'Congenital' hydronephrosis: limitations of diagnosis by fetal ultrasonography.

Objective: To determine whether children presenting clinically with pelvi-ureteric junction obstruction had fetal hydronephrosis.

Patients And Methods: Forty-three children, born during or after 1985, presented clinically with pelvi-ureteric junction obstruction. Records of the maternal pregnancies were reviewed with reference to the findings of any fetal ultrasonography.

Results: In 25 patients fetal ultrasonography was performed at or beyond 30 weeks' gestation (mean 33.2). None had significant fetal hydronephrosis.

Conclusion: Hydronephrosis due to pelvi-ureteric obstruction is not necessarily congenital and patients presenting clinically may differ inherently from those detected fetally.