Postnatal diagnosis and outcome of urinary tract abnormalities detected by antenatal ultrasound.

OBJECTIVES

To determine the incidence of urinary tract abnormalities detected by antenatal ultrasound; the value of fetal renal measurements in predicting significant uropathy; and the nature and clinical outcome of fetal uropathy.

DESIGN AND SETTING

A retrospective analysis of babies with urinary tract abnormalities detected before birth who were born at or referred to a teaching hospital.

PATIENTS

One hundred and twenty-five babies born between June 1989 and November 1992. Sixty-nine babies were born at Westmead hospital and 56 were born elsewhere and referred to Westmead Hospital for investigation.

RESULTS

The incidence of uropathy detected before birth among babies born at the teaching hospital was 5.1 per 1000 births. In 60% of these babies, significant abnormalities were confirmed after birth (3.1 per 1000 births). We found a significance of 71% and a specificity of 89% for fetal measurements in predicting significant uropathy. Among all 125 babies the most common abnormalities were pelviureteric junction (PUJ) anomalies (34%), minimal hydronephrosis (26%), ureteric reflux (18%) and multicystic kidney (7%). Pyeloplasty has been performed in 23 (46%) of the 52 kidneys with PUJ anomalies. Renal parenchymal abnormality was detected in four of 22 kidneys with ureteric reflux (18%). Of these four, all were exposed to Grade IV or V ureteric reflux but none had been infected.

CONCLUSIONS

Antenatal ultrasound is a sensitive, though nonspecific, tool for the non-invasive identification of congenital abnormalities of the urinary tract, which are common and frequently asymptomatic after birth. Although ureteric reflux may not be predicted from renal measurements, the degree of fetal hydronephrosis indicates the likelihood of obstructive abnormality and, thus, the extent of postnatal investigation required.