Predictive Factors of Contralateral Operation after Initial Pyeloplasty in Children with Antenatally Detected Bilateral Hydronephrosis Due to Ureteropelvic Junction Obstruction

The sequence of intervention determines the risk of early postoperative acute kidney injury in infants with bilateral ureteropelvic junction obstruction

INTRODUCTION AND OBJECTIVES

The management of bilateral ureteropelvic junction obstruction (UPJO) is greatly debated. We aim to identify the risk of early postoperative acute kidney injury (AKI) in relation to the sequence of intervention in children with bilateral UPJO managed in a sequential manner.

METHODS

A single center database was retrospectively reviewed for children ≤2 years who underwent bilateral pyeloplasty. According to the differential renal function on the preoperative renograms, patients were categorized into group A: pyeloplasty on the poorer functioning kidney first and group B: pyeloplasty on the better functioning side first. Serum creatinine and eGFR, using the modified Schwartz formula, were evaluated at four time points (I): before the first intervention (II): within 48 h of the first intervention (III): before the second intervention and (IV): within 48 h of the second intervention. Preoperative and postoperative values were compared. The incidence of early postoperative AKI in both groups was defined according to the Acute Kidney Injury Network (AKIN) criteria.

RESULTS

The study comprised 46 children treated by staged pyeloplasty, 28 of them underwent pyeloplasty on the poorer functioning side first. Baseline serum creatinine and eGFR were not significantly different between both groups. Patients who underwent pyeloplasty on the poorer functioning side first, had a significant decline of eGFR after the first intervention (p = 0.006). Conversely, no significant eGFR changes were observed after the first or second interventions in the other group (figure). Overall, 64.3% and 33.3% of patients developed some degrees of AKI when intervention was started on the poorer and better functioning renal units, respectively (p = 0.04).

DISCUSSION

Bilaterality is seen in approximately ¼ of patients with UPJO. Oftentimes, both renal units are asymmetrically affected with little data to guide surgeons on the optimal sequence of intervention. Following pyeloplasty, 52.2% of the evaluated children with bilateral UPJO had early postoperative AKI, mostly of low stage. Our data suggest that intervening first on the better functioning side allows for better recovery of the renal functional reserve and lowers the risk of postoperative AKI.

CONCLUSION

In children with bilateral UPJO, starting intervention on the poorer functioning kidney is associated with increased risk of postoperative AKI. Long-term prospective studies are needed to confirm our findings.

Postnatal management of bilateral Grade 3-4 ureteropelvic junction obstruction

Introduction:

Bilateral hydronephrosis on prenatal ultrasound can be managed expectantly or with surgical intervention. The treatment strategies and outcomes are not clearly defined.

Methods:

We conducted a retrospectively audit of outcomes of management of prenatally detected severe bilateral ureteropelvic junction obstruction (UPJO) in our institution.Patients with bilateral Grade 3–4 hydronephrosis were included. Those with complications like rupture, underwent bilateral intervention within 4 weeks; in the remaining, unilateral pyeloplasty was performed at 4–12 weeks. The contralateral renal unit was re-evaluated at a later date for further improvement or deterioration. All the patients were followed up with ultrasonography and renogram at 3 months, 6 months, and 1-year post operatively. The case records were analyzed for the resolution of antero-posterior diameter (APD) or the improvement in single-kidney glomerular filtration rate (s-GFR) in the operated units.

Results:

Over 15 years, 28 patients (56 renal units) had bilateral UPJO (male-to-female ratio = 13:1). Twelve units underwent neonatal intervention to tackle the complications (6 bilateral pyeloplasty), 17 units underwent early pyeloplasty, and 15 underwent late pyeloplasty. Twelve of the twenty-two (54%) contralateral units, which were stented/observed, resolved spontaneously. Receiver operating characteristics analysis revealed that those with initial APD <25 mm and initial s-GFR >35 ml/m were more likely to improve during the observation. Ten of the forty-four operated units (22%) failed to show an improvement. Units with initial s-GFR <10 ml/m had poor chance of postoperative functional recovery.

Conclusions:

In neonates with bilateral UPJO, the worse affected kidney is operated first, as it still has the potential to recover. The contralateral milder UPJO unit is known to recover spontaneously following unilateral pyeloplasty. In those with bilateral Grade 4 UPJO and mass, bilateral pyeloplasty is feasible. Alternatively, unilateral pyeloplasty + contralateral cystoscopic retrograde stenting may prevent rupture or functional deterioration in the opposite kidney.

