Comparative Analysis of Efficacy and Complications of Robot-Assisted vs Open Dismembered Ureteral Reimplantation for Primary Obstructive Megaureter

Abstract

Introduction and Objective:

Dismembered ureteral reimplant (DUR) is done to treat primary obstructive megaureter (POM). To describe and compare outcomes between open dismembered ureteral reimplant (ODUR) vs robot-assisted laparoscopic dismembered ureteral reimplant (RALDUR).

Methods:

An IRB-approved registry was used to retrospectively identify all patients who underwent DUR for POM between 2015 and 2022. Demographics, preoperative, perioperative, and long-term outcomes were analyzed. p-Values were two sided, and a p < 0.05 was considered significant.

Results:

Our cohort consisted of 50 patients: 14 (28%) underwent ODUR, and 36 (72%) underwent RALDUR. Preoperatively, no differences were noted between RALDUR and ODUR in terms of antenatal hydronephrosis (p = 1.00), febrile urinary tract infection (p = 0.09), and reflux grade on preoperative voiding cystourethrogram (p = 0.53). Ipsilateral kidney function was 37% in the RALDUR group compared with 32% in the ODUR, with no difference between them (p = 0.74). RALDUR was associated with a longer procedure time (278 minutes vs 191 minutes, p = 0.001) and a similar rate of ureteral tapering (61% vs 86%, p = 0.18). Both cohorts had similar length of stay (p = 0.33) and IV morphine use (p = 0.84). Postoperatively, only three (6%) had Clavien Dindo grade 3b complications—one in the ODUR group who required percutaneous nephrostomy tube (PCN) placement by IR and two in the RALDUR group, one had a port-site hernia s/p repair, and one had a retained JP drain requiring removal. During follow-up, 34 (94.4%) patients in the RALDUR group had stable/improved hydronephrosis in their most recent ultrasound compared with 14 (100%) in the ODUR. Neither group underwent a reintervention procedure.

Conclusion:

RALDUR is shown to have comparable success and efficacy to ODUR. A longer procedure time is reported in RALDUR.

Introduction

Primary obstructive megaureter (POM) is one classification of megaureter, dilation of the ureter to a diameter >7 mm from 30 weeks of gestation. POM can lead to recurrent urinary tract infections (UTIs) because of delay in urine drainage and subsequently causing a progressive loss in renal function.^1

–4

Initially, POM is managed medically with antibiotic prophylaxis.⁴ Surgical management is indicated with an increase of hydronephrosis on ultrasound, a decrease in renal function, stone formation, and recurrent UTIs.^5
–7 With the advancement of minimally invasive techniques, the robot-assisted approach has gained popularity for surgical management of POMs.^8
–10

However, there is a scarcity in the literature comparing the open approach, still considered the gold standard up to date, to the robotic approach. In this study, we hypothesize that robot-assisted laparoscopic dismembered ureteral reimplantation (RALDUR) for surgical correction of POM is a safe procedure and is equivalent to open dismembered ureteral reimplant (ODUR) approach in terms of perioperative and short-term clinical outcomes.

Methods

An IRB-approved retrospective study identifying patients who underwent a dismembered ureteral reimplant for the management of POM between 2015 and 2022 was queried. Patients who had radiographical findings of obstruction with or without reflux were analyzed and stratified based on the surgical approach into ODUR or RALDUR.

Surgical indications included obstruction shown by hydroureteronephrosis with either reduced split renal function (less than 50% on the affected side), symptoms (i.e., pain), or febrile UTIs (fUTIs). The selection of surgical approach was based on the surgeon’s preference and shared decision-making. RALDUR was performed as previously described.⁹

Baseline demographics, preoperative details including hydronephrosis based on renal bladder ultrasound (RBUS), vesicoureteral reflux based on voiding cystourethrogram (VCUG), kidney function based on either MAG 3 renogram or magnetic resonance urogram, and UTIs, perioperative details including ureteral tapering, and postoperative outcomes were aggregated and analyzed. As a sub-cohort analysis, tapered ureteral reimplant were compared based on the surgical approach.

Categorical variables were reported as counts and percentages, whereas continuous variables were reported as medians with interquartile ranges (IQRs). Continuous measures were analyzed using t tests or the Wilcoxon rank-sum test and categorical measures were analyzed using Pearson’s chi-squared tests or Fischer’s Exact test. A p-value <0.05 was considered statistically significant. All statistical analyses were done using the statistical software STATA BE 18.0 (Stata Corp, College Station, TX, USA).

