BERKELEY, CA (UroToday.com) - Antenatal hydronephrosis (HN) is one of the most common congenital anomalies, seen in 1% to 5% of all pregnancies. Based on 2009 American Urological Association update and the 2010 Society for Fetal Urology (SFU) consensus statement on HN, it seems prudent to consider use of continuous antibiotic prophylaxis (CAP) in “high-risk” populations such as those with higher grade of HN.[1, 2, 3] Multiple prior reports have suggested that infants with moderate to severe HN are at higher risk of developing urinary tract infections (UTIs), thereby supporting the use of prophylactic measures.[3, 4, 5] However, recent studies have provided contradictory information, suggesting that infants with all grades of HN can be safely managed without CAP.[6, 7, 8]
Due to widespread use of routine prenatal ultrasound, the detection of fetuses with HN has increased proportionately. Management of patients with persistent HN after birth still remains controversial and is devoid of guidance based on high levels of evidence. Highlighting these issues, the 2009 Canadian Urological Association guidelines on antenatal HN stated that the role of CAP is indeed controversial and provided a grade D recommendation (based on case series and clinical experts’ opinion) for this specific topic. Our study was aimed at summarizing the current evidence in the literature spanning over 20 years to determine the importance of CAP the in prevention of UTIs in newborns with antenatal HN. Strict eligibility criteria for included studies have allowed us to gather a rather homogeneous population, summarizing information on relatively large numbers of infants identified antenatally and followed for a minimum of 12 months after birth. We considered SFU grades I and II and/or corresponding transverse renal pelvis APD ranging between 4.0 and 14.9mm on postnatal ultrasound as low-grade HN. SFU grades III or IV and/or transverse APD of renal pelvis ≥15.0mm on postnatal ultrasound were grouped into high-grade HN. UTI rates were significantly higher in infants with high-grade HN even when restricted to selected articles that reported a direct comparison of UTI rates between patients with low- versus high-grade HN within the same study.[3, 5, 6, 10, 11, 12] CAP in the high-grade group was associated with significant reduction of UTI rates when compared with no treatment (14.6% vs 28.9%; P<0.01). In contrast, UTI rates in infants with low-grade HN were similar regardless of CAP use. This core finding supports the notion of selective use of CAP for patients with high-grade HN. Due to paucity of data, we were unable to comment on the association between antenatal HN concurrent with VUR and UTI, and gender effect on UTI, adjusted according to HN grade. Associations between rate of UTI and isolated HN (uretero pelvic junction obstruction) or hydroureteronephrosis (primary megaureter) were often difficult to analyze because the included articles had not consistently provided UTI rates described according to etiology. In an attempt to assess UTI rates solely in patients with hydroureteronephrosis without VUR (primary megaureter), we saw that the pooled UTI rate was 34% (95% CI: 14-58), significantly higher than the rate of all patients with high-grade HN (23.3% (95% CI: 3.7-12)) suggesting that these patients might be at even higher risk of developing UTI and could benefit from administration of CAP.[3, 4, 5, 6]
The notable limitations of the review include the unavoidable restriction to observational studies as we could not identify any randomized controlled trials addressing the same problem. Even if all the included non-experimental studies were of high quality, the resultant level of evidence would be moderate at the most. Despite the limitations, we believe there is value in the current review. These findings are a first step toward tailoring our approach for patients with antenatal HN, which could be selectively favored in cases of high-grade HN.
- Nguyen HT, Herndon CD, Cooper C, et al. The Society for Fetal Urology consensus statement on the evaluation and management of antenatal hydronephrosis. J Pediatr Urol. 2010;6(3):212–231.
- Herndon ACD, Cain MP. Prenatal Diagnosis of Urological Disease. Vol. 28. Linthicum, MD: American Urological Association, Education and Research Inc; 2009:21–32.
- Song SH, Lee SB, Park YS, Kim KS. Is antibiotic prophylaxis necessary in infants with obstructive hydronephrosis? J Urol. 2007; 177(3):1098–1101.
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- Lee JH, Choi HS, Kim JK, et al. Nonrefluxing neonatal hydronephrosis and the risk of urinary tract infection. J Urol. 2008;179(4):1524–1528.
- Roth CC, Hubanks JM, Bright BC, et al. Occurrence of urinary tract infection in children with significant upper urinary tract obstruction. Urology. 2009;73(1):74–78.
- Greenfield SP. Antibiotic prophylaxis in pediatric urology: an update. Curr Urol Rep 2011;12(2):126–131.
- Islek A, Güven AG, Koyun M, Akman S, Alimoglu E. Probability of urinary tract infection in infants with ureteropelvic junction obstruction: is antibacterial prophylaxis really needed? Pediatr Nephrol. 2011;26(10):1837–1841.
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- Brophy MM, Austin PF, Yan Y, Coplen DE. Vesicoureteral reflux and clinical outcomes in infants with prenatally detected hydronephrosis. J Urol. 2002;168(4 pt 2):1716–1719.
- Wollenberg A, Neuhaus TJ, Willi UV, Wisser J. Outcome of fetal renal pelvic dilatation diagnosed during the third trimester. Ultrasound Obstet Gynecol. 2005;25(5):483–488.
- de Kort EH, Bambang Oetomo S, Zegers SH. The long-term outcome of antenatal hydronephrosis up to 15 millimetres justifies a noninvasive postnatal follow-up. Acta Paediatr. 2008;97(6):708–713.
Rahul K. Bansal, MBBS, MS, MCh and Luis H. Braga, MD, MSc, PhD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
McMaster University, Hamilton, Ontario, Canada