Managing Ureteropelvic Junction Obstruction in the Young Infant

Ultrasound and magnetic resonance imaging features of fetal urogenital anomalies: A pictorial essay

This pictorial essay focuses on ultrasound (US) and magnetic resonance imaging (MRI) features of fetal urogenital anomalies. Fetal urogenital malformations account for 30%-50% of all anomalies discovered during pregnancy or at birth. They are usually detected by fetal ultrasound exams. However, when ultrasound data on their characteristics is insufficient, MRI is the best option for detecting other associated anomalies. The prognosis highly depends on their type and whether they are associated with other fetal abnormalities.

Minimally Invasive Surgical Therapies for Ureteral Polyps: A Systematic Review

Background: Ureteral polyps are rare benign ureteral tumor. No guideline recommends that open or minimally invasive surgery is best for treating ureteral polyps. This article aims to provide a comprehensive review of the minimally invasive techniques currently available for treating ureteral polyps. Materials and Methods: We performed a comprehensive search of articles published in PubMed, using the keywords "ureteral" and "polyp," or "polyps." Results: A total of 275 studies were obtained from the literature search but 96 articles were excluded. Conclusions: Several minimally invasive approaches were developed with the advancement of medical technology, including endoscopic, laparoscopic, and robotic approaches; however, the best surgical technique was yet to be decided. Due to the advantages and disadvantages of these approaches, the best surgical approach should be tailored to each patient's needs and the surgeon's preferences and experience.

Prenatal diagnosis and outcome of fetal urinomas in relation to the underlying etiology

OBJECTIVE

Evaluation of course and outcome of pregnancies with prenatally diagnosed fetal urinoma in a single center over a 20-year period.

METHODS

Retrospective study including all prenatally suspected or diagnosed fetal urinomas. Cases were analyzed by ultrasound findings during pregnancy, comparing urinomas caused by lower urinary tract obstruction (LUTO) and ureteropelvic or ureterovesical junction obstruction (UPJO/UVJO). Course of pregnancy and outcomes were compared according to the underlying etiology.

RESULTS

87 cases of fetal urinomas were identified between 2002 and 2022. The underlying etiology was LUTO in 56.3% and UPJO/UVJO in 43.7%. Complications mainly included oligo- or anhydramnios, thoracic hypoplasia as well as associated renal abnormalities. Postnatally, loss of function (LOF) in kidneys affected by urinomas was seen in 78.6% of children overall, but significantly more often in cases of UPJO/UVJO than in LUTO (86.2% vs. 70.2%, p < 0.05).

CONCLUSION

Association of prenatal urinoma and postnatal LOF of the affected kidney is high, especially in cases caused by UPJO/UVJO. In survivors with urinoma caused by UPJO/UVJO, the general prognosis is excellent if the contralateral kidney was normal. In survivors with urinomas caused by LUTO, long-term prognosis depends on postnatal renal and pulmonary function.

Troubleshooting Tips for Diagnosing Complex Fetal Genitourinary Malformations

Fetal genitourinary anomalies can present a diagnostic challenge for the radiologist. The absence of a normally located kidney may represent agenesis or be secondary to a fusion or migration abnormality. A dilated renal pelvis should prompt evaluation for a specific cause, including ureteropelvic junction obstruction, reflux, or an obstructed duplicated system. Cystic parenchymal changes are characteristic of a multicystic dysplastic kidney but may also be seen in obstructive cystic dysplasia. There are numerous causes of megacystis including chromosomal (trisomy 18 syndrome), obstruction (posterior urethral valves, urethral atresia), or muscular dysfunction (prune belly syndrome, megacystis microcolon intestinal hypoperistalsis syndrome). Important mimics of a large bladder include hydrocolpos and urogenital sinus or cloacal malformation. Complications of genitourinary malformations are common and include oligohydramnios, urinary ascites, and urinoma. Making an accurate diagnosis often requires additional US views beyond those obtained in the standard fetal survey and occasionally performing fetal MRI. The appropriate use of orthogonal T2-weighted sequences, in conjunction with diffusion-weighted images for evaluation of the kidneys and gradient-recalled-echo sequences for evaluation of T1-hyperintense meconium in the colon, can play an integral role in diagnosis. Accurate diagnosis of fetal genitourinary malformations is vital to direct patient counseling and pregnancy management as outcomes are highly variable. Some conditions can be surgically corrected quite simply, some require multiple complex procedures, and some are lethal. The authors offer troubleshooting tips to narrow the differential diagnosis for four observations: unilateral absent kidney, dilated renal pelvis, cystic renal parenchyma, and megacystis and its mimics. ©RSNA, 2023 Test Your Knowledge questions are available in the Online Learning Center.

Risk factors for adverse outcomes after pediatric pyeloplasty: A retrospective cohort study

PURPOSE

To identify the risk factors for adverse outcomes after pediatric pyeloplasty.

METHODS

We conducted a retrospective review of all children under the age of 14 years who underwent primary pyeloplasty for unilateral ureteropelvic junction (UPJ) obstruction at a single teaching hospital in Tunisia between January 1, 2013, and December 31, 2022.

RESULTS

A total of 103 patients were included. Median age of patients at surgery was 27 months (interquartile range [IQR], 13-44). On ultrasound, median renal pelvic anteroposterior diameter was 3.2 cm (IQR, 2.3-4), and the median renal cortex thickness (RCT) was 2.5 mm (IQR, 2-3.5). Median differential renal function (DRF) on preoperative radionuclide renal scan was 40% (IQR, 30-46). Postoperative adverse outcomes occurred in 28 patients (27.2%). These included 19 cases of urinary tract infections (UTIs), 11 cases of UPJ restenosis, four cases of UPJ leakage, two cases of urinoma, and two cases of diversion-related complications. Multivariate logistic regression analysis revealed two factors significantly and independently related to postoperative negative outcomes: RCT <3 mm and DRF > 50%.

CONCLUSION

Our study demonstrated that preoperative RCT on ultrasound of less than 3 mm and preoperative DRF on radionuclide renal scan of more than 50% were independent risk factors for adverse outcomes following pediatric pyeloplasty. These factors could be of interest in identifying, early on, patients who will develop postoperative negative outcomes, giving them more attention and support, and explaining the prognosis to the patient and family.

Determination of tissue tracer transit of Technetium-99m-mercaptoacetyltriglycine diuretic renography in infants with suspected ureteropelvic junction obstruction - A multicenter prospective observational study

INTRODUCTION

There is an ongoing controversy regarding management of ureteropelvic junction obstruction in infants, with a shift towards a non-operative approach. However, precise predictors of outcome are lacking. Recent studies postulated a high prognostic value of Technetium-99m-mercaptoacetyltriglycine tissue tracer transit with regard to the development of an impaired differential renal function and its potential improvement following pyeloplasty.

