Pediatric Robot-Assisted Laparoscopic Pyeloplasty: Where Are We Now?

PURPOSE OF REVIEW: This review aims to provide an in-depth exploration of the recent advancements in robot-assisted laparoscopic pyeloplasty (RALP) and its evolving landscape in the context of infant pyeloplasty, complex genitourinary (GU) anatomy, recurrent ureteropelvic junction (UPJ) obstruction, cost considerations, and the learning curve. RECENT FINDINGS: Recent literature highlights the safety and efficacy of RALP in treating the infant population, patients with complex GU anomalies, and recurrent UPJO which were all traditionally managed using the open approach. Cost considerations are evolving, with the potential for RALP to have a lesser financial burden. In addition, the learning curve for RALP is diminishing due to robust training programs and advances in research. RALP has become the gold standard in the treatment of UPJO in pediatric urology at many children's hospitals. Surgeon comfort and research in this space allow safe and successful reconstruction in the most challenging of cases.

Utilizing RENAL nephrometry in pediatric patients undergoing nephron-sparing surgery for renal tumors: A single-institutional cohort.

INTRODUCTION: RENAL Nephrometry is a complexity score validated in adults with renal tumors and describes the likelihood of complication after partial nephrectomy (PN). Utilization in pediatrics has been limited. Thus, our goal is to quantify inter-rater agreement as well as determine how scores correlate with outcomes. We hypothesize that the RENAL Nephrometry Score is reproducible in children with renal tumors and is related to perioperative and post-operative complications. METHODS: All pediatric patients who underwent PN for a renal mass from 2006 to 2019 were identified. Patient data, operative details, and outcomes were aggregated. Pre-operative CT/MR imaging was anonymized and scored by 2 pediatric radiologists and 2 pediatric urologists using RENAL Nephrometry metrics. Statistical analysis utilized Fleiss' kappa and the intraclass correlation coefficient (ICC). Comparative analyses were performed based on Nephrometry Score <9 and ≥ 9. RESULTS: 28 patients undergoing 33 PN were identified. Median age at surgery was 3.2 years (IQR 1.8-4.0). There is moderate-good agreement across scorers on the domains of RENAL Nephrometry Score, with the lowest agreement noted for anterior vs posterior tumors. Comparing patients with scores <9 and ≥ 9, there was increased operative time (357 vs 267 min, p = 0.003) and LOS for those with a higher score, but no difference in the incidence of 30-day complications. CONCLUSION: RENAL Nephrometry Score is an easily reproducible complexity score for renal tumors in pediatric patients. Higher scores are associated with increased length of stay and estimated blood loss but not complications. Reporting of nephrometry scores in future publications on pediatric renal tumors should become standard in the literature.

Does Preoperative Testosterone Administration Decrease Complications in Distal Hypospadias Repair With Urethroplasty?

PURPOSE: Testosterone administration prior to hypospadias repair is common practice among pediatric urologists; however, its impact on surgical outcomes remains controversial. We hypothesize that testosterone administration prior to distal hypospadias repair with urethroplasty significantly decreases postoperative complications. MATERIALS AND METHODS: We queried our hypospadias database for primary distal hypospadias repairs with urethroplasty from 2015 to 2021. Patients undergoing repair without urethroplasty were excluded. We collected information on patient age, procedure type, testosterone administration status, initial visit and intraoperative glans width, urethroplasty length, and postoperative complications. To determine the role of testosterone administration on incidence of complications, a logistic regression adjusting for initial visit glans width, urethroplasty length, and age was performed. RESULTS: A total of 368 patients underwent distal hypospadias repair with urethroplasty. One hundred thirty-three patients received testosterone and 235 did not. Initial visit glans width was significantly larger in the no-testosterone vs testosterone group (14.5 mm vs 13.1 mm, P = .001). Testosterone patients had significantly larger glans width at the time of surgery (17.1 mm vs 14.6 mm [no-testosterone group], P = .001). On multivariable logistic regression analysis after controlling for age at surgery, preoperative glans width, testosterone status, and urethroplasty length, testosterone administration did show significant association with reduced odds of postoperative complications (OR 0.4, P = .039). CONCLUSIONS: This retrospective review of patients shows that on multivariable analysis there is significant association between testosterone administration and decreased incidence of complications in patients undergoing distal hypospadias repair with urethroplasty. Future studies on testosterone administration should focus on specific cohorts of patients with hypospadias as benefits of testosterone may be more evident in some subgroups than others.

