SUMMARY
Hydronephrosis is enlargement of renal collecting system including renal calyces with or without ureters. It is the most common prenatal anomaly and accounts for about 30–50% prenatal ultrasonography anomalies. Urinary tract dilation occurs in 1/100 pregnancies (1%) and causes significant uropathy in 1/500 (0.2%) cases. Antenatal hydronephrosis means dilation of the fetal renal collecting system that could be detected on prenatal ultrasonography and the prevalence is between 0.5% and 4%. Outcome depends on the underlying etiology. The index case was prenatally discovered at a gestational age of 6 months and postnatal assessment revealed a Grade V hydronephrosis with the absence of excretion or function on the right side.