OBJECTIVE

To evaluate the prognostic value of Technetium-99m-mercaptoacetyltriglycine tissue tracer transit for the occurrence of changes in differential renal function in infants with suspected unilateral ureteropelvic junction obstruction in a prospective observational multicenter study.

STUDY DESIGN

Infants below 3 months of age with a unilateral isolated hydronephrosis ≥ grade 3 received ultrasound and Technetium-99m-mercaptoacetyltriglycine diuretic renography at two different time points (timepoint 1 and timepoint 2). Data were analyzed at local centers and at the study center and were collected in an internet-based database system. Tissue tracer transit was determined for each diuretic renography, inter-observer variation for tissue tracer transit and standard parameters for judgement of differential renal function development were assessed.

RESULTS

Thirty-seven patients were analyzed. Median age was 11 weeks (7-15) at timepoint 1 and 26 weeks (19-33) at timepoint 2. A delayed tissue tracer transit at timepoint 1 was not associated with deterioration of differential renal function at timepoint 2 in both, locally (10/37 cases) and centrally (4/37) analyzed cases. However, sensitivity and specificity were poor. The intraclass correlation coefficient comparing local and central findings of tissue tracer transit and renal drainage demonstrated poor or fair agreement. Analysis of standard parameters for differential renal function development revealed a prognostic value only for the dichotomized anteroposterior renal pelvic diameter (APD, p = 0.03, 95%-CI 1.2-22.2).

DISCUSSION

Regarding the primary endpoint of our study, we could not confirm the hypothesis that delayed tissue tracer transit reliably predicts a subsequent decline in differential renal function in the cohort of patients studied. Whether the low age of the patients, technical problems in the correct assessment of tissue tracer transit by the investigator in early infancy, the study design, or the parameter itself played a role is debated.

CONCLUSION

In the presented setting tissue tracer transit was not useful as a predictive parameter for deterioration of differential renal function in infants with suspected unilateral ureteropelvic junction obstruction. Sensitivity and specificity of tissue tracer transit were not sufficient for risk stratification. Improved utility of tissue tracer transit as a marker might be achieved using a different study setting.

Sudden-onset hypertension leading to the diagnosis of unilateral hydronephrosis due to ureteropelvic junction obstruction

We present a case of a 41-year-old female who developed hypertension over a three-month period and was subsequently diagnosed with ureteropelvic junction obstruction (UPJO). The patient came to our department with elevated blood pressure. Blood examinations revealed normal renal function, hypokalemia and increased renin-angiotensin system (RAS) activity, as indicated by elevated level of plasma renin activity and plasma aldosterone level. A computed tomography imaging further revealed dilation of the left renal pelvis, atrophy of the left kidney, and indications of obstruction at the junction between the renal pelvis and ureter. Surgical intervention in the form of a left pyeloplasty successfully resolved the unilateral hydronephrosis, corrected the elevated RAS activity, normalized the blood pressure, and ameliorated the hypokalemia. This case emphasizes that elevated blood pressure might be the sole clinical indication of hydronephrosis. It's crucial to consider hydronephrosis due to UPJO as a potential cause, especially when diagnosing hypertension associated with RAS hyperactivity in young adults. It also highlights the effectiveness of surgical intervention in treating hypertension in such scenarios.

Sex differences in children operated with pyeloplasty for pelvoureteric junction obstruction

PURPOSE

Pelvoureteric junction obstruction (UPJO) is a common cause of hydronephrosis in children but no previous studies have evaluated differences between boys and girls operated with pyeloplasty. This study aimed to evaluate potential differences between sexes in children operated with pyeloplasty for PUJO in terms of presentation, surgery, and long-term results.

METHODS

Data was retrospectively collected from all children operated on with pyeloplasty between January 2002 and December 2020. Data contained several variables covering presentation, surgery, and long-term results.

RESULTS

In total, 194 patients were included of which 126 (64.9%) were boys. There were no significant differences in prenatal findings, pelvic dilation on ultrasound, function of the affected kidney, surgical method, obstruction type, resolution of hydronephrosis, or improvement of function. Boys presented with pain more often than girls (47.4 vs 25.0%, p < 0.01) while girls were more prone to infections preoperatively (17.2 vs 7.0%, p = 0.04). All nine patients requiring reoperation were boys (p = 0.03).

CONCLUSION

Girls with UPJO seem to experience infections as presenting symptoms more often than boys, while boys significantly more often present with pain. There is also a higher percentage of boys needing reoperation.

Progressive Ureteropelvic Junction Obstruction and Renal Function Deterioration in Adult, Even in a Short Period of Time

Introduction

The ureteropelvic junction obstruction is more common in children; however, it can also affect adults. The management of this condition has shifted toward a nonoperative approach with serial ultrasonography and renography. Case Presentation. The ureteropelvic junction obstruction imaging with significant renal function deterioration in an adult patient is described in this report. Laparoscopic exploration revealed aberrant vessels that compress the ureteropelvic junction against the lower pole of the kidney.

Conclusion

It is important to consider that some of the ureteropelvic junction obstruction cases can get worse even in a short period of time.

Are weight or age limits for pediatric laparoscopic pyeloplasty? Results of a multicentric study

INTRODUCTION

Anderson-Hynes pyeloplasty is the technique of choice for the treatment of pyeloureteral junction obstruction (PUJO) with an excellent success rate. Minimally invasive surgery has become the standard of care for the management of PUJO in children. Although it has been comparable to the open approach at all levels, its diffusion or employment in younger children has not been widely adopted. Our aim is to evaluate laparoscopic pyeloplasty outcomes from international academic centers in children under 1 year of age, focusing on feasibility and outcomes including possible complications.

MATERIALS AND METHODS

This is review of consecutive infants under 1 year of age who underwent laparoscopic pyeloplasty between 2009 and 2018 with more than 12 months of follow-up. Seven different training centers with different backgrounds participated in this study. Evaluation was carried out with ultrasound and renogram before and after surgery. Demographic data, perioperative characteristics, complications, and results are described and analyzed.

RESULTS

Over 9 years, 124 transperitoneal laparoscopic Anderson-Hynes pyeloplasties were performed on 123 children under 1 year of age; 88 males and 35 females, with 1 case of bilateral PUJO. Of the 124 renal units, 86 were left-sided. Mean age at surgery was 6.6 months (1 week-12 months), with 56% (n = 70) done before 6 months of age. Mean weight at surgery was 6.8 kg (3-12 kg), with 59% (n = 73) weighing less than 8 kg. Mean operative time (skin-to-skin) was 150 min (75-330 min). After a mean follow-up of 46 months (12-84 months), 12 (9%) patients developed complications, with only 1 needing a redo pyeloplasty also done laparoscopically. One child, with deterioration in renal function, underwent nephrectomy.

