Hydronephrosis severity score: an objective assessment of hydronephrosis severity in children-a preliminary report

Is cortical transit time a parameter to prove relief of obstruction after pyeloplasty in antenatally diagnosed ureteropelvic junction obstruction

PURPOSE

The study aims to determine the possible improvement in cortical transit time (CTT) after surgery in infants with antenatally diagnosed ureteropelvic junction obstruction (UPJO), and investigate the correlation of CTT with preoperative renal function and parenchymal thickness.

PATIENTS AND METHODS

Medical charts of 32 antenatally diagnosed children with UPJO operated on between 2014 and 2021 were reviewed. Patients' demographics, preoperative and postoperative anteroposterior diameter (APD), parenchymal thickness (PT) ratio, differential renal function (DF), drainage patterns and CTT were compared to determine operative benefit. Preoperative CTT of each patient was also grouped as severely delayed (> 6 min) and moderately delayed (3-5 min) and compared. The correlation between the preoperative CTT and preoperative DF and PT ratio was investigated.

RESULTS

The median age of the patients was 8.8 months (1-24 months). The CTT (mean: 6.8 ± 3.0 min) was prolonged before surgery and was significantly improved (mean 4.6 ± 1.0 min) after the operation (p < 0.001). A significant negative correlation was detected between the CTT and preoperative DF and between the CTT and preoperative PT ratio. Preoperative DF was found significantly impaired in patients within the severely prolonged CTT group compared to those within the moderately prolonged CTT group. Significant improvement in DF was detected in patients in the severely prolonged CTT group after surgery.

CONCLUSION

CTT is a parameter to prove relief of obstruction in patients with antenatally diagnosed UPJO after surgery. CTT is negatively correlated with preoperative DF and PT ratio. Severely prolonged CTT may be considered to be an indication of early surgical intervention.

Stratifying Antenatal Hydronephrosis: Predicting High-Grade VUR Using Ultrasound and Scintigraphy

(1) Background: Antenatal hydronephrosis (AHN), detected in approximately one percent of prenatal ultrasounds, is caused by vesicoureteral reflux (VUR) in 15-21% of cases, a condition with significant risks such as urinary tract infections and renal scarring. Our study addresses the diagnostic challenges of VUR in AHN. Utilizing renal ultrasonography and scintigraphy, we developed a novel scoring system that accurately predicts high-grade VUR, optimizing diagnostic precision while minimizing the need for more invasive methods like voiding cystourethrogram (VCUG); (2) Methods: This retrospective study re-analyzed renal ultrasonography, scintigraphy, and VCUG images from infants admitted between 2003 and 2013, excluding cases with complex urinary anomalies; (3) Results: Our analysis included 124 patients (75% male), of whom 11% had high-grade VUR. The multivariate analysis identified visible ureter, reduced renal length, and decreased differential renal function (DRF) as primary predictors. Consequently, we established a three-tier risk score, classifying patients into low, intermediate, and high-risk groups for high-grade VUR, with corresponding prevalences of 2.3%, 22.2%, and 75.0%. The scoring system demonstrated 86% sensitivity and 79% specificity; (4) Conclusions: Our scoring system, focusing on objective parameters of the visible ureter, renal length, and DRF, effectively identifies high-grade VUR in AHN patients. This method enhances diagnostics in ANH by reducing reliance on VCUG and facilitating more tailored and less invasive patient care.

Association of the Hydronephrosis Severity Score With Likelihood of Pyeloplasty: A Large Prospective Database Analysis

OBJECTIVE

To apply and reproduce this scoring system in our prenatal hydronephrosis population with ureteropelvic junction obstruction (UPJO)-like hydronephrosis (HN), specifically looking at determining better HHS cutoffs that would allow for stratification into three risk categories: spontaneous HN resolution, observation, and surgery.

