Imaging the urinary tract

Article Outline

• Copyright

The appropriate approach to imaging the urinary tract after a urinary tract infection (UTI) in childhood continues to be a moving target. Many texts and articles recommend an upper tract study with an ultrasound as well as an investigation of the lower tract with a voiding cystourethrogram (VCUG) after a first infection in a child of any age or sex. Others are more relaxed with their approach. There is little doubt that the likelihood of finding a major urinary tract anomaly after such investigation has dropped enormously now that most such anomalies are recognized by prenatal ultrasonography.

The current issue of The Journal contains two articles that attempt to provide guidance in selecting children for VCUG after UTI. Neither can be considered to be definitive, yet both are exciting work which may well change practice in the future.

Tseng et al in Taiwan reviewed 142 children who received renal cortical imaging (DMSA scans) as well as VCUGs following their first UTI. The results of the study were complex, but the take-home message is that a negative DMSA scan virtually always assured that no significant amount of vesicoureteral reflux was present. Although this observation is both interesting and not surprising, it then begs the question as to whether children with first UTIs should receive DMSA scans! Although the radiation exposure from a DMSA renal scan is less than that in a conventional VCUG, the test is quite a bit more expensive, and is certainly not an established standard of care in the United States.

Leroy and a group from several European centers asked whether determination of an acute phase reactant, serum procalcitonin (PCT), during first febrile UTI could select children at high risk for vesicoureteral reflux. Elevation in PCT at the time of infection had a sensitivity of 100% in identifying children with severe (grand 4 or above) reflux.

This is a story that is still being written. Practitioners should be familiar with studies such as these, not so much because of their immediate applicability to practice, but as indicators that this is a robust area of clinical investigation.