Results

A total of 50 children were identified during the study period. Fourteen (28%) underwent ODUR, and 36 underwent (72%) RALDUR. There was no significant difference in gender distribution or antenatal hydronephrosis between the two groups (p = 0.5 and p = 0.99, respectively). Both groups predominantly had society of fetal urology (SFU) grades III and IV hydronephrosis (100% in ODUR vs 94% in RALDUR).

High grade of vesicoureteral reflux (VUR) (grades IV and V) was noted in six (42.9%) children in the ODUR group compared with three (8.3%) children in the RALDUR group. Preoperative kidney function was similar between both groups, with the ODUR group having a median function of 32.15% (IQR: 25.78, 49) and the RALDUR group having a median function of 37% (IQR: 26.30, 51.95) (p = 0.74). The median age at surgery was 24.28 (IQR: 19.58, 57.88) months in the ODUR group and 48.11 (IQR: 21.47, 98.43) months in the RALDUR group (p = 0.12) (Table 1).

Table 1.

Demographics, Preoperative, and Perioperative Details of ODUR vs RALDUR

Characteristic	ODUR (N = 14, 28%)	RALDUR (N = 36, 72%)	p-Value
Gender, no. (%)			0.5
-Man	9 (64)	27 (75)
-Woman	5 (36)	9 (25)
Antenatal hydronephrosis, no. (%)	8 (62)	21 (58)	0.99
Hydronephrosis on RBUS, no. (%)	14 (100)	36 (100)	—
SFU grade, No. (%)			0.87
I	0 (0)	0 (0)
II	2 (0)	2 (6)
III	7 (50)	14 (39)
IV	7 (50)	20 (56)
Preoperative VCUG, no. (%)	9 (64)	18 (50)	0.53
VUR grade, no. (%)			0.11
No VUR	3 (33)	11 (61)
I	0 (0)	2 (11)
II	0 (0)	1 (6)
III	0 (0)	1 (6)
IV	2 (22)	0 (0)
V	4 (44)	3 (17)
Preoperative ipsilateral kidney function (%)	32.25 (25.78, 49)	37 (26.30, 51.95)	0.74
Preoperative febrile UTI, no. (%)	8 (57)	9 (25)	0.09
Laterality, no. (%)			0.73
Left	6 (43)	20 (56)
Right	6 (43)	13 (36)
Bilateral	2 (14)	3 (8)
Age at surgery (months)	24.28 (19.58, 57.88)	48.11 (21.47, 98.43)	0.12
Operative time (minutes)	191 (160, 258)	278 (251, 327)	0.001
Ureteral tapering, no. (%)	12 (86)	22 (61)	0.18
Length of stay (days)	2 (1, 3)	2 (1, 2)	0.33
IV morphine (mg/kg/day)	0 (0, 0.05)	0 (0, 0.05)	0.84

Estimates were given as median (quartile 1, quartile 3) or frequency (percentage).

ODUR = open dismembered ureteral reimplantation; RALDUR = robot-assisted laparoscopic dismembered ureteral reimplantation; RBUS = renal bladder ultrasound; UTI = urinary tract infection; VCUG = voiding cystourethrogram; VUR = vesicoureteral reflux.

Perioperatively, a longer procedure time was reported in the RALDUR group, with a median of 278 (IQR: 251, 327) minutes compared with 191 (IQR: 160, 258) minutes in the ODUR group (p = 0.001). Bilateral reimplantation was performed in two (14%) children in the ODUR and three (8%) children in the RALDUR group (p = 0.73). Ureteral tapering was performed in 12 (86%) children in the ODUR and 22 (61%) children in the RALDUR group (p = 0.18). The length of hospital stay was similar between the two groups, with a median of 2 days (IQR: 1, 3) in the ODUR group and 2 days (IQR: 1, 2) in the RALDUR group (p = 0.33). During hospital stay, minimal to no opioid use was required in both groups, with a median of 0 mg/kg/day (IQR: 0, 0.05, p = 0.84).

Short-term complications were reported in four (29%) children in the ODUR and six (17%) children in the RALDUR group (p = 0.44). Notably, two (5.5%) children in the RALDUR group experienced Clavien Dindo grade 3b complications: one with a port-site hernia requiring repair and another with a retained JP drain requiring removal in the OR; one (7.1%) child in the ODUR group required percutaneous nephrostomy tube placement by IR (Table 2).

Table 2.