Caudal anesthesia is not associated with post-operative complications following distal hypospadias repair.

INTRODUCTION: The use of caudal anesthesia at the time of hypospadias repair remains controversial as some prior studies have reported increased postoperative complication rates associated with caudal nerve block. However, these results have been called into question due to confounding factors and heterogeneous study groups. OBJECTIVE: Given the importance of identifying true risk factors associated with increased hypospadias complication rate, we examined our experience with caudal anesthesia limiting our analysis to distal repairs. We hypothesized that caudal anesthesia would not be associated with increased postoperative complications. STUDY DESIGN: We retrospectively reviewed our institutional hypospadias database from June 2007 to January 2021. All boys who underwent single-stage distal hypospadias repair with either caudal or penile block with minimum 1 month follow up were included. Records were reviewed to determine the type of local anesthesia, type of hypospadias repair, all complications, and time to complication. Association between any complication and local anesthesia type was evaluated by univariate and multivariate logistic regression analysis controlling for age at surgery and type of repair. A sub-analysis was performed for complications occurring ≤30 days. RESULTS: Overall, 1008 boys, 832 (82.5%) who received caudal and 176 (17.5%) penile block, were included. Median age at surgery was 8.1 months and median follow up was 13 months. Overall complication rate was 16.4% with 13.8% of patients requiring repeat operation. Median time to complication was 10.59 months and was significantly shorter in the caudal group (8.45 vs. 25.2 months). Caudal anesthesia was associated with higher likelihood of complication on univariate analysis; however, this was not true on multivariate analysis when controlling for age and type of repair. Caudal anesthesia was not associated with increased likelihood of complication within 30 days. DISCUSSION: Since the association between caudal anesthesia and hypospadias complications was first suggested, several studies have tried to answer this question with variable results. Our findings add to the evidence that there is no association between caudal anesthesia and increased hypospadias complications in either the short or long term. The major strengths of our study are a large, homogenous study population, robust follow up and inclusion of data from 14 surgeons over 14 years. Limitations include the study's retrospective nature as well as lack of standardized follow up protocol throughout the study period. CONCLUSIONS: After controlling for possible confounders, caudal nerve block was not associated with increased risk of postoperative complications following distal hypospadias repair.

Does ketorolac administration at the time of hypospadias surgery increase unplanned encounters in the immediate postoperative period?