CONCLUSION

Laparoscopic pyeloplasty under 1 year of age and/or less than 12 kilos is feasible with lower complication rate. Furthermore, age younger than 6 months and weight less than 8 kg are no longer limiting factors for a successful pyeloplasty as shown by this multicentre study.

Enhanced recovery management in pediatric pyeloplasty: outcomes in a single institution and tips for improvement

OBJECTIVE

We report the application of enhanced recovery after surgery (ERAS) regimens to pediatric patients undergoing laparoscopic pyeloplasty (LP), aiming to guide the practice of ERAS in pediatric LP.

METHODS

From October 2018, we prospectively implemented a twenty-point ERAS regimen, including a modified LP procedure, for pediatric UPJO patients in a single institution. Data from 2018 to 2021 were collected and analyzed retrospectively. The variables gathered included: demographics, preoperative details and recovery elements. Outcomes were postoperative length of stay (POS), readmission rate, operation time and blood loss.

RESULTS

A total of 75 pediatric patients (0-14 years) were included. The mean POS was 2.4 ± 1.4 days, shorter than that in recent studies in China (3.3 ± 1.4 days, 6 (3-16) days). None were redo, and six restenosis (8%) were improved after treatment with ureteral balloon dilatation. The mean operation time was 257.9 ± 54.4 min, and blood loss was 11.8 ± 10.0 ml. In the univariable analysis and multivariable analysis, no external drainage, sacral anesthesia, and withdrawal of the catheter on day one were independently associated with a POS of ≤ 2 d (p < 0.05).

CONCLUSION

The implementation of this ERAS protocol for pediatric LP has resulted in a shorter length of stay without a higher readmission rate. Surgery techniques, drainage management and analgesia are the key to further improvement. ERAS for pediatric pyeloplasty should be encouraged.

Fetal uropathies: pre- and postnatal imaging, management and follow-up

Congenital uropathies are the most common fetal anomalies. They include a wide spectrum of anomalies ranging from mild pelvis dilation to complex urinary tract malformations. Prenatal imaging not only allows for their diagnosis but, in experienced hands, it can differentiate obstructive from refluxing or malformative uropathies. Such precise prenatal information allows for intervention before birth in select cases or for adapting the postnatal workup to provide a better long-term outcome. For the different types of congenital uropathies, we describe their prenatal presentations on US and the complementary role of fetal MRI where indicated. We correlate these findings with postnatal workup and summarize the updated neonatal diagnostic and clinical/surgical management.

Laparoscopic versus robot-assisted pyeloplasty in infants and young children

OBJECTIVE

To compare the characteristics of conventional laparoscopic pyeloplasty (LP) and robotic-assisted laparoscopic pyeloplasty (RALP) in infants and young children with ureteropelvic junction obstruction (UPJO).

METHODS

We performed a retrospective study of patients (age: 0-36 months) who underwent dismembered pyeloplasty (Anderson-Hynes) with the fourth-generation RALP or traditional LP between April 2020 and December 2020.

RESULTS

A total of 33 patients with UPJO were enrolled: 12 underwent RALP (9 left side; 3 right side) and 21 underwent LP (18 left side; 3 right side). In the RALP group, the median patient age was 17 months (range: 5-36 months). In the LP group, the median patient age was 9 months (range: 2-36 months) (P = 0.182). The mean operation times were 120.25 ± 37.54 min (RALP) and 156.10 ± 51.11 min (LP) (P = 0.042), and the mean lengths of hospital stay were 6.42 ± 1.62 days (RALP) and 8.19 ± 2.25 days (LP) (P = 0.023). Removal of the drainage tube was performed after 3.08 ± 0.69 days (RALP) and after 4.76 ± 1.81 days (LP) (P = 0.001). The postoperative pain showed no significant difference. The mean hospitalization costs were 61464.75 ± 2800.53 yuan (RALP) and 22169.52 ± 3442.15 yuan (LP) (P < 0.001). The mean follow-up time was 10-18 months. Significant improvements in the anteroposterior diameter and parenchymal thickness were observed after surgery. Conversion to laparotomy was not performed. No short-term complications occurred during postoperative hospitalization and follow-up.

CONCLUSION

RALP has the advantages of less trauma and faster recovery. It can be safely and effectively performed in infants and young children, and its effectiveness is similar to that of traditional LP.

The effect of ureteropelvic junction obstruction and pyeloplasty on somatic growth during infancy

Background

Evidence regarding the impact of perinatal ureteropelvic junction obstruction (UPJO) and surgical correction during infancy, on somatic growth are scarce. Understanding these impacts could help advise parents and aid in treatment decision making.

Objectives

To assess the impact of unilateral UPJO and surgical correction on somatic growth in infants diagnosed antenatally and treated during infancy.

Design

A retrospective bi-institutional analysis of somatic growth in patients under 2 years who underwent dismembered pyeloplasty for the treatment of UPJO was conducted.

Methods

We evaluated patients who were diagnosed with unilateral hydronephrosis during pre-natal ultrasound screening for detection of fetal anomalies between May 2015 and October 2020. The height and weight of patients who were diagnosed with UPJO were recorded at the age of 1 month, time of surgery, and 6 months after surgery. Standard deviation scores (SDSs) for height and weight were calculated and compared.

Results

Forty-eight patients under the age of 2 years were included in the analysis. Median age and weight at pyeloplasty were 6.9 months and 7.5 kg. At 1 month, the median SDS for weight in the entire cohort was -0.30 [interquartile range (IQR): -1.0 to 0.63] and the median SDS for height was -0.26 (IQR: -1.08 to 0.52). In 22.9% of patients (11/48), weight and height were below -1 age-appropriate standard deviations, and 6.3% (3/48) were below -2 standard deviations, suggesting growth restriction. When comparing SDS for the entire cohort, there was no significant difference corelated to measurement time or effect of surgery. In the growth restricted cohort, we found a significant improvement in linear growth for height, which was demonstrated between birth and surgery as well as after surgery.

Conclusion

Infants with unilateral UPJO diagnosed antenatally as a single anomaly may be at an increased risk of somatic growth restriction in comparison with the general population. In children with growth restriction at time of birth, height seems to improve regardless of surgical treatment. Pyeloplasty during infancy does not seem to negatively affect somatic growth. These findings can be used to counsel parents regarding the potential effects of UPJO and pyeloplasty.

Febrile urinary tract infection after Double-J stent removal is associated with restenosis after laparoscopic pyeloplasty: A propensity score matched analysis of 503 children

OBJECTIVE

To analyze the association between the febrile urinary tract infection (fUTI) after Double-J (DJ) stents removal and restenosis after laparoscopic pyeloplasty (LP).