METHODS

A prospectively collected prenatal hydronephrosis database was reviewed to extract UPJO-like HN patients. Children with vesicoureteral reflux, primary megaureter, bilateral HN, and other associated anomalies were excluded. Only patients who had an ultrasound and mercaptoacetyltriglycine renal scan at a minimum of 2-time points were included. Hydronephrosis Severity Score was calculated at the initial, interim, and last follow-up clinic visits. Scores were analyzed regarding its usefulness to determine which patients would have been more likely to undergo pyeloplasty.

RESULTS

Of 167 patients, 131 (78%) were male, 119 (71%) had left UPJO-like, and 113 (67%) had a pyeloplasty. The median age at baseline was 2months (interquartile range 1-4). According to initial (first clinic visit) Hydronephrosis Severity Score, 5/36 (14%) patients with a 0-4 score, 93/116 (80%) with a 5-8 score, and 15/15 (100%) with a 9-12 score underwent pyeloplasty, respectively (P < .01).

CONCLUSION

The proposed HHS system for UPJO-like HN patients is reproducible, however, cut-off values need to be reassessed to accurately reflect true risk categories, as the purpose of this system is to differentiate those who have HN severe enough to require intervention from those who can be managed nonsurgically. Changing risk groups to mild (0-3), moderate (4-6), and severe (7-12) allowed for better discrimination between patients who underwent surgical intervention from those who did not in our dataset.

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.

Severe Hydronephrosis Secondary to Ovarian Serous Carcinoma

This case study examines a patient with severe hydronephrosis caused by ureteral obstruction, secondary to ovarian serous carcinoma. Gynecologic malignancies, especially advanced ovarian carcinoma, are common extrinsic causes of obstructive hydronephrosis. Sonography is a valuable modality to visualize the kidneys, diagnose hydronephrosis, and determine the grade of hydronephrosis. The treatment of hydronephrosis aims to remove the build-up of urine, prevent permanent kidney damage, and treat the underlying cause. Prolonged or severe cases of hydronephrosis can lead to acute kidney injury.

Functional Magnetic Resonance Urography in Ureteropelvic Junction Obstruction: Proposal for a Pediatric Quantitative Score

BACKGROUND

Ureteropelvic junction obstruction (UPJO) is one of the most frequent causes of congenital hydronephrosis. It is essential to distinguish UPJO which needs surgical treatment. fMRU combines high quality morphological details of the kidney and excretory pathways with functional data.

OBJECTIVE

This study aims to introduce a new radiological score based on fMRU findings to be able to differentiate surgical from non-surgical kidneys.

MATERIALS AND METHODS

We retrospectively selected patients with hydronephrosis due to UPJO who underwent fMRU (January 2009-June 2018). A multidisciplinary team identified a list of fMRU morpho-functional predictive variables to be included in the analysis. To evaluate the role of different independent variables in predicting the outcome, a multivariable logistic regression model has been performed; the outcome variable was the surgical intervention. For each predictive variable, Odds Ratio and 95% Confidence Intervals were calculated. The likelihood ratio test was used to assess the significance of the variables. Using the regression model, we assigned a numerical value to each predictive variable, rounding up the beta-coefficients. The cut-off value of the total score was obtained from the ROC curve analysis.

RESULTS

A total of 192 patients were enrolled, corresponding to 200 pathological kidneys. All of them underwent fMRU; 135 were surgically treated, while 65 underwent ultrasound or MRU follow-up. Predictive variables significantly associated with surgery resulted to be the urographic phase, the presence of abnormal vessels, and a baseline anterior-posterior pelvic diameter >23 mm. Beta coefficients of the logistic regression model were then converted in scores. The ROC curve of the score showed high sensitivity (84.3%) and specificity (81.3%) with a cut-off > 2.5.

CONCLUSIONS

We propose a new fMRU score able to identify surgical vs. non-surgical kidneys with UPJO.

Treatment of infants with ureteropelvic junction obstruction: findings from the PURSUIT network

PURPOSE

Studies based on administrative databases show that infant pyeloplasty is associated with minority race/ethnicity but lack clinical data that may influence treatment. Our objective was to identify clinical and demographic factors associated with pyeloplasty in infants from three large tertiary centers.