INTRODUCTION & OBJECTIVE: The opioid crisis has raised concerns for long-term sequela of routine administration of opioids to patients, particularly in the pediatric population. Nonsteroidal anti-inflammatory drug use is limited in hypospadias surgery due to concerns for post-operative bleeding, particularly with ketorolac. We hypothesize that ketorolac administration at the time of hypospadias repair is not associated with increased bleeding or immediate adverse events. METHODS: A retrospective single institution study included all patients undergoing hypospadias surgery from 2018 to 2021. Outcomes measured include peri-operative ketorolac administration, opioid prescriptions, and unplanned encounters (i.e., emergency department or office visits). Comparative statistics using non-parametric and binary/categorical tests and a logistic regression were performed. RESULTS: 1044 patients were included, among whom there were 562 distal, 278 proximal and 204 hypospadias complication repairs. Ketorolac was administered to 396 (37.9%) patients and its utilization increased during the study period [Summary Figure]. Patients receiving ketorolac were older (p = 0.002) and were prescribed opioids less often after surgery (2.0% vs 5.2%, p = 0.009). There was no difference in unplanned encounters across repair types (p = 0.1). Multivariate logistic regression showed ketorolac use was not associated with an increased likelihood of an unplanned encounter. DISCUSSION: The use of NSAIDs post-operatively has traditionally been limited due to concerns about bleeding risks, however the present study displayed no significant increases in unplanned patient encounters either in the ED or outpatient clinic after ketorolac administration. Our study has several limitations including its retrospective and single-institutional design, difficulties of pain assessment in pediatric population, and possibility of under estimation of unplanned encounters due to limited access to patients' records outside of our institution. CONCLUSIONS: The use of ketorolac is not associated with an increase in unplanned encounters in children undergoing hypospadias repair. It should be considered a safe agent for perioperative analgesia to decrease opioid utilization. Further studies will evaluate long-term surgical outcomes in children receiving ketorolac after hypospadias repair.

Deferring gonadectomy in patients with turner syndrome with a genetic Y component is not a safe practice.

INTRODUCTION: Patients with Turner syndrome who harbor Y chromosome material are known to be at increased risk of developing germ cell neoplasms. The optimal timing to perform gonadectomy to reduce the risk of cancer development in these patients is not well defined. We present outcomes of Turner with a Y component (TSY) patients who underwent gonadectomy at our institution. HYPOTHESIS/OBJECTIVE: We hypothesized that tumors could occur in a significant portion of TSY patients at any age and gonadectomy can be safely performed at diagnosis rather than deferred. STUDY DESIGN: We performed an IRB-approved retrospective single center study in which we queried our institutions electronic health record to identify all patients with TSY who underwent gonadectomy at our institution from 2012 to 2021. RESULTS: In our series of 18 consecutive TSY patients, a tumor was identified in 6 patients (33.3%): 4 (22.2%) with dysgerminoma (DG) [Fig. 1] and 2 (11.1%) with gonadoblastoma (GB). DISCUSSION: Our cohort of 18 consecutive TSY who underwent gonadectomy over a 9-year period is the largest published single site cohort to date. Additionally, our patient who was found to have GB at 40 days is to our knowledge the youngest TSY patient to be diagnosed with GB in the literature. This patient's remarkably early incidence of tumor occurrence illustrates the urgency of protective gonadectomy. Given the high incidence of tumor formation in this population and the minimal morbidity associated with gonadectomy, we do not recommend delaying gonadectomy in this population for any reason. Our study is vulnerable to selection bias and confounding innate to any retrospective study. There was variation with respect to the frequency and timing of pre-operative imaging as a strict preoperative imaging protocol with sequential studies was not in place at our institution. Additionally, we do not have a comparison cohort of patients who are being followed without operative intervention as all TSY patients at our institution have undergone gonadectomy. CONCLUSION: TSY patients cannot be safely observed for tumor formation based on clinical factors such as imaging or age. Gonadectomy is safe with a low complication rate and without tumor recurrence during three-year follow-up. We continue to recommend bilateral gonadectomy in this patient population at the time of diagnosis.

Trends in opioid and nonsteroidal anti-inflammatory (NSAID) usage in children undergoing common urinary tract reconstruction: A large, single-institutional analysis.