Prenatal Diagnosis and Findings in Ureteropelvic Junction Type Hydronephrosis

The widespread use of obstetric ultrasonography has increased the detection rate of antenatal hydronephrosis. Although most cases of antenatal hydronephrosis are transient, one third persists and becomes clinically important. Ultrasound has made differential diagnosis possible to some extent. Ureteropelvic junction type hydronephrosis (UPJHN) is one of the most common cause of persistent fetal hydronephrosis and occurs three times more in male fetuses. It is usually sporadic and unilateral. However, when bilateral kidneys are involved and presents with severe hydronephrosis, the prognosis may be poor. Typical ultrasound findings of UPJHN is hydronephrosis without hydroureter. The size and appearance of the fetal bladder is usually normal without thickening of the bladder wall. Several grading systems are developed and increasingly being used to define the severity of prenatal hydronephrosis and provides much more information about prediction of postnatal renal prognosis. If fetal urinary tract dilation is detected; laterality, severity of hydronephrosis, echogenicity of the kidneys, presence of ureter dilation should be assessed. Bladder volume and emptying, sex of the fetus, amniotic fluid volume, and presence of associated malformations should be evaluated. Particularly the ultrasonographic signs of renal dysplasia, such as increased renal parenchymal echogenicity, thinning of the renal cortex, the presence of cortical cysts, and co-existing oligohydramnios should be noticed. Unfortunately, there is no reliable predictor of renal function in UPJHN cases. Unilateral hydronephrosis cases suggesting UPJHN are mostly followed up conservatively. However, the cases with bilateral involvement are still difficult to manage. Timing of delivery is also controversial.

Matrix Remodeling-Associated Protein 5 in Urinary Exosomes as a Potential Novel Marker of Obstructive Nephropathy in Children With Ureteropelvic Junction Obstruction

Recent investigations have described the use of urinary matrix remodeling-associated protein 5 (MXRA5) as a novel biomarker of kidney impairment in the setting of chronic kidney disease. In this study, we aimed to evaluate the possible clinical application of urinary MXRA5 as a useful non-invasive marker in the urine from the affected renal pelvis and bladder of children with ureteropelvic junction obstruction (UPJO). We conducted a prospective cohort study of patients aged <12 months with prenatally diagnosed unilateral UPJO who underwent dismembered pyeloplasty in 2018 or 2019, and a sex- and age-matched control group of healthy children. Blood urea nitrogen and creatinine levels were normal in all the patients. The whole urine and urinary exosomal concentrations of MXRA5 were measured by enzyme-linked immunosorbent assay. The correlations between bladder/renal pelvic MXRA5 levels and differential renal function (DRF) in the affected kidney were also determined. A total of 35 UPJO patients and 12 controls were enrolled in the study. There was no significant difference in whole-urine MXRA5 level between the controls and UPJO patients. However, the exosomal MXRA5 level was significantly lower in the controls than in patients with UPJO (p < 0.05). There were non-significant correlations between bladder and renal pelvis whole-urine MXRA5 levels and DRF (R ² = 0.1115, p = 0.05 and R ² = 0.3313, p = 0.0502, respectively). The strongest correlation was between exosomal MXRA5 level in the renal pelvis and DRF (R ² = 0.8128, p < 0.0001). Urinary exosomal MXRA5 level was significantly higher in children with UPJO than controls. Higher urinary exosomal MXRA5 levels were significantly correlated with lower DRF in the affected kidney in children with UPJO.

RBP and Alb in neonatal hydronephrosis and its association with IL-12 levels in pregnant women before delivery

Expression levels of retinol-binding protein (RBP) and albumin (Alb) in the kidney of patients with neonatal hydronephrosis were detected to explore whether RBP and Alb can be used as diagnostic indicators for neonatal hydronephrosis. Blood and urine samples from neonates with hydronephrosis in the obstetrics and gynaecology department of Hongqi Hospital Affiliated to Mudanjiang Medical University from January 2016 to January 2018, and healthy newborns were collected. RBP and Alb levels in neonates, and the expression of IL-12 in serum of the mothers were detected by ELISA. To establish the rat model, 30 male Sprague Dawley (SD) rats were randomly divided into two groups: sham operation group (n=15) and unilateral ureteral obstruction (UUO) (n=15). Expression of RBP and Alb protein was detected by western blot analysis. Another 30 female SD rats were randomly divided into the Sham and IL-12 knockdown groups. The Sham group was given NC treatment, while IL-12 knockdown group was given treatment with IL-12 knockdown adenovirus through tail vein injection. Results of ELISA showed that serum RBP and renal urinary Alb levels were higher in neonates with hydronephrosis compared with the control group (P=0.009 or P=0.013). Compared with the control group, levels of IL-12 were significantly lower in mother of neonatal hydronephrosis group (P=0.001). After the IL-12 knockdown treatment in pregnant rats, levels of RBP and Alb hydronephrosis-related indicators were significantly increased. The incidence of hydronephrosis in rats delivered via IL-12 knockdown pregnant rats was significantly higher than that of normal pregnant rats (P=0.001). The combination of RBP and Alb in the diagnosis of neonatal hydronephrosis has important clinical significance, and neonatal hydronephrosis is closely related to the level of IL-12 in mothers before birth. Our findings provide new ideas and theoretical basis for the diagnosis and prediction of neonatal hydronephrosis.