Postnatal outcomes of babies diagnosed with hydronephrosis in utero in a tertiary care centre in India over half a decade

Background: Prenatal hydronephrosis is defined as the dilatation of the fetal renal pelvis and/or calyces and is the commonest anomaly detected in utero. Methods: This was a retrospective study to look at how well 148 antenatally detected cases of fetal hydronephrosis correlated with postnatal evaluation. Results: Antenatal hydronephrosis was detected with a prevalence of 0.33%. The mean gestational age at diagnosis was 25.48 [standard deviation (SD) 6.36]. One hundred and sixteen (78.3%) fetuses had serial ultrasound scans during pregnancy to look for the progression of the condition. At the time of diagnosis, 30.1% of the fetuses were diagnosed to have mild hydronephrosis, 43.9% to have moderate hydronephrosis and 25.8% to have severe hydronephrosis. Follow-up ultrasounds during the prenatal period, 65% showed progression of the renal pelvis dilatation, 25.8% showed stable disease and 9.1% showed resolution on their subsequent scan. Almost half (46%) were found to have transient/physiological hydronephrosis. Thirty-one (20.9%) of the babies required an operation. An anteroposterior renal pelvis diameter (APD) of the fetal renal pelvis >= 17.5 mm can predict the need for surgery with a sensitivity of 70% and a specificity of 76.6%. Conclusion: Counselling and decisions must be based on a series of ultrasound scans rather than a single evaluation. We use a cut-off of 17.5 mm as an indicator of possible postnatal surgical intervention.