Is antibiotic prophylaxis necessary in infants with obstructive hydronephrosis?

PURPOSE: We investigated the relationship between the level of obstruction of the upper urinary tract and the risk and onset of urinary tract infection in infants with severe obstructive hydronephrosis to determine the need for antibiotic prophylaxis.

MATERIALS AND METHODS: A total of 105 patients were prenatally diagnosed with severe hydronephrosis (Society for Fetal Urology grade III or IV) due to upper urinary tract obstruction between 1994 and 2004. Of these patients 75 had ureteropelvic junction obstruction and 30 had lower ureteral obstruction. We retrospectively evaluated the clinical course and incidence of urinary tract infection during the first 12 months postnatally without antibiotic prophylaxis.

RESULTS: The incidence of overall urinary tract infection during followup was 36.2% (38 of 105 patients), and it demonstrated a higher trend with lower ureteral obstruction than with ureteropelvic junction obstruction (50% vs 30.7%, p=0.063). Most cases of urinary tract infection (92.8%) occurred before age 6 months, with a mean age at onset of 2.6 months. Of 105 patients 77 (73.3%) underwent corrective surgery at a mean age of 3.8 months. The incidence of urinary tract infection before surgical correction was 33.8% at a mean age of 2.1 months. The incidence of urinary tract infection in surgical cases was significantly higher with lower ureteral obstruction than with ureteropelvic junction obstruction (54.2% vs 24.5%, p=0.011).

CONCLUSIONS: Urinary tract infection in infants with severe obstructive hydronephrosis has a high incidence, occurs before age 6 months and is more common with lower ureteral obstruction than with ureteropelvic junction obstruction. These findings indicate that infants with severe hydronephrosis due to obstruction of the upper urinary tract should receive antibiotic prophylaxis.