Antenatal hydronephrosis (HN) is a common congenital anomaly, occurring in 1% to 5% of all pregnancies. Continuous antibiotic prophylaxis (CAP) has been recommended for newborns with HN to reduce the rate of urinary tract infections (UTIs) during the first 2 years of life. With increasing concerns about bacterial antibiotic resistance and unknown long-term effects, the use of CAP in preventing UTIs is being challenged. This systematic review was undertaken to evaluate the impact of CAP on UTI rates in infants with antenatal HN.
MEDLINE, EMBASE, CINAHL, and CENTRAL databases were searched for studies that met eligibility criteria: primary diagnosis of antenatal HN; all subjects were aged younger than 2 years; interventions included CAP, no treatment, or both; reported rate of UTI and number of patients who had voiding cystourethrography; HN graded according to the Society for Fetal Urology classification or anteroposterior diameter of the renal pelvis; and published between 1990 and 2010. The primary outcome was development of UTI in infants with low-grade HN compared with those with high-grade HN. Secondary outcomes were occurrence of UTIs in patients with concomitant vesicoureteral reflux (VUR) versus no VUR and occurrence of a UTI in girls compared with boys.
Of 1681 relevant citations, 309 articles were reviewed, of which 21 (13 retrospective, 8 prospective) were included in the final analysis. All studies were observational and included a total of 3876 infants. Urinary tract infection rates in low-grade and high-grade HN were reported in 7 studies, for 2420 and 560 infants, respectively. The pooled UTI rate was 4.7% for low-grade HN compared with 23.3% for high-grade HN (P < 0.01). Urinary tract infection rates for infants receiving CAP were reported in 851 patients from 9 studies and in 8 studies (2370 infants) for those not receiving CAP. The pooled UTI rate for antenatal HN patients receiving CAP was 9.9%, similar to the 8.3% rate in infants not receiving CAP. The pooled UTI rates in patients with low-grade HN were 2.2% for infants on CAP and 2.8% for those not on CAP. In the high-grade HN group, infants on CAP had a UTI rate of 14.6% compared with 28.9% for those not on CAP, a significant difference. The pooled UTI rate for infants with VUR was 22.8% compared with the 9.3% for patients without VUR. Urinary tract infection rates were similar in boys (15%) and girls (18.9%) with antenatal HN. The pooled odds ratio (OR) was 5.8, suggesting that high-grade HN was significantly associated with higher rates of UTIs. The pooled OR for high-quality studies (6.3) also suggested that high-grade HN was significantly associated with higher UTI rates. In a meta-analysis of only studies that compared CAP use versus no CAP use, the pooled OR was 1.7, indicating that patients receiving CAP had significantly lower UTI rates.
The routine use of CAP has gained attention due to the perceived lack of clinically significant benefit in VUR trials and because of concerns for bacterial resistance and long-term adverse effects. The decision is based on risks/benefits, but consensus on what constitutes a risk for UTI warranting CAP use will be elusive until randomized controlled trials are conducted.
Department of Surgery (L.H.B., H.M., F.F., J.P., J.D.), McMaster University, Hamilton, Ontario, Canada; and Division of Urology (A.J.L.), Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada