Occurrence of vesicoureteral reflux among the antenatally detected urinary tract dilation/antenatal hydronephrosis

Background: Approximately 1% of pregnancies on obstetric ultrasound (US) are associated with structural fetal anomalies, among whom 20% are of the genitourinary system. Objective: The objective of this study was to determine the occurrence of vesicoureteral reflux (VUR) among the antenatally detected urinary tract dilation (UTD)/antenatal hydronephrosis (ANH) on postnatal follow-up. Methods: The study was a prospective observational study where the presence of anterior-posterior renal pelvis diameter (APRPD) of the fetal kidneys on obstetric ultrasound of >4 mm in the second trimester or >7 mm in the third trimester was taken to diagnose UTD/ANH were enrolled for the follow-up of successive US scans postnatally on the 7th, 30th, and 45th day of life. Patients with APRPD >4 mm postnatally, were subjected to micturating cystourethrogram (MCUG) at or after 45 days of life. Results: A total of 61,587 pregnant women visited the outpatient department, among whom 10,800 pregnant women underwent US scanning for fetal well-being during the second trimester, where 119/10,800 (1.1%) had UTD/ANH. A total of 21 patients were excluded from the study for various reasons and 98 patients were on follow-up. Postnatally on the 7th day of life, UTD/hydronephrosis (HDN) was detected in 41/98 (41.8%), as 57/98 (58.2%) neonates had no UTD/HDN. VUR was detected in 21/98 (21.4%) on MCUG. Conclusion: Around three-fifth of fetal UTD/ANH had a spontaneous resolution, whereas 2/5th has persistent UTD/HDN. Moderate and severe UTD/ANH infants possess a high risk of VUR as was observed in the present study and mandates a careful follow-up, to avoid any medical/surgical eventuality.