourfold in the last two decades.^1,2 There has been a paradigm shift in the management of renal tract calculi in the pediatric patients over the last 30 years, shifting from open surgery to ureteroscopy for stone treatment.³ Similarly, flexible ureteroscopy and stone fragmentation (FURSL) seems to have excellent outcomes in not only high but also medium volume centers.⁴

The use of ureteral access sheath (UAS) for FURSL in adult population is published, and outcomes show the safety and efficacy of its use.⁵ The perceived advantages include a low intrarenal pressure, better vision, increased stone clearance, and a decrease in infective complications.⁶ But UAS in the pediatric population is less well described and has been plagued by concerns about potential damage to the ureteric wall, ranging from urothelial abrasion to wall ischemia and ureteric avulsion.^7

–10

We hypothesize that UAS is safe for treatment of pediatric stones without any long-term sequalae. This study aims to investigate the role of UAS for outcomes of FURSL in pediatric patients with large renal stones.

Materials and Methods

Between January 2011 and January 2018, 105 ureteroscopy procedures were performed for pediatric stones (≤16 years of age). Of these, 21 (20%) patients underwent URS with the use of UAS. Data were collected for patient demographics, stone characteristics, and outcomes of all 21 patients who underwent FURSL with the use of UAS.

Our standard FURSL technique has been described previously.^11,12 While small single renal stones were mostly treated without a UAS, larger or multiple stones were treated using a UAS, whenever it was feasible and safe to do so. All patients underwent a cystoscopy-guided safety wire placement followed by a semirigid ureteroscopy to passively dilate the ureter and to estimate on whether a placement of UAS was possible. UAS was only placed in patients where the size of the ureter would allow this to happen, otherwise, a flexible ureteroscope was guided over a working wire.

A routine preoperative assessment was carried out¹¹ with renal tract ultrasound (USS) used for initial diagnosis and follow-up. Patients received antibiotic prophylaxis at induction of general anesthesia (GA). Intrarenal pressure and operative time were kept low to minimize risks of increased intrarenal pressure and urosepsis. Patients were routinely admitted on the day of the procedure and observed overnight and discharged home the next morning.

All ureteroscopy procedures were performed under a GA, using 4.5F (Richard Wolf) semirigid and 7.5F Flex X2 flexible ureteroscopes [Karl Storz Endoscopy (UK) Ltd., Slough, UK] with a Holmium:YAG laser [Versa Pulse Holmium Powersuite 100W; Lumenis (UK) Ltd., Elstree, UK] using a 272-μm laser fiber (Lumenis, Inc.) irrespective of the stone size or location. A 9.5F/11F (35 cm) Cook Flexor UAS was used in some cases. When possible, an attempt was made to remove a stone fragment for stone analysis using a Cook NGage^® nitinol stone extractor (Cook Medical, USA). A 4.7F ureteric stent (Cook Medical) or an overnight ureteral catheter was inserted in some patients to aid clearance of stone fragments. If a ureteric stent was inserted, this was removed 6–8 weeks postoperatively under a GA.

Postoperative renal tract USS was undertaken 6–12 weeks following FURSL, either in our hospital or in the peripheral/parent-referring hospital. Subsequent follow-up imaging in form of USS was done every 3–6 months as per local protocol. Stone-free rate (SFR) was defined using a combination of (1) being endoscopically stone free immediately after FURSL and (2) radiologically stone free (defined as fragments ≤2 mm) on follow-up imaging (USS). Patient demographics, operative details, stone characteristics, hospital stay, complications, and SFR were recorded on an Excel spread sheet (Microsoft, USA) and analyzed.

Results

Patient demographics

Between January 2011 and January 2018, a total of twenty-one patients underwent FURSL using a UAS with a Male:Female ratio of 10:11 and a mean age of 11.8 years (range: 2–16 years). The clinical presentations included renal colic (n = 9), urosepsis (n = 7), hematuria (n = 4), incidental finding (n = 4), and pyelonephritis (n = 1) (Table 1).

Table 1.

