ANTENATAL DIAGNOSIS OF URINARY-TRACT ABNORMALITIES BY ULTRASONOGRAPHYAFTER 28 WEEKS GESTATION - INCIDENCE AND OUTCOME

OBJECTIVE: The objective was to establish the likelihood that antenata l upper urinary tract dilatation identified after 28 weeks of gestatio n will progress to significant postnatal uropathy. STUDY DESIGN: In 5 years, 3856 fetuses had ultrasonography after 28 weeks of gestation wh en the mothers were first seen in advanced pregnancy for delivery appo intments or for other obstetric indications. Fetuses with urinary trac t anomalies had ultrasonographic surveillance after 6 days and 6 weeks of life with further evaluation as necessary. RESULTS: Renal tract an omalies were identified in 313 fetuses, and 55 infants had significant renal tract abnormalities. There were 7 deaths; 2 infants were anephr ic and 5 with hydronephrosis had lethal congenital abnormalities. Dila tation of the upper urinary tract was identified in 7.7% of the fetuse s (298/3856) but was transient in 216 of them (72%). Follow-up of chil dren with transient renal pelvis dilatation found only one with a hist ory of urinary tract infection. Obstruction occurred in 23 infants (6. 0/1000) and 16 required surgical correction. Vesicoureteric reflux was identified in 14 infants (3.6/1000) and resolved by age 2 years in 64 %. Unilateral multicystic renal dysplasia occurred in 8 and posterior urethral valves occurred in 3 infants. CONCLUSION: Antenatal ultrasono graphy after 28 weeks' gestation identified significant renal tract ab normalities with a frequency of 14.3 per 1000 births, permitting early treatment of the asymptomatic newborn and reducing later renal damage .