Projects

Abstract

Renal histologic changes in congenital ureteropelvic junction obstruction (UPJO), although well documented, are sparsely studied in children. This study aims to establish a histological grading depending on the glomerular and tubulo-interstitial changes in hydronephrotic kidneys and determine correlation with age at surgery and impact on function post-pyeloplasty. A renal cortical wedge biopsy was obtained after pyeloplasty and histological changes were graded from 1 to 4. A total of 47 viable biopsies from 57 children showed grade 1 changes in 10, grade 2 in 7, grade 3 in 27, and grade 4 in 3. Age at surgery, histological grade, and changes in differential renal function (DRF) were statistically analyzed. Younger age, near normal histology, and those with changes in 1 domain had preserved DRF pre-operatively. Renal histology and overall grade showed positive correlation with pre-operative DRF. However, no statistically significant association was noted with age at surgery or change in post-operative DRF. Introduction

Congenital ureteropelvic junction obstruction (UPJO) affects approximately 1:1000 to 2000 live births, occurring twice commonly in males than females. Routine ultrasound detects 30% to 50% of the patients antenatally, whereas the rest present with various symptoms in childhood.1 Studies have documented correlation between renal function and changes in renal biopsy at pyeloplasty in an attempt to predict post-operative renal function recovery. However, there are very few studies in children which highlight age-related histological changes in hydronephrosis secondary to UPJO and its effect on post-operative renal functional improvement. This study hence intends to analyze the renal histopathological changes in children with UPJO and note its association with age and differential renal function (DRF) of the affected kidney.

Materials and Methods

This is a prospective study over 2 years including children from 1 month to 7 years of age, with unilateral or bilateral intrinsic UPJO proven by an ethylene di-cysteine (EC) renogram. Patients with secondary UPJO and those with associated anomalies like horse shoe kidney, ectopic kidney, or vesicoureteral reflux with UPJO were excluded. An informed consent was obtained from the parents for procuring renal biopsy following pyeloplasty. The study was approved by the Institutional Ethics Committee, SJMC 243/2018 (The study activity was temporarily suspended due to COVID 19 and resumed after the pandemic.). Objectives of the study were (1) to establish a histological grading depending on the glomerular and tubulo-interstitial changes in hydronephrotic kidneys with UPJO and (2) study the correlation between histological changes and age at surgery and note whether the histological changes dictate functional recovery post-pyeloplasty.

After pyeloplasty, a renal cortical wedge biopsy from the lateral border of the kidney at the junction of middle and lower third was taken. A 5 μ sections of formalin-fixed paraffin-embedded tissue was Hematoxylin & Eosin stained and studied. Masson’s trichrome stain was used to assess the interstitial fibrosis. Changes in the glomeruli, tubules, and interstitium were studied and graded as below. The specimen was analyzed by a single pathologist. The biopsy findings were collated along with patient demographics. The changes in the biopsy specimens were analyzed and graded as below. Post-operative follow-up for a minimum of 6 months was documented.