Is a DMSA Scan Necessary for UTI in Children?

The classic teaching in the evaluation of children with febrile, culture-proven urinary tract infections (UTI) is to order a DMSA (dimercaptosuccinic acid) Scan to look for scarring of the kidney.  If the kidney is scarred, it indicates a serious infection that warrants treatment to prevent long-term damage to the kidney.

DMSA is injected intravenously, taken up by the kidney over the next two to four hours during which repeat imaging is taken.  It requires that child get an IV, stay in the hospital for a few hours, are often given general anesthesia, and has a small, but not negligible, radiation exposure.  Areas of decreased uptake on a DMSA Scan represent pyelonephritis or scarring. In a systematic review of 33 studies, approximately 60 percent of children with initial UTI had DMSA scans consistent with acute pyelonephritis in the acute phase of illness, but only 15 percent had renal scarring at follow-up [1].  Many children are given one or more repeat DMSA Scans as follow-up to monitor their infections.

Ming-Hsien Wang, MD, Assistant Professor of Pediatric Urology at the Brady Urological Institute at Johns Hopkins challenges the use of DMSA as a first-line study of children with UTI,

"A baseline ultrasound can tell you whether there's significant scar, and it can do so without exposing children to the side effects of a test that has minimal clinical benefit."

Dr. Wang and colleagues investigated 126 Johns Hopkins Children's Center patients (age 1 month to 5 years) and found that DMSA did not improve the diagnosis when ultrasound was used as the initial test to evaluate for renal scarring and infection.  This research will be presented at the upcoming American Urological Association (AUA) Annual Meeting in Orlando, Florida; and the European Society for Pediatric Urology (ESPU) Annual Meeting in Innsbruck, Austria.

Dr. Wang and colleagues see approximately 200 children each year with fever and culture-proven UTI.  "Our protocol for these children is baseline ultrasound, and we do not order a DMSA unless the ultrasound shows evidence of scar."  Dr. Wang is a co-principle investigator for an ongoing NIH study of UTI in children and is working to develop evidence-based clinical decision rules to improve diagnosis and avoid unnecessary tests in children.


Portions of this blog entry are extracted from "Rethinking the DMSA Scan" in the Johns Hopkins Urology Newsletter for Physicians.


[1] Shaikh N, Ewing AL, Bhatnagar S, Hoberman A.  Risk of renal scarring in children with a first urinary tract infection: a systematic review.  Pediatrics. 2010 Dec;126(6):1084-91. doi: 10.1542/peds.2010-0685. Epub 2010 Nov 8.