University of Michigan
Department of Pediatrics
Evidence-Based Pediatrics Web Site

Question

• Does the timing of VCUG significantly affect the results to warrant placing a child with a first symptomatic UTI on prophylactic antibiotics for 4-6 weeks until vesicoureteral reflux can be ruled out?

Clinical Bottom Lines

1. There are no human studies to support the teaching that urine infection with inflammation surrounding the vesicoureteric junction will cause transient vesicoureteral reflux, or increase the severity of the baseline vesicoureteral reflux; and, therefore, it has not been established that performing the VCUG 4-6 weeks after first symptomatic UTI will prevent false positives necessitating long term uroprophylaxis.
2. In pediatric patients grouped according to the timing of the VCUG's, there was no evidence of an association between the timing of the VCUG after urinary tract infection and vesicoureteral reflux (chi squared = 0.58, p = 0.5: odds ratio 0.93, 95% confidence interval 0.76 to 1.12).¹
3. There was found only to be a weak association between timing of the VCUG and grade of vesicoureteral reflux (p = 0.04) due to two cases of grade III-V vesicoureteral reflux in children who had the VCUG performed within the first week after diagnosis.

Summary of Key Evidence

1. Cross sectional analytical study that breaks the patients down into groups according to the timing of their follow-up VCUG studies after first symptomatic UTI.  The timing of the VCUG for each patient was dependent on appointment availability, and convenience to coincide with real ultrasonagraphy.  All VCUG's were performed within 6 weeks after diagnosis of UTI.
2. The sample population included 272 children under 5 years of age who presented to the Royal Alexandra Hospital for Children's emergency department between March, 1993 and December, 1994 with a symptomatic urinary tract infection.  They were identified prospectively through the hospital lab with guidelines for diagnosis of >10⁶ CFU from a suprapubic or catheter specimen, or >10⁷ CFU from a clean catch specimen.  Children with a previous history of UTI or known renal, neurological, or skeletal predisposing causes were excluded.
3. Participants were either on treatment or prophylactic doses of antibiotics at the time of testing.
4. An initial history and physical exam were performed by the same physician on all of the participants.
5. All VCUG's were read by one of two pediatric radiologists and graded using the standards set by the international study of reflux in children.  The radiologists were blinded in regards to the timing of the VCUG relative to the diagnosis of UTI.

Additional Comments

• Ideally, a study would compare VCUG's performed on the same children at <4-6 weeks after positive urine culture, and >4-6 weeks after the positive culture in order to create a comparison to a "gold" standard to prove whether or not timing of the VCUG makes a difference in detection of vesicoureteral reflux.  However, due to the invasive nature of the VCUG, that was not deemed feasible by the authors of this study.
• The children in this study who had the VCUG within one week after diagnosis were more likely to show vesicoureteral reflux, and of a higher grade, but this result is difficult to interpret due to the exceedingly small sample size.  These results show that beyond one week after diagnosis of UTI, there is no evidence of an association between the presence or grade of reflux and the timing of VCUG.
• Deferring VCUG for 4-6 weeks after starting antibiotic therapy may cause undo parental anxiety surrounding the uncertainty of the diagnosis, and the child will have to remain on prophylactic antibiotics until the test is performed.  There is also the potential for increased compliance if the test can be scheduled earlier in conjunction with the renal imaging studies.

Citation

1. Author. Vesicoureteric Reflux and Timing of Micturating Cystourethography after Urinary Tract Infection.  Archives of Disease in Childhood, 76(3), 1997.
2. See also the role of ultrasound in the diagnosis of VUR.

CAT Author: Kari Baum, MD

CAT Appraisers: John Frohna, MD

Date appraised: January 18, 1999