INTRODUCTION AND OBJECTIVE: Opioid stewardship is recognized as a critical clinical priority. We previously reported marked reductions in narcotic administration after implementation of an opioid reduction protocol for pediatric ambulatory urologic surgery. We hypothesize that a decrease in post-operative and discharge opioid administration will not increase short-term adverse events. STUDY DESIGN: All pediatric patients undergoing open or robot-assisted laparoscopic pyeloplasty or ureteral reimplantation between 2015 and 2019 were included. Patients' demographics, opioid and NSAID administration, urology or pain-related emergency department (ED) visits, readmissions, and reoperations within 30 days of surgery, were aggregated. RESULTS: 438 patients, with a median age of 3.5 years (IQR 1.5-8.3) at the time of surgery, met the inclusion criteria. Annual rates of inpatient opioid administration and prescriptions decreased significantly over the study period, while rates of intra-operative, inpatient, and prescribed NSAIDs significantly increased. There was no significant difference in the occurrence of ED visits, readmissions, or reoperations within 30 days of surgery between patients who received an opioid prescription and those who did not. Multivariate regression showed that patients who did not receive an opioid prescription at discharge were found to be at a lower risk for unplanned encounters including ED visits, readmissions, or reoperations (OR:0.5, 95%CI: 0.2-0.9, p = 0.04). DISCUSSION: The present study shows the decreasing trend in inpatient opioid administration and opioid prescription after discharge, when accompanied by an increase NSAID administration, does not result in a significant change in rates of unplanned encounters and complications, similar to results from previous studies on non-urological and ambulatory urological surgeries. CONCLUSIONS: Non-opioid pain control after major pediatric urologic reconstruction is safe and effective. We found that a reduction in opioid administration can be associated with a reduced risk of unplanned ED visits, readmissions, or reoperations. Further investigations are required to corroborate this finding.

Incidence and resolution of de novo hydronephrosis after pediatric robot-assisted laparoscopic extravesical ureteral reimplantation for primary vesicoureteral reflux.

INTRODUCTION: With the advent of robot-assisted laparoscopic ureteral reimplantation (RALUR) for primary vesicoureteral reflux (VUR), understanding and minimizing its complications continues to be critical. Incidence of de novo hydronephrosis after RALUR could be indicative of an outcome that needs further study or could be a benign transient finding. OBJECTIVE: In the present study, we hypothesized that the incidence of de novo hydronephrosis after RALUR is low and resolves spontaneously. METHODS: An IRB-approved prospective single-institutional registry was utilized to identify all patients undergoing RALUR via an extravesical approach from 2012 to 2020. Patients with primary VUR and minimal (Grade I SFU) or no hydronephrosis prior to surgery were included. Patients who had other associated pathology or underwent concomitant procedures were excluded. Preoperative characteristics including VUR and hydronephrosis grades as well as post-operative clinical details and hydronephrosis grades were aggregated and analyzed. RESULTS: 86/172 (50%) patients (133 ureters), with median reflux grade of 3 (IQR: G2, G3) met the inclusion criteria. Patients underwent RALUR at a median age of 5.7 years (IQR: 3.4, 8.7) with median 36.2 months (IQR: 19.6, 63.6) follow-up. Renal ultrasound at 4-6 weeks post-op showed de novo hydronephrosis in 18 (13.5%) ureters; the complete resolution was seen in 13 ureters (72%) at a median of 4.5 months from surgery. Among the 5 with non-resolved hydronephrosis (SFU G2:4, G3:1), 2 patients (3 ureters) underwent subsequent interventions. DISCUSSION: The present study evaluating the natural history of de novo hydronephrosis after RALUR-EV performed for primary VUR, is to our knowledge the largest cohort of patients undergoing RALUR that this has been studied in. In our cohort, the incidence of de novo hydronephrosis after RALUR was 13.5%, similar to rates reported in two OUR cohorts, and significantly lower than reported incidence rates of 22-26% in several OUR cohorts, and 30% in a RALUR cohort. In the present cohort, hydronephrosis resolved spontaneously in more than 72% of cases. The median time from surgery until resolution of hydronephrosis was 4.5 (1.6, 10.5) months, which is shorter in comparison to the average time to resolution of 7.6 months, reported by Kim et al. in an earlier study. CONCLUSIONS: De novo hydronephrosis after RALUR can be followed with serial renal ultrasounds. The majority of de novo hydronephrosis post-RALUR is transient and resolves spontaneously within a year of surgery with a very low re-intervention rate.

