Prenatal diagnosis and perinatal urology

The kidney is formed by the interaction of the ureteric bud and metanephros during the fifth week of gestation and urine is excreted into the amniotic cavity from the ninth week onwards. The introduction of routine antenatal ultrasonography into obstetric practice has had a profound impact on the specialty of paediatric urology and the majority of urological abnormalities which pose a serious threat of morbidity are now detected prenatally. The results of foetal intervention to treat severe lower tract obstruction have been disappointing because renal damage (notably dysplasia) is largely irreversible by the time the anomaly is first identified. Indications for urgent postnatal evaluation include bilateral upper tract dilatation, thick-walled bladder, and impaired bladder emptying. A selective approach to the postnatal investigation of unilateral pelvic dilatation is required to avoid submitting healthy infants to unnecessary investigations.