STUDY DESIGN

We retrospectively reviewed the clinical data of patients who were treated with transperitoneal LP for ureteropelvic junction obstruction from 2016 to 2020. Patients were divided into two groups according to whether they developed fUTI after DJ stent removal within 48 h. The 1:3 Propensity Score Matched (PSM) method was used to balance confounding variables.

RESULTS

503 patients were included in the study. 28 (5.57%) patients developed fUTI after DJ stent removal. Compared with the non-fUTI group, age was younger, and weight was lower (P < 0.05) in the fUTI group. Restenosis occurred in 11 (2.2%) patients, of which six patients developed fUTI after DJ stent removal. The revision surgery rate in the fUTI group was significantly higher than in the non-fUTI group (21.4% vs. 1.1%, P < 0.01). After PSM, the results remained consistent. For 492 patients without restenosis, 22 patients developed fUTI. Compared with the non-fUTI group, the larger anteroposterior diameter (APD) and higher APD/cortical thickness (P/C) ratio were observed in the fUTI group at three months and six months postoperatively (P < 0.05), but the difference vanished at 12 months and 24 months after surgery (Figure).

DISCUSSION

FUTI after DJ stent removal is not uncommon after LP, and surgeons are often concerned about the possibility of restenosis. In the present study, although our results demonstrated a significant association between them, restenosis patients comprise only about 20% of fUTI patients. Based on our clinical observations, fUTI is often developed in children from 1 to 6 years of age, and the younger patients may be afraid of voiding because of the postoperative pain after DJ stent removal. Besides, intraoperative manipulation of DJ stent removal may lead to transient edema in the anastomotic site, causing the fUTI. For patients who develop fUTI after DJ stent removal but without persistent symptoms, the transient worsening of hydronephrosis during the early postoperative period may not impact long-term outcomes (As shown in Figure). Additional follow-up is needed to prevent the deterioration of renal function.

CONCLUSIONS

Our result demonstrated that fUTI after DJ stent removal is associated with restenosis after LP. For fUTI patients without restenosis, APD and P/C ratio exhibited transient worsening at three months and six months postoperatively, decreasing gradually during follow-up. Patients who develop fUTI after DJ stent removal should be monitored.

Clues for the early loss of renal function in congenital hydronephrosis: Analysis of renal pelvis collagen ratio, diuresis renography and upper urinary tract morphology

INTRODUCTION

Diagnosing real urinary obstruction and surgical decision making for the operative correction of urinary obstruction, are still problematic in congenital hydronephrosis (CH). Compliance of the renal pelvis is one of the important defense mechanisms of renal parenchyma against urinary obstruction. We observed early loss of function in some cases of CH with low and moderate anteroposterior diameter of the renal pelvis (APDRP).

OBJECTIVE

To evaluate structural properties of the renal pelvic tissue of patients with CH and the relation of these structural properties with renal function and Anteroposterior diameter of the renal pelvis.

STUDY DESIGN

Ureteropelvic junction (UPJ) excised during UPJ obstruction operations from 2013 to 2019 were evaluated histopathologically. The patients were divided into the two groups according to initial renal function, i.e. group with initial preoperative differential renal function (DRF) less than 35% and group with initial DRF greater than 35%. The percentage of collagen to whole tissue area were analyzed using image processing program. The relationship between DRF and tissue collagen ratio, SFU and APDRP was evaluated.

RESULTS

There were 5 patients in the DRF <35% group and 16 patients in the DRF >35% group. However, APDRP's of the DRF <35% group were also significantly lower than the DRF >35% group. The collagen distribution in the muscle layer was more prominent in the DRF <35% group. Proportionally, percentage of collagen stained surface was significantly higher in DRF <35% group.

DISCUSSION

There are numerous histopathological studies evaluating the cause of UPJ obstruction. Besides these studies that are oriented to etiology, there are many studies comparing the histopathological changes at UPJ with surgical outcome and prognosis. In the present study, we found that renal pelvis collagen ratio was significantly increased in patients with lower APDRP and with severe renal function loss. This increase in the collagen content in the renal pelvis have been shown to affect the compliance negatively and decrease APDRP, which leads to a faster loss of renal function. Thus, pelvic structural changes accompanying UPJ obstruction may aggravate urinary obstructive process.

CONCLUSION

Increased renal pelvis collagen ratio negatively affects the expansion of the renal pelvis, which is one of the protective mechanisms of the renal parenchyma, and may be one of the triggering mechanisms of early loss of renal function.

Initial observational management of hydronephrosis in infants with reduced differential renal function and non-obstructive drainage parameters

INTRODUCTION

Hydronephrosis secondary to ureteropelvic junction (UPJ) obstruction is a common finding in infants with prenatally-diagnosed hydronephrosis and often results in pyeloplasty due to obstructive drainage parameters and/or renal function compromise. However, little is known regarding the natural history of hydronephrosis with reduced differential renal function (DRF) but non-obstructive drainage.

OBJECTIVE

We sought to explore our experience with initial observational management of these patients.

STUDY DESIGN

A retrospective review of our institutional database of all diuretic MAG-3 renal scans obtained between 2000 and 2016 was performed. We included patients with antenatally-detected unilateral hydronephrosis ≥ SFU grade 2, first MAG-3 scan prior to 18months of age, DRF <40% and post-furosemide half-time (T1/2) <20 min. Exclusion criteria were: hydroureter, VUR, solitary kidney, duplication anomalies. Outcomes of interest were a progression of T1/2 ≥ 20 min and/or further decline in DRF >5%.

RESULTS

Of 704 patients with unilateral hydronephrosis, 91 had DRF≤40%, of which 29 (18 boys, 11 girls) met our inclusion criteria and were followed for a mean of 2.8 years (1.4 months-6.6 years). Mean age at first sonogram was 2.3 months. 2 patients had SFU grade 2, 16 had grade 3, and 9 had grade 4 hydronephrosis, and 2 unknown grade. Median half-time on initial MAG-3 scan across all patients was 10 min (3-20 min). Initial MAG3 scan was performed at a median of 2.3 months of age (0.3-17 months). 22/29 patients had >1 MAG3 scan. Of the 7 remaining, 5 were lost to follow-up and 2 demonstrated improvement in hydronephrosis. Worsening drainage occurred in 10/22(45%), median final T1/2 was 45.5 min 8 of these underwent pyeloplasty and 2 were lost to follow up. 4/22 patients (18%) had progressive decline in DRF (mean 8.3%, range 6-10%). 3/4 maintained non-obstructive drainage patterns and stable/improved hydronephrosis, and 1 underwent pyeloplasty. 13/18 remaining patients had stable DRF and 5 had improvement in DRF. 7(39%) of these underwent surgery for worsening drainage (Summary Figure). Overall, 7/29(24%) patients had sufficient resolution of hydronephrosis to be discharged from our care, 8(28%) are under continued observation, 9(31%) underwent pyeloplasty, and 5(17%) were lost to follow-up. In the observational group [median follow-up 4.5 years (3.7-6.6 years)], all 8 demonstrated improved non-obstructive drainage (T1/2 <20 minutes) and/or improvement in hydronephrosis. 4/10(40%) with DRF <35% underwent pyeloplasty versus 5/19(26%) with DRF 35-40%(p=0.67).