Intrascrotal Lipoblastoma: A Rare Cause of Paratesticular Mass in a Pediatric Patient.

There is a broad differential diagnosis for a pre-pubertal child presenting with a scrotal mass including both benign and malignant etiologies. Lipoblastomas are rare benign neoplasms originating from fat cells that occur most commonly on the trunk or extremities of young children. There have been less than 20 cases of scrotal lipoblastomas reported in the literature, with the majority occurring in children less than 3 years of age. Here we present a unique case of an 18-month male presenting with a paratesticular mass found to be a lipoblastoma on final pathology.

Office Based Pediatric Urologic Procedures: A Safe and Effective Alternative to Interventions Under Anesthesia.

OBJECTIVE: To report on our experience performing office-based pediatric urologic procedures. We hypothesize that office-based interventions are safe and effective for children, avoiding unnecessary risk and cost associated with general anesthesia. METHODS: We retrospectively identified patients undergoing office-based interventions from 2014 to 2019, including lysis of penile or labial adhesions, division of skin bridges, meatotomy and excision of benign lesion. Success was defined as a completed attempt in the office. Failure includes any unsuccessful office attempts. Complications include 30-day ED visits/readmissions and recurrent skin bridge post division of skin bridge. RESULTS: We identified 1326 interventions: 491 lyses of penile adhesions (37%), 320 division of skin bridges (24%), 128 lyses of labial adhesions (10%), 348 meatotomies (26%), and 39 excisions of benign lesions (3%) [Table 1]. There was a >95% success rate reported in every procedure with an overall complication rate of 0.6%. Excision of benign lesion had 100% success rate. ED visits within 30 days are rare (0.2%), and no patients required admission after their procedure [Table 2]. The rate of recurrence was highest following lysis of labial adhesions (13.3%). Of the 54 patients who underwent retreatment, very few required general anesthesia (n = 6). CONCLUSION: Office-based urologic interventions in children are well tolerated with excellent safety and efficacy. Complications and recurrence are universally low. Ultimately, 99.5% of this cohort was managed under local anesthetics, thereby avoiding the risks of anesthesia use in the pediatric population.

Expanding the Use of Nephron-Sparing Surgery for Wilms Tumor.

Radical nephrectomy combined with contemporary chemotherapeutic and radiation therapy protocols has drastically improved outcomes for children with Wilms tumor. Patients with bilateral disease and a syndrome predisposing to tumor development have necessitated the use of nephron-sparing surgery in select cases. Success in managing these patients has increased the indication for partial nephrectomy, although current guidelines for unilateral Wilms tumor are limited. Given that children are being cured with increasing success, recent focus has shifted to long-term health outcomes in addition to tumor treatment. Specifically, renal function has an impact on long-term cardiovascular health and events. Adult outcomes with partial nephrectomy provide a guideline for a paradigm shift in the management of children with Wilms tumor, particularly with advances in imaging and adjuvant therapy. The data are limited for children undergoing partial nephrectomy for unilateral Wilms tumor and outcomes for larger tumors will need to be studied closely in future trials. Increased utilization of neoadjuvant chemotherapy could further expand the number of patients eligible for partial nephrectomy.

Quantifying Glans Width Changes in Response to Preoperative Androgen Stimulation in Patients Undergoing Hypospadias Repair.