Postoperative and Long-Term Outcomes of ODUR vs RALDUR

Characteristic	ODUR (N = 14, 28%)	RALDUR (N = 36, 72%)	p-Value
1–30 day complication, no. (%)	4 (29)	6 (17)	0.44
1–30 day Clavien Dindo grade, no. (%)			0.43
I	2 (14.3)	3 (8.3)
II	0 (0)	1 (2.7)
IIIa	1 (7.1)	0 (0)
IIIb	1^a (7.1)	2^b (5.6)
Postop febrile UTI (fUTI), no. (%)	2 (14)	3 (8)	0.61
Total no. fUTI, median (IQR)	1 (1, 1)	1 (1, 1)	—
Time from surgery to fUTI (months)	22 (3, 41)	21 (13, 44)	0.56
Postop VCUG, no. (%)	1 (7)	2 (6)	0.99
De novo or worsened reflux, No. (%)	0 (0)	0 (0)	—
Hydronephrosis status, no. (%)			—
Stable/improved	14 (100)	34^c (94.4)
De novo or worsened	0 (0)	0 (0)
Reintervention, no. (%)	0 (0)	0 (0)
Follow-up (months)	31.5 (20, 64)	23.5 (10, 56)	0.13

Estimates were given as median (quartile 1, quartile 3) or frequency (percentage).

PCN placement by interventional radiologist.

Port-site hernia s/p repair; retained JP drain s/p removal in the OR.

No postoperative RBUS data for two children.

IQR = interquartile range.

The median follow-up duration was 31.5 (IQR: 20, 64) months and 23.5 (IQR: 10, 56) months in the ODUR and RALDUR groups, respectively (p = 0.13). During follow-up, two (14%) and three (8%) children in the ODUR and RALDUR groups, respectively, experienced postoperative fUTI (p = 0.61). The incidence of fUTIs was similar between the groups, with a median of 1 (IQR: 1, 1), occurring at a median of 22 (IQR: 3, 41) months postsurgery in the ODUR and 21 (IQR: 13, 44) months in the RALDUR group (p = 0.56). Three of five patients who experienced fUTI at follow-up were not potty trained and were experiencing constipation at the time of UTI.

Postoperative VCUG was performed in one (7%) child in the ODUR group and two (6%) children in the RALDUR group (p = 0.99), with no cases of de novo or worsened reflux reported. No surgical reintervention was reported in either group, and all children had an improved or stable hydronephrosis on their most recent imaging.

In the sub-group analysis comparing tapered dismembered ureteral reimplantation procedures based on the surgical approach (Table 3), a longer operative time was observed in the robotic group with a median of 301 minutes compared with 195 minutes in the open (p = 0.01). However, no significant difference was found in terms of length of hospital stay (p = 0.17), 30-day postoperative complications (p = 0.41), and incidence of postoperative fUTIs during the follow-up period (p = 0.99). A longer follow-up duration was seen in the open group, with a median follow-up of 32 months compared with 16 months in the robotic group (p = 0.01).

Table 3.

Outcomes in Tapered Dismembered Ureteral Reimplantation Based on Surgical Approach

Characteristic	T-ODUR (N = 12)	T-RALDUR (N = 22)	p-Value
Operative time (minutes)	195 (166, 277)	301 (275, 353)	0.01
Length of stay (days)	2 (2, 3)	2 (1, 2)	0.17
1–30 day postoperative complication, no. (%)	4 (33)	4 (18)	0.41
1–30 day Clavien Dindo grade, no.			0.99
I	2	1
II	1	2
IIIa	0	1
IIIb	1	0
Postoperative fUTI, no. (%)	1	2	0.99
Total no. of fUTIs	1 (1, 1)	1 (1, 1)	—
Time from surgery to fUTI (months)	41 (41, 41)	28.5 (13, 44)	0.99
Follow-up (months)	32 (21, 74)	16 (9, 26)	0.01

Estimates were given as median (quartile 1, quartile 3) or frequency (percentage).

T-ODUR = tapered open dismembered ureteral reimplantation; T-RALDUR = tapered robot-assisted laparoscopic dismembered ureteral reimplantation.

Discussion

In this retrospective comparative study, we reported our experience with ODUR and RALDUR for management of POM, demonstrating that RALDUR had satisfactory and comparable clinical outcomes when compared with ODUR. In the present cohort, all patients have improved hydronephrosis postoperatively and no patients required reintervention regardless of surgical approach. 10% of patients experienced an episode of fUTI after dismembered reimplant which is similar to previous studies,¹¹ with no significant difference in incidence of fUTI between the two groups.