Patient Demographics and Overall Outcomes of the Study

Patient demographics and clinical data (N = 21)	n (%) ± SD
Male:Female (n)	10:11
Mean age, years (range)	11.8 (2–16)
Clinical presentation
Renal colic	9
Urosepsis	7
Hematuria	4
Incidental finding	4
Pyelonephritis	1
Stone size (cumulative) in mm	15.4 mm (range: 5–30 mm)
Stone location
Lower pole	13
Renal pelvis	6
Upper calix	5
Middle calix	5
Pelvi-ureteric junction (multiple stones)	1 (12)
Access sheath, n (%) (size: 9.5/11.5)	21 (100)
Preoperative stent, n (%)	8 (38)
Postoperative stent placement, n (%)	14 (67)
Hospital stay	1 day
Complications	NIL
SFR, n (%)	95% (1.5 procedures/patient)
Mean length of follow-up (range)	26 months (range: 4–37 months)

SD = standard deviation.

Stone characteristics

The stone location was most commonly located in the lower pole (n = 13, 62%) followed by the renal pelvis (n = 6), upper pole (n = 5), middle calix (n = 5), and pelviureteric junction (n = 1) with 12 patients (57%) having multiple stones. The mean and overall stone size was 12 mm (range: 5–30 mm) and 15.4 mm (range: 5–35 mm), respectively.

Operative demographics

A 9.5F (35 cm) Cook Flexor UAS was used in all cases. A preoperative stent was present in 8 (38%) patients. Postoperative stent or overnight ureteric catheter was inserted in 14 patients (67%). Thirty-one procedures (mean 1.5/patient) were needed to achieve a SFR of 95%. The stone was of mixed composition in 10/21 patients with various combinations, including calcium oxalate (n = 10) followed by calcium phosphate (n = 6) and magnesium ammonium phosphate (n = 6).

Outcomes

The majority of our patients (95%) were stone free at the time of treatment completion. One patient was not stone free owing to the stone in an inaccessible lower pole. All our patients were discharged from hospital within 24 hours of admission (morning after surgery). There were no procedural, immediate, or long-term complications noted over a mean follow-up of 26 months (4–37 months).

Discussion

Meaning of our study

Our study shows the importance of UAS use for treatment of large pediatric renal stones. More than three-fifths (62%) of patients did not have a preoperative stent in situ. There were no access sheath-related complications. Excellent SFR was achieved with no intra- or postoperative complications with all patients discharged the following day. Over a long-term follow-up of 26 months, no complications in terms of ureteric stricture were noted.

Comparison with other pediatric studies using UAS

It is well established that FURSL for management of pediatric renal calculi is an effective and safe procedure with high success rates (78%–91%)^{13

–22} (Table 2). Availability of small caliber pediatric endoscopes and the widespread use of the holmium:YAG laser make FURSL a viable option for pediatric patients.¹² It is efficacious irrespective of the stone composition or stone location.³ However, complication rates of FURSL range between 0% and 27.7%.³ The most frequently observed complications were urinary tract infection, postoperative hematuria, fever, ureteral mucosal injury, and ureteral perforation or avulsion.¹⁵

Table 2.

Studies with Results of Pediatric Ureteral Access Sheath Use

Study	Total	Mean age (years)	Mean stone size (mm)	UAS use (%)	SFR (%)	Complications (%)	Mean follow-up (months)
Cannon et al.¹⁷	21	15.2 (1–20)	12 ± 5.9	43	76	Nil	11
Smaldone et al.¹⁸	100	13.2 ± 5.4	8.3 ± 5.3	24	91	Ureteral stricture (1)	10.1
Smaldone et al.¹⁸	100	13.2 ± 5.4	8.3 ± 5.3	24	91	Ureteral perforation(5)	10.1
Tanaka et al.¹⁹	50	7.9 (1.2–13)	8 (1–16)	48	58	1	NA
Kim et al.²⁰	167	5.2 (1–18)	6.1 (3–24)	in heavy stone burden cases only	100	Nil	19.7 (6–39)
Yuruk et al.²¹	14	10.9 ± 2.2 (7–15)	13.6 ± 2.4 (10–18)	85.7		Grade 1 ureteral laceration (1)	25.7 ± 5.2
Yuruk et al.²¹	14	10.9 ± 2.2 (7–15)	13.6 ± 2.4 (10–18)	85.7		Postoperative pyrexia (1)	25.7 ± 5.2
Unsal and Resorlu¹³	16	4.2 (0–7)	11.5 (8–17)	17.6	81	Ureteral perforation (1)	10.3
Erkurt et al.²²	65	4.3 (0–7)	14 (7–30)	100	93	27%	NA
Current study	21	11.8 (2–16)	15.4 (5–30)	100	95	Nil	26 (4–37)