PURPOSE: Testosterone (T) administration prior to hypospadias surgery to increase glans size remains controversial. Understanding T's effect on glans width (GW) is essential to understanding its potential impact on surgical outcomes. We hypothesized that preoperative T in prepubertal boys significantly increases GW at the time of hypospadias surgery. MATERIALS AND METHODS: Our single institutional database was queried to identify patients who underwent hypospadias surgery from 2016 to 2020, in which data for T administration and GW were available. Descriptive, nonparametric and categorical statistics were performed as indicated. RESULTS: A total of 579 patients were eligible for analysis. Median age at surgery was 0.9 years (IQR 0.6-1.6). A total of 247/579 patients (42.7%) received T. The median GW at surgery was 15 mm (IQR 13-17). When comparing patients who had T administered to those who did not, we found a significant difference in GW at surgery (16 mm vs 14 mm, p <0.001). The median change in GW from the office to surgery was 4 mm for those receiving T vs 0 mm for those not receiving T (p <0.001). We identified a greater change in GW from preoperative to intraoperative measurements in patients who received 2 doses of T vs 1 dose (4 mm vs 2 mm, p <0.001). A histogram plot revealed the distribution of GW change at surgery. CONCLUSIONS: In our prospectively collected cohort of patients undergoing hypospadias surgery, we were able to quantitate the change in GW from preoperative T. Two doses of T resulted in a significant increase in GW vs 1 dose.

Robot-Assisted Laparoscopic Ureterocalicostomy in the Setting of Ureteropelvic Junction Obstruction: A Multi-Institutional Cohort.

PURPOSE: Recurrent ureteropelvic junction obstruction (UPJO) after failed pyeloplasty is a complex surgical dilemma. The robot-assisted laparoscopic ureterocalicostomy (RALUC) is a potential surgical approach, but widespread adoption is limited due to the perceived technical challenge of the procedure. We present a multi-institutional pediatric cohort undergoing RALUC for recurrent or complex UPJO, and hypothesize that the procedure is reproducible, safe and efficacious. MATERIALS AND METHODS: A 3-center multi-institutional collaboration was initiated and medical records of children undergoing RALUC between 2012 and 2020 were retrospectively reviewed. The details on baseline demographics, perioperative characteristics and postoperative outcomes were aggregated. RESULTS: During the study period 24 patients, 7 (29%) females and 17 (71%) males, were identified. Of the patients 21 (86%) had a history of previous pyeloplasty prior to RALUC, of whom 5 (24%) had 2 prior failed ipsilateral pyeloplasties. The reason for performing RALUC was short ureter in 3 (13%), intrarenal pelvis in 5 (21%) and extensive scarring at the ureteropelvic junction locus in 16 (67%) patients. The median age of patients at time of surgery was 5.1 years (IQR: 1.9, 14.7). Of the patients 9 (38%) had percutaneous nephrostomy prior to surgery; if percutaneous nephrostomy tubes were placed for relief of obstruction, an antegrade contrast study was done postoperatively to confirm resolution of obstruction. No 30-day Clavien-Dindo Grade III-V complications were noted. During the median followup of 16.1 months (IQR: 6, 47.5), 22 (92%) had improved symptoms and hydronephrosis with no further intervention; 2 (8%) patients underwent endoscopic interventions after RALUC and both ultimately underwent nephrectomy. CONCLUSIONS: This multi-institutional cohort demonstrates that RALUC is a safe and efficacious salvage option for failed pyeloplasty or complex anatomy with an acceptable success profile, especially in cases of extensive scarring at the UPJO or an intrarenal pelvis.

Primary vs redo robotic pyeloplasty: A comparison of outcomes.