Neheman et al. demonstrated improved hydronephrosis in 34/25 patients who underwent RALDUR for primary and secondary obstructive megaureter management, with 1 patient requiring open ureteral reimplant because of high-grade VUR and fUTI, which are similar to outcomes of our robot group.¹² Similarly, Hemal et al and Fu et al. also reported success rates higher than 90% for RALDUR that translates to >90% of patients had improvement in hydronephrosis after procedure and did not require any further intervention at follow-up.^3,13

In a multi-institutional two-arm retrospective comparative study by Rappaport et al. including 48 patients who underwent RALDUR and 47 patients who underwent laparoscopic DUR for unilateral POM reported an overall success rate of 90% which was comparable to prior ODUR cohorts.¹⁴ They demonstrated the superiority of the robot-assisted approach compared with the laparoscopic approach in terms of shorter procedure length (96 minutes vs 130 minutes, p < 0.001) and hospital stay (1 day vs 5 days, p < 0.001) although having similar complication and success rates.

Zhu et al. have also described their experience with RALDUR for POM management in an infant population which was promising as it showed that all 16 infants who underwent RALDUR recovered symptomatically and had preserved renal function postoperatively.¹⁵ They reported resolution of hydronephrosis in 15/16 patients and incidence of recurrent UTI in 2/16 patients, which is comparable to studies in older children.

Both ODUR and RALDUR are safe procedures with a low incidence of major complications, and our study showed no significant difference in incidence (29% vs 17%, p = 0.44) and severity (p = 0.43) of the postoperative complications between the two approaches, similar to findings previously reported by Sforza et al.¹

Postoperative UTIs, urinary retention, and port-site hernias make up the majority of complications after RALDUR in prior studies.¹¹ In the present study, similarly in RALDUR group, one patient (6%) experienced postoperative UTI, and one patient (6%) had port-site hernia, but no incidence of urinary retention postoperatively.

Sforza et al. in an earlier study consisting of 11 patients who underwent ODUR and 12 patients who underwent RALDUR for POM investigated short-term outcomes of robotic and open dismembered reimplant. Operative time, short-term complications, and success rates were comparable between the two groups, which is in line with our findings.¹

Operative time with RALDUR, although longer in duration compared with its open counterpart, is similar in the literature.^16,17 This could be accounted to the greater number of steps and the inherent learning curve to this procedure. As more expertise is acquired, we hope a similar operative time to the open approach is achieved.

Moreover, ureteral tapering during the repair of POM remains unclear. At our institution, tapering is typically incorporated when the distal ureteral diameter is greater than 2.5 cm or if it precludes the creation of an adequate antirefluxing channel. However, surgeon preference rather than a strict size parameter is involved in the decision-making.

To our knowledge, this study is the largest comparative analysis of outcomes of RALDUR vs ODURfor POM, demonstrating comparable satisfactory safety and success of both approaches during a median follow-up duration of 26 (IQR: 13.5, 58.5) months.

There are a number of important limitations of this study. Firstly, the retrospective design of this study can contribute to a variety of biases including selection bias. The follow-up duration differences can theoretically affect the success rate but our experience tells us that failures can be identified shortly the index procedure. The single-center nature of the study, combined with a limited sample size, may restrict the generalizability of our findings for this rare pathology.

Conclusion

The present study is the largest cohort of pediatric patients with POM managed by RALDUR and ODUR, to our knowledge. This study provides a comparative analysis of ODUR vs RALDUR, demonstrating comparable safety and success during intermediate-term follow-up for both techniques.

These findings are encouraging, particularly with the increasing popularity and utilization of robotic approaches in pediatric urology, however, it is essential to consider the learning curve and economic implications of integrating robotic techniques into clinical practice.

Footnotes

Authors’ Contributions

S.A.: Conceptualization, project administration, formal analysis, writing—original draft, writing—review and editing. S.E.: Data curation, writing—original draft. E.A.: Data curation. N.K.: Data curation. M.Q.: Data curation. C.L.: Methodology. A.R.S.: Methodology, supervision, writing—review and editing. A.K.S.: Methodology, supervision, writing—review and editing. S.M.: Conceptualization, methodology, supervision, writing—review and editing.

Author Disclosure Statement

The authors declare that they have no financial disclosures or conflicts of interest.

Funding Information

No funding was received for this article.

Abbreviations Used

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