CONCLUSION

Initial observational management of unilateral hydronephrosis with reduced DRF and nonobstructive drainage is recommended as most kidneys maintain nonobstructive drainage and do not demonstrate further decline in DRF. Even when DRF decreases, the majority remain non-obstructive. Worsening drainage over time more often leads to the decision for pyeloplasty rather than change in DRF.

Comparing accuracy of urinary biomarkers in differentiation of ureteropelvic junction obstruction from nonobstructive dilatation in children

Multiple urinary biomarkers have been reported in differentiation of nonobstructive dilatation (NOD) from ureteropelvic junction obstruction (UPJO). In this meta-analysis, we compared the accuracy of common urinary biomarkers applicable to UPJO. A systematic literature review of electronic databases was conducted for: (UPJO) OR (NOD) AND (urinary biomarkers) AND (children) for articles published in the last decade. PRISMA guidelines were used to exclude duplicate and erroneous articles. Meta-analysis involved risk of bias analysis, heterogeneity assessment, and comparison of sensitivity/specificity by forest plot analysis using MetaXL 5.3. Among the 264 articles analyzed, 19 articles met the inclusion criteria and reported the following: neutrophil gelatinase-associated lipocalin (NGAL), monocyte chemotactic protein-1 (MCP1), carbohydrate antigen 19-9 (CA 19-9), kidney injury molecule (KIM1), epidermal growth factor (EGF), and interferon gamma induced protein-10 (IP10). There was substantial heterogeneity among articles. There was wide variation in applied cut-offs among studies. Overall sensitivity was highest at 87% for CA 19-9 while overall specificity was highest at 76% for NGAL. Overall accuracy was highest at 78% for CA 19-9 followed by 77% for NGAL and 75% for KIM1. In this meta-analysis, the overall accuracy was highest for CA 19-9 followed by NGAL and KIM1. The small number of studies for CA 19-9 and considerable heterogeneity for all should be considered while interpreting these findings. Based on the current meta-analysis, we support a panel of biomarkers combining NGAL, KIM, and CA 19-9 for the best diagnostic accuracy of UPJO in children.

A systematic review of underlying genetic factors associated with ureteropelvic junction obstruction in stenotic human tissue

OBJECTIVE

Genetic factors are implicated in the development of ureteropelvic junction obstruction (UPJO). The aims of this study were: 1) condense and examine the existing data in studies containing information regarding differential gene expression in tissues from patients with UPJO and 2) investigate associations between genetic markers and their related pathways.

MATERIALS AND METHODS

A systematic review of studies published between January 2000 and September 2021 was conducted using the following databases: Ovid/Medline, PubMed, Wiley Cochrane Central Register of Controlled Trials, Web of Science, and Scopus. Of 249 studies, 10 were included in the final analysis. The search was performed using the terms "ureteropelvic junction obstruction", "genetic", "gene", and "gene expression". Literature pertaining to differential gene expression in UPJO patients as compared to healthy controls was identified. Studies containing gene expression and quantification of molecular data carried out directly on stenotic tissue samples were selected for analysis. Gene network connections and functional analyses were then determined using MetaScape software.

RESULTS

From the ten studies identified for analysis, fifteen genes were noted as differentially expressed. In UPJO patients, nine genes were upregulated (ET1, ACTA2, MCP-1, TGFB1, NFKB1, IL-6, HIF1A, S100A1, SYP) and six were downregulated (ADM, NOS2, EGF, PDGFRA, UCHL1, NGFR). These genes were principally involved in HIF-1 signaling pathway, blood vessel development, positive regulation of signaling receptor activity, and Ras signaling pathway.

CONCLUSIONS

A potential link exists between genes related to hypoxia, excessive fibrous tissue formation, and inflammation in the development of UPJO, and these connections merit more detailed, tissue level investigations in UPJO patients. The outcomes of this systematic review may lay the groundwork for the development of future targeted therapies and novel biomarker detection for treatments, early detection, and possible prediction and prevention of development of UPJO.

A Comparative Analysis of Robot-Assisted Laparoscopic Pyeloplasty in Pediatric and Adult Patients: Does Age Matter?

We investigated factors that affect the surgical outcomes of robotic pyeloplasty by comparing the surgical results of pediatric and adult patients with ureteropelvic junction stricture (UPJO). We retrospectively reviewed patients who underwent robotic pyeloplasty for UPJO between January 2013 and February 2022. The patients were categorized into two groups: the pediatric (≤18 years) and adult (>18 years) groups. The perioperative and postoperative outcomes and surgical complications were comparatively analyzed. Prognostic factors for predicting surgical failure were analyzed with multivariable logistic regression analysis. The pediatric group showed longer total operation and console times. The mean pain score was lower in the pediatric group than in the adult group on days 1 and 2 after surgery. The average amount of morphine used in the pediatric group was lower during postoperative days 0−2. No differences in the length of hospital stay, incidence of surgical failure, and incidence of urolithiasis requiring treatment after robotic pyeloplasty were observed between the groups. The only factor that predicted surgical failure was a history of urolithiasis before surgery. The results showed that age did not affect the surgical outcome.

Feasibility, safety and effectiveness of laparoscopic transperitoneal pyeloplasty in children: Ain Shams University early experience

Background/purpose

Laparoscopic pyeloplasty (LP) is now widely recognized as a minimally invasive alternative for the surgical repair of ureteropelvic junction obstruction (UPJO) in paediatrics. In this work, we aim to evaluate the feasibility, safety and effectiveness of LP in our early experience.

Patients and methods

Between April 2019 and April 2020, patients presented with indication for surgical repair of UPJO were offered laparoscopic transperitoneal Anderson-Hynes pyeloplasty. Demographic data, preoperative investigations, operative data and intra- or postoperative complications, as well as short and mid-term follow-ups were recorded.