METHODS

We reviewed infants with unilateral Society for Fetal Urology (SFU) grade 3-4 hydronephrosis seen at three tertiary centers from 2/1/2018 to 9/30/2019. Patients were excluded if > 6 months old or treated surgically prior to the initial visit. Outcomes were: pyeloplasty < age 1 year and SFU grade on most recent ultrasound (US) within the first year. Covariables included: age at the initial visit, race/ethnicity, treating site, insurance type, febrile UTI, and initial imaging findings. Univariable and multivariable analyses were performed using log-rank tests and Cox proportional hazards models, respectively.

RESULTS

197 patients met study criteria; 19.3% underwent pyeloplasty. Pyeloplasty was associated with: treating site (p = 0.03), SFU 4 on initial US (p = 0.001), MAG-3 (p < 0.001), and T½ > 20 min (p < 0.001) in patients undergoing a MAG-3 (n = 107). MAG-3 (p < 0.001) and location (p = 0.08) were associated with earlier time to pyeloplasty on multivariable Cox analysis. In infants with follow-up US (n = 115), initial SFU grade, MAG-3 evaluation or findings, and pyeloplasty were not associated with improvement of hydronephrosis.

CONCLUSIONS

We found that infant pyeloplasty rates vary between sites. Prolonged T½ was associated with surgery despite prior studies suggesting this is a poor predictor of worsening dilation or function. These findings suggest the need to standardize evaluation and indications for intervention in infants with suspected UPJ obstruction.

Ureteropelvic junction obstruction: diagnosis and management

PURPOSE OF REVIEW

Ureteropelvic junction obstruction (UPJO) is the most common cause of prenatally diagnosed hydronephrosis. Although associated with obstruction of the kidney, the natural history is variable, ranging from spontaneous resolution to progressive loss of function over the first few years of life. As a result, the optimal evaluation strategy and indications for treatment have not been well defined. The purpose of this article is to review recent literature focused on the prenatal and postnatal evaluation of infants with prenatally diagnosed hydronephrosis suspicious for UPJO.

RECENT FINDINGS

Recent studies have focused on the effect of the urinary tract dilation (UTD) ultrasound classification system, as well as use of magnetic resonance imaging both prenatally and postnatally to stratify the risk of infants with prenatally diagnosed hydronephrosis to develop renal impairment or undergo surgery. Additionally, urinary biomarkers have been identified as a potential noninvasive alternative to diuretic renography in identifying infants with clinically significant UPJO.

SUMMARY

Although continued work is needed to develop clear guidelines for evaluation and treatment and to better define long-term outcomes, these studies offer novel approaches to improve the care of these patients.

Uretero-Pelvic Junction Stenosis: Considerations on the Appropriate Timing of Correction Based on an Infant Population Treated with a Minimally-Invasive Technique

There is no univocal consensus about timing of intervention and best surgical approach for infants with asymptomatic uretero-pelvic junction obstruction (UPJO). We conducted a retrospective analysis of patients undergoing one-trocar-assisted pyeloplasty (OTAP) in a 13 year range period by creating two homogenous groups (indications for surgery were the same for all patients): patients operated on in the first 90 days of life (34 patients; Group 1) and patients operated on between 3 and 12 months of life (34 patients; Group 2). We observed no statistically significant differences between groups in regard to mean operative time, conversion rate to open surgery, mean hospital stay, early complications (urinary leakage) rate and mean antero-posterior diameter (APD) reduction rate. Moreover, no statistical improvement was seen between groups in regard to separate renal function (SRF) at 1-year-follow-up renogram. Thanks to the HSS calculated before and 1 year after surgery, we registered an important improvement in Group I patients (p = 0.023). In our study, there was no significant evidence, in terms of intraoperative data and early postoperative outcomes, between patients who underwent an early pyeloplasty and those who underwent a delayed correction. Nevertheless, we registered a significant improvement in those patients with an impaired SRF that underwent an early surgical correction, especially in terms of urinary flow. Even though this study cannot definitely establish the superiority of early timing of correction, it is evident that further research is needed to clarify this aspect.

