Purpose Antenatally detected urinary tract abnormalities (ADUTA) are increasingly recognized. Our aims were to determine the incidence and outcomes of antenatally diagnosed congenital hydronephrosis in a large cohort.
Methods We reviewed the records of 18,853 deliveries between January 2008 and December 2011 at King Abdulaziz University Hospital, Saudi Arabia. ADUTA were recorded and their postnatal medical records were reviewed for demographic and radiological data.
Results ADUTA were diagnosed in 327 fetuses (1.7%). The commonest pathology was congenital hydronephrosis (n=313, 95.7%). Cystic renal anomalies were reported in four babies (1.2%) and 10 children (3.1%) were reported to have other renal anomalies, including duplex kidneys or a single kidney. Two-hundred and forty babies with congenital hydronephrosis were followed-up. Hydronephrosis resolved in 99 children (41.2%) within 2 months of birth. Twenty-nine subjects had underlying renal anomalies (12.1%), including vesico-uretral reflux (n=12, 5%), pelvi-uretric junction obstruction (n=14, 5.8%) and posterior urethral valve (n=3, 1.25%). The best predictor for non-resolving congenital hydronephrosis and underlying anatomical abnormalities was the AP diameter on the first postnatal scan. A cut-off point of 5 mm was found to be 83% sensitive in predicting non-resolving hydronephrosis, while 7 mm was 88% sensitive and 10 mm was 94% sensitive.
Conclusion Congenital hydronephrosis is the commonest ADUTA. A large percentage resolved within 2 months of birth, but underlying anatomical abnormalities were found in 12.1%. All babies with antenatally detected hydronephrosis should be examined by US postnatally but further radiological investigations should only be performed for persistent significant AP dilatation ≥10 mm.