Urinary tract infection in infants in spite of prenatal diagnosis of hydronephrosis.

The efficacy of preventing neonatal urinary infection in infants by diagnosing hydronephrosis in the fetus on obstetrical ultrasonography was studied. 426 infants had uroradiologic evaluation between 1984 and June 1991 because they had hydronephrosis detected in utero. Thirteen with posterior urethral valves were excluded. Of the remaining 413, 13 (3.1%) presented with urinary infection in the first 6 months of life. Ten of the 13 were boys and 7 were not circumcised. Eleven of the 13 infants less than 2 months old were formula-fed. The causes of hydronephrosis were reflux alone in 6, ureteropelvic junction obstruction in 6 (with coexisting ipsilateral reflux in 4), and primary megaureter in 1. Ultrasonography alone was insufficient to exclude reflux. Amoxicillin-resistant bacteria were the causative organisms in all 10 for whom bacteriology data was available. Four categories of management failure were identified: 1) failure of communication of the prenatal findings, 2) antibiotics not prescribed, 3) antibiotics prescribed but not administered, and 4) infection in spite of continuous antibiotic prophylaxis. Uncircumcised formula-fed male infants with reflux seemed to be at special risk for infection.