Results

During the specified period, 13 patients underwent LP (8 girls and 5 boys) with a median age of 12 months (range from 5 to 150 months). There was no conversion to open approach with operative time ranging from 120 to 240 min (mean = 175 ± 34 min). No intra- or postoperative complications were encountered. One to 2 years postoperative follow-up was performed (median = 18 months) in 11 patients. One patient discontinued follow-up after 1 month and another after 6 months. Follow-up PAUS showed a reduction in the anteroposterior diameter of the renal pelvis in all cases. Postoperative diuretic renal scans (DTPA renography) were done for three patients with a persistent anteroposterior diameter of the renal pelvis greater than 20 mm which showed improvement in the washout. All patients had a good cosmetic outcome.

Conclusion

In our early experience in LP, we found the procedure a safe, feasible and effective technique in managing UPJO in children and infants with good cosmetic outcome.

Level of evidence

This is a case series study (level IV evidence).

Quantitative renal magnetic resonance imaging: magnetic resonance urography

The goal of functional renal imaging is to identify and quantitate irreversible renal damage and nephron loss, as well as potentially reversible hemodynamic changes. MR urography has evolved into a comprehensive evaluation of the urinary tract that combines anatomical imaging with functional evaluation in a single test without ionizing radiation. Quantitative functional MR imaging is based on dynamic contrast-enhanced MR acquisitions that provide progressive, visible enhancement of the renal parenchyma and urinary tract. The signal changes related to perfusion, concentration and excretion of the contrast agent can be evaluated using both quantitative and qualitative measures. Functional evaluation with MR has continued to improve as a result of significant technical advances allowing for faster image acquisition as well as the development of new tracer kinetic models of renal function. The most common indications for MR urography in children are the evaluation of congenital anomalies of the kidney and urinary tract including hydronephrosis and renal malformations, and the identification of ectopic ureters in children with incontinence. In this paper, we review the underlying acquisition schemes and techniques used to generate quantitative functional parameters including the differential renal function (DRF), asymmetry index, mean transit time (MTT), signal intensity versus time curves as well as the calculation of individual kidney glomerular filtration rate (GFR). Visual inspection and semi-quantitative assessment using the renal transit time (RTT) and calyceal transit times (CTT) are fundamental to accurate diagnosis and are used as a basis for the interpretation of the quantitative data. The importance of visual assessment of the images cannot be overstated when analyzing the quantitative measures of renal function.

Outcome analysis of immediate and delayed laparoscopic pyeloplasty in infants with severe ureteropelvic junction obstruction

OBJECTIVE

The treatment timing of ureteropelvic junction obstruction (UPJO) in infants remains controversial. This study aimed to compare the recovery effect of renal morphology of immediate and delayed laparoscopic pyeloplasty in infants with severe UPJO.

METHODS

The infants with severe UPJO-induced hydronephrosis who underwent laparoscopic pyeloplasty according to their age at the time of surgery [the immediate treatment (IT) group: ≤1 month of birth, the delayed treatment (LT) group: 3-6 months of birth] in our center between 2010 and 2019 were enrolled in this study. Ultrasonography was used to assess renal morphology, including anteroposterior diameter (APD) of a pelvic, parenchymal thickness (PT), polar length (PL), and Society of Fetal Urology (SFU) grade. Preoperative and postoperative renal morphological outcomes at 6, 12, and 24 months were measured and compared.

RESULTS

During this period, a total of 135 patients were assigned to receive either IT (n = 73) or LT (n = 62) and were included for analysis. There were no significant differences in renal morphology indices at baseline between groups of IT and LT. The APD, PT, and PL in both groups all recovered to certain degrees compared with those at baseline, however, the IT group recovered more significantly than the LT group. Despite there being no significant difference in SFU grade between the two groups before and after surgery, the reduction of SFU grade in the IT group was more significant than that in the LT group during the 6-, 12- and 24-month follow-up periods. The PL, SFU, and APD were greater in the IT group than in the LT group at 6, 12, and 24 months of follow-up. At 6 months PL was not significantly higher between the two groups, while the outcome was significantly different at 12 months and 24 months.

CONCLUSION

Immediate laparoscopic pyeloplasty for the infant with severe ureteropelvic junction obstruction is effective, and it can accelerate the recovery of renal morphological indices in infants with severe UPJO-induced hydronephrosis.

Ureteropelvic junction obstruction in infants: Open or minimally invasive surgery? A systematic review and meta-analysis

INTRODUCTION

The historical gold standard treatment for ureteropelvic junction obstruction (UPJO) was the open Anderson-Hynes dismembered pyeloplasty (OP). Minimally invasive surgery (MIS) procedures, including laparoscopic pyeloplasty (LP) and robot-assisted laparoscopic pyeloplasty (RALP), have been reported to achieve better outcomes (i.e., decreased morbidity, reduced postoperative pain, superior esthetic results, and shortened length of hospital stay, LOS), with a success rate similar to OP. The main limitation of the MIS approach is the age and weight of patients, limiting these procedures to children >1 year. This study aims to evaluate the feasibility and benefits of MIS pyeloplasty compared to OP to surgically treat UPJO in children <1 year of age.

MATERIALS AND METHODS

A systematic review was independently performed by two authors. Papers comparing both techniques (MIS pyeloplasty vs. OP) in infants were included in the meta-analysis. Data (mean ± DS or percentage) were analyzed using Rev.Man 5.4 A p < 0.05 was considered significant.

RESULTS

Nine studies (eight retrospective and one prospective) meet the inclusion criteria. A total of 3,145 pyeloplasties have been included, with 2,859 (90.9%) OP and 286 (9.1%) MIS. Age at operation was 4.9 ± 1.4 months in OP vs. 5.8 ± 2.2 months in MIS, p = ns. Weight at surgery was 6.4 ± 1.4 kg in OP vs. 6.9 ± 1.4 kg in MIS, p = ns. Operative time was 129.4 ± 24.1 min for OP vs. 144.0 ± 32.3 min for MIS, p < 0.001. LOS was 3.2 ± 1.9 days for OP vs. 2.2 ± 0.9 days for MIS, p < 0.01. Postoperative complications were present in 10.0 ± 12.9% of OP vs. 10.9 ± 11.6% in MIS, p = ns. Failure of surgery was 5.2 ± 3.5% for OP vs. 4.2 ± 3.3% for MIS, p = ns.

CONCLUSION

The development of miniaturized instruments and technical modifications has made MIS feasible and safe in infants and small children. MIS presented a longer operative time than OP. However, MIS seemed effective for treating UPJO in infants, showing shortened LOS compared to OP. No differences have been reported with regard to the incidence of postoperative complications and failure of pyeloplasty. Given the low quality of evidence of the meta-analysis according to the GRADE methodology, we would suggest limiting MIS procedures in infants to only those high-volume centers with experienced surgeons.

