Urinary tract infections (UTIs) are the most common serious bacterial illnesses affecting young children. Nearly one in eight children with UTIs will develop permanent scarring in the kidneys. Worse, scarring is associated with a higher risk of kidney failure later in life. Unfortunately, the standard method of determining which children with UTIs that are at risk for renal or kidney scarring is quite invasive and delivers a considerable dose of ionizing radiation.

Researchers reported on Tuesday a set of criteria that are minimally invasive yet perform nearly as well as the standard method of assessing childhood UTIs and renal scarring risk. The criteria are high fever, detection of kidney abnormalities with ultrasound imaging, and detection of a non E. coli bacterial infection. Early detection of children who may develop scarring is crucial, and using the three criteria as a screening test will also allow doctors to set aside those children who will likely not develop scarring and avoid unnecessary procedures.

In the past, doctors used a catheter to deliver dye in the urinary system and then had the children urinate while undergoing X-ray imaging to detect alterations in the way the kidneys drained. The test causes considerable discomfort, delivers non-trivial amounts of radiation exposure, and is particularly unsettling to children.

Nader Shaikh and colleagues at the University of Pittsburg reviewed previously published studies involving 1,280 children and found the three criteria were most strongly associated with scarring. They constructed a predictive model and were able to positively identify 45 percent of the children that developed scarring. The test was even better at identifying those children who would not develop scarring, marking 80 percent of the low-risk group.

“The prediction is not perfect,” he said. “For more or less, we can say these 80 percent of kids aren’t going to scar, we don’t have to worry about them.”