Comparison of different pathological markers in predicting pyeloplasty outcomes in children

PURPOSE

To compare the efficacy of pathological markers like Interstitial cells of Cajal (ICC), neurons and Collagen to Muscle ratio (CM ratio), in predicting pyeloplasty outcomes.

METHODS

Histological sections from 31 patients with UPJO were analyzed for ICC & neurons on immuno-histochemistry and CM ratio on Masson's trichrome staining. Post-operative outcomes were analyzed at 1-year follow up; expressed as excellent, moderate or mild improvement, static and deterioration based on the three factors: ultrasound grade, differential renal function and renogram drainage pattern. The pathological findings were correlated with clinical outcomes.

RESULTS

The study group (n = 31) had a mean age 2.9 (0.6) years (M: F = 22:9). UPJ segment had significantly less ICC/neurons and more collagen compared to normal ureter (p = 0.001). Pathological parameters at the anastomosed end of ureter had a better correlation than those at UPJ with clinical outcome. CM ratio with a stronger correlation (r = - 0.94; p = 0.001) was a better predictor of prognosis than ICC (r = 0.76; p = 0.01) or neuron (r = 0.83; p = 0.01) density. ICC >10/HPF, neurons >6/HPF and CM ratio <1.2 at ureteric end anastomosed were predictors of success.

CONCLUSIONS

CM ratio analysis at anastomosed ureter is a superior marker for predicting pyeloplasty outcomes.

LEVEL OF EVIDENCE

Type 2: Development of diagnostic criteria in a consecutive series of patients.

Utility of ultrasound elastography in postoperative follow-up of children with unilateral ureteropelvic junction obstruction

Introduction:

We aimed to determine whether shear wave velocity (SWV) on ultrasound elastography is useful in follow-up of children with ureteropelvic junction obstruction (UPJO) following pyeloplasty.

Methods:

Consecutive children with unilateral UPJO who were co-operative for elastography (n = 31) were included. SWV of normal kidney was used as control, and it was compared with that of the affected kidney (UPJO) in the same patient. They were followed up with elastography at 3 months and elastography + renogram at 6 months postoperatively. In patients with a static renogram at 6 months, the study was repeated at 1 year. Patient outcomes were classified as improved at 6 months, static at 6 months, and worsened at 1 year based on ultrasound and renogram findings. The SWV was compared between the different outcomes.

Results:

Thirty-one children with a median age of 8.5 years were studied (m:f = 29:2; L:R = 22:9). The mean SWV was significantly higher (3.21 m/s) in UPJO kidney compared to the SWV (2.72 m/s) found in normal kidney (P = 0.011). The mean SWV was significantly less at 3 months (2.73 m/s) and 6 months (2.57 m/s) postoperative follow-up (P = 0.018 and P= 0.001). Among the patients who improved, the mean SWV was 2.65 m/s. This SWV was significantly raised (3.57 m/s) in patients whose condition remained static (P = 0.006) and even higher (4.36 m/s) in those who worsened (P = 0.001).

Conclusions:

SWV was significantly higher in UPJO compared to normal kidneys in children. It is useful in assessing postoperative resolution, and a rising velocity can be useful as an early marker of recurrence in UPJO.

Ultrasound-Based Scoring System for Indication of Pyeloplasty in Patients With UPJO-Like Hydronephrosis