Minimal Invasive Treatment in Pelvic-Ureteric Junction Obstruction: A Comprehensive Review

Pelvic-ureteric junction obstruction (PUJO) is a common condition, and one of the lead causes of hydronephrosis in children. Currently, the gold standard treatment of PUJO is open surgery using the Anderson–Hynes-modified dismembered pyeloplasty technique. However, with the advancement of medical technology, several minimal invasive approaches were developed, including endoscopic, laparoscopic, and robotic approach, from which the best choice of surgical technique was yet to be determined. Considering the advantages and disadvantages of these methods, the recommended option is to tailor the best surgical approach to each individual patient, and to the surgeons’ preference and experience. Considering these recent advances, a new algorithm is proposed to choose the best minimal invasive modalities invasive treatment to treat PUJO.

Functional outcomes of pediatric laparoscopic pyeloplasty: post-operative functional recovery is superior in infants compared to older children

AIM

Laparoscopic pyeloplasty (LP) is less popular and considered less successful in infants compared to older children. There are few reports analyzing the functional results of LP in relation to age of surgery. The aim of this paper is to compare the functional results of LP in infants (group 1) with children over 1 year of age (group 2).

MATERIAL AND METHODS

The data of all children undergoing LP between August 2016 and July 2019 were retrospectively analyzed for patient details and follow-up. Only children (n = 135) with at least 1-year follow-up and completed post-operative ultrasound and diuretic renogram were included. All children underwent pre-operative and post-operative ultrasound and diuretic renogram; pre-operative, operative and post-operative parameters were compared between both groups. Statistical analysis was done using software; Mann-Whitney U test, Student t test, and Fisher's exact test were applied.

RESULTS

There were 71 infants (group 1) and 64 children > 1 year (group 2). Pre-operatively, all kidneys had SFU grade 3 or 4 HDN and 131/135 kidneys had a renal pelvic APD > 20 mm; all kidneys had unequivocal obstruction on DR. At surgery, the preferred drainage method was intra-operative antegrade placement of a JJ stent in 68 (96%) group 1 and 63 (98%) group 2 children. The remaining 4 cases (3 group 1, 1 group 2) had a nephrostomy with trans-anastomotic external stent placement, because the JJ stent could not be negotiated into the bladder. The demographic data and comparison of pre- and post-operative parameters between both groups are summarized in Tables 1 and 2, respectively. Group 1 had significantly more children with antenatal diagnosis of HDN (87% vs 56%, p = 0.0005). The 36 children with antenatal diagnosis in group 2 were initially followed expectantly; the indication for pyeloplasty was deterioration of SRF on serial DR, urinary infection, and pain, in 13, 14, and 9 children, respectively. The operating time was significantly longer in group 2 (p = 0.0001). There was no difference in the success of LP or complication rate in both groups. Group 2 had significantly more children with extrinsic obstruction (1.4% vs 17%, p = 0.001). All children underwent post-operative US and DR; a significant reduction in hydronephrosis (APD) on follow-up was noted in both groups (p = 0.0001). The mean pre-operative SRF in both groups was comparable (p = 0.088). The mean SRF in both groups improved significantly after LP; however, the mean post-operative SRF was significantly higher in group 1 when compared to group 2 (p = 0.0001). Furthermore, group 1 had significantly more kidneys demonstrating > 10% increase in SRF after LP (53% vs 26%, p = 0.0003).

CONCLUSIONS

The safety profile and success of LP in infants was comparable to older children. Infant LP took shorter time to perform, while older children had increased incidence of extrinsic obstruction. Infant kidneys demonstrated better functional improvement than older children after LP. These findings should encourage more surgeons to utilize LP for pyeloplasty even in infants.

A systematic review and meta-analysis of conventional laparoscopic versus robot-assisted laparoscopic pyeloplasty in infants

OBJECTIVE

While there are several reports confirming the safety and efficacy of laparoscopic pyeloplasty (LP) and robot-assisted laparoscopic pyeloplasty (RALP) in children there have been none comparing LP and RALP specifically in infants. In this meta-analysis, we have compared the outcomes of LP and RALP in infants.

METHODS

Pubmed (Medline), Publon, Index Medicus and Embase were searched using the search terms: pyeloplasty (laparoscopic OR robot-assisted) AND (infant), to identify all papers pertaining to LP and RALP. Systematic review was performed to identify information regarding number of patients/renal units, age, body weight, operating time, hospital stay, success and complications. Meta-analysis of heterogeneity was reported with I2statistics. Once heterogeneity was found low, the pooled outcomes were compared with student's t test and Fishers exact test, wherever appropriate.

RESULTS

After screening a total of 267 articles, 18 articles were included (10 articles on LP, 7 on RALP, 1 reporting both), comprising 323 renal units for LP and 173 renal units for RALP. With low heterogeneity (I2: 0%) both groups were considered to have been conducted under similar conditions for fixed effect model. There was no significant difference between the success rates of LP or RALP (97.5% vs 94.8%; p = 0.21). The mean age at operation was significantly lower for LP (5.6 ± 1.8 months) than RALP (7.2 ± 1.2 months, P = 0.0001). The duration of surgery was 137 ± 45 min for LP while significantly higher at 179 ± 49 min for RALP (p = 0.0001). The mean (s.d) time to discharge was 2.0 (1.9) days for LP while 1.3 (0.4) days for RALP. The overall complication rate was significantly higher (summary table) for RALP than LP (p = 0.03), mainly due to more port-site hernias in RALP.

DISCUSSION

In the present study, we found that the success of LP and RALP in infants was similar. RALP in infants had longer duration of surgery, similar hospital stay and higher Clavien-3 complications than LP. While several studies have reported favorable outcomes for RALP over LP in children, this was not the case in infants. The smaller workspace, in an infant, can significantly limit the mobility of robotic instruments and increase the chance of port-site conflicts or trocar collisions. The use of larger robotic ports and instruments in the small space of infant abdomen might have been responsible for higher complications in RALP, including significantly larger number of port-site hernias. This meta-analysis represents the early experience of most RALP in infants, and it is possible that with experience RALP outcomes in infants also will catch up with LP. Miniaturization of robotic instruments might render RALP the future standard of care for pyeloplasty in infants.

Association between severity of prenatally diagnosed hydronephrosis and receipt of surgical intervention postnatally among patients seen at a fetal-maternal center

Background

Hydronephrosis (HN) is the most common abnormality detected on prenatal ultrasound. This study sought to stratify outcomes of patients by severity of prenatal HN with postnatal outcomes.

Methods

This was a retrospective review of patients referred to a tertiary care fetal-maternal clinic with diagnosis of prenatal HN from 2004 to 2019. HN severity was categorized as mild, moderate, or severe. Data were analyzed to determine the association between HN severity and surgical intervention. Decision for surgery was based on factors including history of multiple urinary tract infections, evidence of renal scarring, and/or reduced renal function. Surgery-free survival time was represented by the Kaplan–Meier method, and hazard ratios were calculated using the log-rank test.

