Nonrefluxing neonatal hydronephrosis and the risk of urinary tract infection

The aim of this study was to assess the relationship between prenatally diagnosed nonrefluxing hydronephrosis and urinary tract infection.

We reviewed patients who were born at our institution between March 1989 and February 2006. Those who were diagnosed with fetal hydronephrosis confirmed on postnatal sonography were enrolled in the study. Hydronephrosis was graded according to the Society for Fetal Urology classification. Obstructive uropathy was diagnosed with (99m)technetium mercaptoacetyltriglycine renal scan and clinical courses. Voiding cystourethrography was done to exclude patients with vesicoureteral reflux. The prevalence of urinary tract infection was checked at 1-year followup.

A total of 430 patients without reflux were enrolled in the study. Male-to-female ratio was 351:79. Urinary tract infection developed in 83 patients (19%), with first infection occurring at age 4.1 +/- 2.7 months overall and before age 6 months in 70 patients (84% of subgroup). Frequency of urinary tract infection was 1.4 +/- 0.7 (range 1 to 4) episodes during the first year. Urinary tract infection developed in 50 of 128 patients with obstructive uropathy (39%), compared to 33 of 302 patients without obstructive uropathy (11%, p <0.001). High grade hydronephrosis was associated with an increased incidence of urinary tract infection-38 of 96 patients (40%) with grade IV hydronephrosis had urinary tract infection, compared to 26 of 79 (33%) with grade III, 13 of 94 (14%) with grade II and 6 of 161 (4%) with grade I disease (p <0.001). Urinary tract infection occurred more frequently in patients with vs without hydroureter (37 of 78, or 47%, vs 46 of 352, or 13%; p <0.001).

Neonates with obstructive uropathy, severe hydronephrosis or hydroureteronephrosis have increased risk of urinary tract infection even without reflux, and antibiotic prophylaxis may be recommended.