NA = not available; SFR = stone-free rate; UAS = ureteral access sheath.

Access sheath is meant to decrease complications by decreasing the intrarenal pressure, infections, and allowing multiple passages of the scope.^5,15 While the use of UAS in adults is well established, its use in pediatric population is unclear due to the potential risk of intra- and postoperative complications associated with it. There is limited evidence in literature about its efficacy and safety. There are only a few published reports directly addressing the use of UAS in the pediatric age group.^17

–22

A recently published study of 13 children weighing <20 kg who underwent FURSL showed that UAS was effective and safe in these patients.¹⁶ They had 3/13 (23%) complications which they ascribed to lower pole stones and stones of mixed composition.¹⁶ A series by Cannon et al.¹⁷ reported on 21 children with lower pole renal stones. Although UAS was only used in 43% of their patients, the SFR was 93% for stones <15 mm dropping to 33% for stones ≥15 mm. Smaldone et al.¹⁸ published a case series of 100 patients in the same year, when 24% of their patients had UAS. However, they noted a ureteral perforation in five patients, with a ureteric reimplantation needed in one patient due to ureteric stricture. However, no correlation was reported in their study between the complications that developed and use of UAS or ureteral dilation.¹⁸ Similar use of UAS was also seen in other series reporting on mean stone size of 8–15 mm.^19

–22 An effective FURSL with UAS was reported by each of the two studies, showing a good SFR in preschool children.^12,22

In our study, UAS was used in 21 cases for a mean stone size >15 mm. While the SFR was 95%, all our patients were discharged from hospital within 24 hours of admission (morning after surgery) with no procedural or long-term complications noted over a mean follow-up of 26 months.

Strengths and limitations and areas of future research

All cases of FURSL were carried out in a standardized manner using the same equipment. Our technique of doing these cases in pediatric patients has been published previously and all patients had a semirigid URS before the placement of UAS.^11,12 Being a tertiary referral center, these patients were referred from up to a distance of 206 miles. All patients were discussed in a stone multidisciplinary team (MDT) meeting where a decision to endoscopically treat these patients was made. The responsible pediatric urologist and a high-volume adult endourologist carried out these procedures with a team approach.

Our study is retrospective in nature with consecutive patients who had access sheath used included in the study. However, the study is from a single experienced MDT and the outcomes may not be generalizable. These studies should preferentially be done by experienced endourologic centers, ideally in conjunction with pediatric support. Although we had no complications, being a retrospective study potentially, these could be missed in data abstraction. Larger prospective studies with longer follow-up are therefore needed to confirm our findings and the impact on a long-term follow-up.

Although UAS is increasingly being used for pediatric FURSL, the effect of new types of stone treatment with “dusting” might change or alter the need to use it.²³ In line to a rise in ureteroscopic management of pediatric stone disease, it has also been increasingly used in pregnancy, obese, elderly patients, and those with solitary kidneys.^24
–26 The popularization of URS has also seen a reduction of the cost of performing these procedures.²⁷ With increasing use of ureteroscopy, it might allow the surgeons to tackle larger stones ureteroscopically, even in the pediatric age group.²⁸

Conclusion

The use of UAS in the treatment of pediatric renal stones is safe and feasible with good outcomes and without any long-term sequelae. However, these procedures should be performed in high-volume endourologic centers in conjunction with the pediatric team.

Footnotes

Acknowledgments

The authors would like to acknowledge the paediatric theatre team and members of the stone multi-disciplinary team.

Author Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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