Results

131 kidneys among 101 infants were prenatally diagnosed with hydronephrosis; 35.9% had mild HN, 29.0% had moderate HN, and 35.1% had severe HN. 8.5% of patients with mild HN, 26.3% of patients with moderate HN, and 65.2% of patients with severe HN required surgery. Patients with severe HN were 12.2 (95% CI 6.1–24.4; p < 0.001) times more likely to undergo surgery for HN than patients with mild HN and 2.9 (95% CI 1.5–5.3; p = 0.003) times more likely to undergo surgery than patients with moderate HN. Patients with moderate HN were 4.3 times more likely to require surgery than patients with mild HN (95% CI 1.5–12.9; p = 0.01). Median age at surgery was 11.8 months among patients with mild HN (IQR 11.7–14.1 months), 6.6 months among patients with moderate HN (IQR 4.2–16.4 months), and 5.4 months among patients with severe HN (3.7–12.4 months).

Conclusion

Among this cohort of referrals from a fetal-maternal clinic, severity of HN correlated with increased likelihood of surgical intervention. Continued assessment of patients with prenatal HN should be evaluated to best determine the role of the pediatric urologist in cases of prenatal HN.

Diminished Systemic Amino Acids Metabolome and Lipid Peroxidation in Ureteropelvic Junction Obstruction (UPJO) Infants Requiring Surgery

Congenital anomalies of the urinary tract, and particularly of obstructive nephropathy such as ureteropelvic junction obstruction (UPJO) in infants, can later lead to chronic kidney disease and hypertension. Fundamental questions regarding underlying mechanisms remain unanswered. The aim of the present study was to quantitate the systemic amino acids metabolome in 21 UPJO infants requiring surgery (Group A) and 21 UPJO infants under conservative treatment (Group B). Nineteen healthy age-matched infants served as controls (Group C). Serum amino acids involved in several pathways and representative metabolites, including the L-arginine-derived nitric oxide (NO) metabolites nitrite and nitrate and the lipid peroxidation biomarker malondialdehyde (MDA) were measured by gas chromatography–mass spectrometry (GC–MS) methods using their stable-isotope labeled analogs as internal standards after derivatization to their methyl esters N-pentafluoropropionic amides (amino acids) and to their pentafluorobenzyl derivatives (nitrite, nitrate, MDA). The concentrations of the majority of the biomarkers were found to be lower in Group A compared to Group B. Statistical analysis revealed clear differentiation between the examined study groups. Univariate statistical analysis highlighted serum homoarginine (q = 0.006), asymmetric dimethylarginine (q = 0.05) and malondialdehyde (q = 0.022) as potential biomarkers for UPJO infants requiring surgery. Group A also differed from Group B with respect to the diameter of the preoperative anterior–posterior renal pelvis (AP) as well as regarding the number and extent of inverse correlations between AP and the serum concentrations of the biomarkers. In Group A, but not in Group B, the AP diameter strongly correlated with hydroxy-proline (r = −0.746, p = 0.0002) and MDA (r = −0.754, p = 0.002). Our results indicate a diminished amino acids metabolome in the serum of UPJO infants requiring surgery comparing to a conservative group.

Meta-Analysis of the Efficacy of Laparoscopic Pyeloplasty for Ureteropelvic Junction Obstruction via Retroperitoneal and Transperitoneal Approaches

Objective: This study aimed to evaluate the clinical efficacy of laparoscopic pyeloplasty (LP) for ureteropelvic junction obstruction (UPJO) via retroperitoneal and transperitoneal approaches. Method: A systematic literature search on keywords was undertaken using PubMed, Cochrane Library, Embase, China Nation Knowledge (CNKI), and Wanfang. The eligible literature was screened according to inclusion and exclusion criteria. Meta-analysis was performed by using RevMan 5.0 software. Results: According to the inclusion and exclusion criteria, 12 studies were identified with a total of 777 patients. Four hundred eight patients were treated with retroperitoneal laparoscopic pyeloplasty (RLP), and 368 patients were treated with transperitoneal laparoscopic pyeloplasty (TLP). The meta-analysis results showed that the two approaches were similar in terms of presence of postoperative hospital stay, postoperative complication, the rate of conversion, and recurrence (p > 0.05). The operative time in the TLP group was significantly shorter than the RLP group (MD = 16.6; 95% CI, 3.40-29.80; p = 0.01). The duration of drainage was significantly shorter (MD = -1.06; 95% CI, -1.92 to -0.19; p = 0.02), and the score of postoperative visual analog score (VAS) was significantly lower in the RLP group than in the TLP group (MD = -0.52; 95% CI, -0.96 to -0.08; p = 0.02). Conclusion: Both approaches have good success rates and low postoperative complication rates. RLP provides a shorter duration of drainage and lower VAS score, but it takes more operative time than TLP.

Comparing Robot-Assisted Laparoscopic Pyeloplasty vs. Laparoscopic Pyeloplasty in Infants Aged 12 Months or Less

Objective: To investigate the outcomes of minimally invasive approach to infants with ureteropelvic junction (UPJ) obstruction by comparing the two surgical modalities of robot-assisted laparoscopic pyeloplasty (RALP) and laparoscopic pyeloplasty (LP). Methods: We conducted a retrospective review of all consecutive infants aged ≤12 months who underwent either LP or RALP in a single institution over the period of 2008-Jul 2020. We included primary pyeloplasty cases that were performed by or under the supervision of the same surgeon. Results: Forty-six infants (LP = 22; RALP = 24) were included with medians of age and body weight at 6 months (2-12months) and 8.0 kg (5.4-10 kg), respectively. There was no difference between the two groups in the patients' demographics and pre-operative characteristics. All infants underwent LP or RALP successfully without conversion to open surgery. None had intraoperative complications. Operative time (OT) was 242 min (SD = 59) in LP, compared with 225 min (SD = 39) of RALP (p = 0.25). Linear regression analysis showed a significant trend of decrease in OT with increasing case experience of RALP(p = 0.005). No difference was noted in the post-operative analgesic requirement. RALP was associated with a shorter hospital length of stay than LP (3 vs. 3.8 days; p = 0.009). 4/22(18%) LP and 3/24(13%) RALP developed post-operative complications (p = 0.59), mostly minor and stent-related. The success rates were 20/22 (91%) in LP and 23/24 (96%) in RALP (p = 0.49). Conclusions: Pyeloplasty by minimally invasive approach is safe and effective in the infant population. RALP may have superiority over LP in infants with its faster recovery and a more manageable learning curve to acquire the skills.