INTRODUCTION: Robot-assisted laparoscopic pyeloplasty (RALP) is a safe and efficacious option for repair of UPJO. We hypothesize that redo-RALP is technically more difficult but has comparable outcomes to primary RALP. METHODS: An IRB-approved single institutional registry was utilized to identify all patients undergoing primary or redo RALP from 2012 to 2019. Redo RALP consisted of pyeloplasty and ureterocalicostomy (RALUC). Peri-operative and post-operative details and outcomes were aggregated. Successful reconstruction was defined as resolution of symptoms, improved hydronephrosis and no need for additional procedures. RESULTS: From 399 patients who underwent UPJO repair at our center, a total of 306 with a median age of 4.9 years at surgery and a median follow-up of 18.5 months were included: 276 primary and 30 redo (21 RALP and 9 RALUC). Redo group had significantly longer procedure time and length of stay compared to the primary group. However, no significant difference was noted in the post-operative complications, need for additional endoscopic procedures or redo reconstruction, and success between the two groups. Multivariate analysis showed that when controlled for age, gender, 30-days post-operative complication and anatomy of obstruction, redo as compared to primary reconstruction did not have a significant effect on success. DISCUSSION: This study is the largest controlled cohort in the pediatric population comparing redo RALP with an established control group -primary RALP. This retrospective chart review possesses the biases innate to any retrospective study. The low number of re-operative cases as well as low rate of failure in redo RALP further complicates identification of statistically significant predictors of outcomes following redo RALP. CONCLUSION: Redo RALP is an efficient and safe approach for reconstruction of recurrent UPJO, with low complication rate and high success rate, comparable to primary RALP.

The following 3 cases were presented at the 2020 virtual PUOWG conferenceLate Presentation of Wilms Tumor in a Patient with Hemihypertrophy after Normal Screening.

An identifiable genetic malformation or predisposition syndrome is present in 18% of Wilms tumor cases. Given this, children with conditions associated with a greater than 1% risk of developing Wilms tumor are recommended to have regular surveillance imaging with renal ultrasound until age 7. Seven years is the recommended screening duration because 95% of cases will occur by this age. We present a case of a child with isolated hemihypertrophy, associated with 5% risk of Wilms tumor, who presented with a tumor after the recommended screening, at age 9, brining into question the age cutoffs currently used.

Pyeloplasty is a safe and effective surgical approach for low functioning kidneys with ureteropelvic junction obstruction.

INTRODUCTION: Indications for treatment of ureteropelvic junction obstruction (UPJO) include symptomatic obstruction, urinary tract infections, presence of an obstructive pattern on functional renal scan and/or worsening differential renal function (DRF). This paper aims to determine the relationship between preoperative DRF and surgical outcomes after pyeloplasty. We hypothesized that low preoperative DRF is not an independent predictor of pyeloplasty failure. METHODS: A retrospective chart review was performed to identify all patients undergoing pyeloplasty for UPJO between 2008 and 2019. Patients were included only if they had at least one preoperative functional scan and a minimum of one renal ultrasound post-operatively. Patients were divided into three groups based on DRF for analysis: Group 1- 0-10%, Group 2 - >10-≤20%, Group 3 - >20%. Baseline, intraoperative and postoperative characteristics, including success and complications were compared. Additional sensitivity analyses were performed comparing patients with ≤20%, and >20% function, ≤30%, and >30% function as well as an analysis of patients undergoing only minimally invasive reconstruction. RESULTS: Three hundred and sixty-four patients met inclusion criteria. We identified 8 patients in Group 1, 24 patients in Group 2 and 332 patients in Group 3. Mean procedure time was longest for the ≤10% function group (237.9 vs 206.4 vs 189.1; p = 0.01). We found no difference in 30-day post-operative complications, overall success rate or the need for additional procedures among the three groups. For patients in Group 1, we noted variation in the post-procedure DRF with a range of -2.8 to +47% change. In this group, none of patients with low DRF underwent nephrectomy. Multivariate logistic regression did not identify renal function as a predictor of operative success OR 1.00 (95% CI: 0.97-1.03) (p-value: 0.88). DISCUSSION: The results of the present study suggest that low DRF alone is not associated with worse outcomes and shows no difference in the failure rate. The incidence and type of complications were not increased for the lower functioning groups. The main limitation of this study would be its retrospective nature and single-institution experience. Furthermore, post-operative functional studies were not available for all patients, limiting the ability to draw conclusions on the change in DRF after surgery. CONCLUSIONS: In a large cohort, preoperative DRF was not predictive of pyeloplasty success rate. DRF ≤10% was not associated with higher incidence of complications or failure rate. The DRF alone should not dictate the management options available for patients with UPJO.