Background: Previous scoring systems have used renal scan parameters to assess severity of ureteropelvic junction obstruction-like hydronephrosis (UPJO-like HN), however this information is not always reliable due to protocol variation across centers and renogram limitations. Therefore, we sought to evaluate the Pyeloplasty Prediction Score (PPS), which utilizes only baseline ultrasound measurements to predict the likelihood of pyeloplasty in infants with UPJO-like. Methods: PPS was developed using three ultrasound parameters, Society of Fetal Urology (SFU) grade, transverse anteroposterior (APD), and the absolute percentage difference of ipsilateral and contralateral renal lengths at baseline. PPS was evaluated using prospectively collected prenatal hydronephrosis data (n = 928) of patients with UPJO-HN. Children with vesicoureteral reflux. primary megaureter, other associated anomalies, bilateral HN and <3 months of follow-up were excluded. Scores were analyzed regarding its usefulness in predicting which patients would be more likely to undergo pyeloplasty. Sensitivity, specificity, likelihood ratios (LR) and receiver operating characteristic (ROC) curve were determined. Results: Of 353 patients, 275 (78%) were male, 268 (76%) had left UPJO-like HN, and 81 (23%) had a pyeloplasty. The median age at baseline was 3 months (IQR 1-5). The PPS system was highly accurate in distinguishing patients who underwent pyeloplasty using baseline ultrasound measurements (AUC: 0.902). PPS of 7 and 8 were found to have a sensitivity of 85 and 78%, and specificity of 81 and 90%, respectively. PPS of 8 was associated with a LR of 7.8, indicating that these patients were eight times more likely to undergo pyeloplasty. Conclusion: Overall, PPS could detect patients more likely to undergo pyeloplasty using baseline ultrasound measurements. Those with a PPS of eight or higher were eight times more likely to undergo pyeloplasty.

Grading of Hydronephrosis: An Ongoing Challenge

The crucial point for prompt diagnostics, ideal therapeutic approach, and follow-up of hydronephrosis associated with UPJ anomalies in children is the severity of hydronephrosis. Such many hydronephrosis grading systems as AP diameter, SFU, radiology, UTD, and Onen have been developed to evaluate hydronephrosis severity in infants. Unfortunately, it is still an ongoing challenge and there is no consensus between different disciplines. AP diameter is a very dynamic parameter and is affected by many factors (hydration, bladder filling, position, respiration). More importantly, its measurement is very variable and misleading due to different renal pelvic configurations. The radiology grading system has the same grades 1, 2, and 3 as the SFU grading system with addition of the AP diameter for the first 3 grades. This grading system divides parenchymal loss into two different grades. Grade 4 represents mild parenchymal loss while grade 5 suggests severe parenchymal loss. However, it is operator dependent, is not decisive, and does not differentiate grades 4 and 5 clearly. All grades of SFU are very variable between operators and clinicians. UTD classification aims to put all significant abnormal urinary findings together including the kidney, ureter, and bladder and thus determines the risk level for infants with any urinary disease. Different renal deterioration risks occur depending on the mechanism of hydronephrosis. Therefore, SFU and UTD classification may result in significant confusion and misleading in determining the severity of hydronephrosis. SFU-4 and UTD-P3 represent a considerable range of severity of hydronephrosis. Both represent minimal thinning of the medullary parenchyma and severe thinning of the cortical parenchyma (cyst-like hydronephrotic kidneys) at the same grade. The wide definition of SFU-4 and UTD-P3 fails to indicate accurately the severity of hydronephrosis and thus significantly misleads from a prompt treatment. They do not suggest who need surgical treatment and who can safely be followed non-operatively. The anatomy and physiology of the 4 suborgans of the kidney (renal pelvis, calices, medulla, and cortex) are completely different from each other. Therefore, each part of the kidney affect and behave differently as a response to UPJ-type hydronephrosis (UPJHN) depending on the severity of hydronephrosis. The upgraded Onen hydronephrosis grading system has been developed based on this basic evidence both for prenatal and post-natal periods. The Onen grading system determines specific detailed findings of significant renal damage, which clearly show and suggest who can safely be followed conservatively from who will need surgical intervention for UPJHN. Neither AP diameter nor radiology, SFU, or UTD classification is the gold standard in determining the severity of hydronephrosis. All these grading systems are based on subjective parameters and are affected by many factors. They do not determine the exact severity of UPJHN and thus cause permanent renal damage due to a delay in surgical decision in some infants while they may cause an unnecessary surgery in others. The Onen grading system has resolved all disadvantages of other grading systems and promises a safer follow-up and a prompt treatment for UPJHN. It is an accurate and easily reproducible grading that has high sensitivity and specificity.