Question

• Is an ultrasound a sufficient study in the evaluation of UTI, if reflux is the main concern?

Clinical Bottom Lines

1. Renal ultrasound is important in the evaluation of the anatomical structure of the kidney; however, VCUG is a more sensitive test to rule out vesicoureteral reflux.
2. In evaluating a child for recurrent UTI, both procedures must be obtained.

Summary of Key Evidence

1. 1993 study performed at U of M¹, evaluated records of children who had imaging studies of their kidneys for various reasons.  Evaluated 3000 records, identified 493 children ages 1 week - 19 years who had ultrasound and VCUG on the same day.  Each kidney considered separately for total of 986 kidneys.
2. Exclusions were children with myelomeningocele, and history of renal surgery.
3. Of 986, 272 (34%) of the kidneys evaluated were found to have reflux.
4. Of 272 kidneys with reflux, 201 (74% ) were normal on ultrasound. 102 of these normal ultrasounds were in children under 4 years-old.  This gives a sensitivity of only 26%.
5. The authors point out that 28% of the missed refluxing kidneys had grade III or higher reflux.¹

Additional Comments

• Ultrasound is a good method for screening or evaluating the kidney for structural abnormalities: differences in size, hydronephrosis, scarring, and cystic changes.
• If reflux is the concern, VCUG is the best test to perform.
• Recommendations at this institution are:
  • Ultrasound and VCUG should be done in initial evaluation of a recurrent UTI.  In infants, after first UTI, VCUG should be obtained 6 weeks after completion of treatment.
  • Continue prophylaxis until results of VCUG obtained.
  • If reflux is present, continue prophylaxis until reflux is resolved.

Citation

1. Blane CE, DiPietro MA, Zerin JM, Sedman AB, Bloom DA.  Renal sonography is not a reliable screening examination for vesicoureteral reflux.  J Urology 1993;150:752-755.
2. DiPietro MA, Blane CE, Zerin JM.  Vesicoureteral reflux in older children:  Concordance of US and voiding cystourethrographic findings.  Radiology 1997; 205:821-822.
3. Garin EH, Campos A, Homsy Y.  Primary vesicoureteral reflux:  Review of current concepts.  Pediatric Nephrology 1998; 12:249-256.
4. Rushton GH, et al.  Urinary tract infections in children.  Pediatric Clinics of North America, 1997; 33(5):1133-1169.
5. Sreenarasimhaiah S and Hellerstein S.  Urinary tract infections per se do not cause end-stage kidney disease.  Pediatric Nephrology 1998; 12:210-213.

CAT Author: Sandra Cadichon, MD

CAT Appraisers: <Reviewers>, MD

Date appraised: August 24, 1998