Research by a physician at Children's Hospital in Minneapolis is offering a new solution to a common problem in pediatric care: sorting out the many patients with bad stomachaches from the few who need surgery for appendicitis.

After studying a large group of children with belly pain, Dr. Anupam Kharbanda and colleagues reported Tuesday that white blood cell counts and other demographic details can distinguish many of those who are at high risk of appendicitis from those at low risk.

If follow-up research validates the approach, Kharbanda said, it could cut medical costs, reduce unnecessary imaging scans, and prevent mistaken operations that remove healthy appendixes.

The test could help doctors with a diagnostic challenge.

"Kids aren't always verbal ... when they come into the emergency room with belly pain," Kharbanda said.

It's an important dilemma, considering that belly pain accounts for one in 10 visits to pediatric emergency rooms across the country. Children's, for example, sees 10,000 belly pain patients at its ERs in the Twin Cities each year. Only around 900 have appendicitis.

The appendix is a mostly pointless sac on the lower right abdomen, but appendicitis results in inflammation that can lead to severe complications if the sac ruptures.

The solution has long been increasing use of CT scans, but they are expensive and expose patients to radiation. As an alternative, doctors in England developed a test called the Pediatric Appendicitis Score (PAS), but Kharbanda said it left most children in the middle-risk category for appendicitis, which left doctors having to order CT scans or ultrasounds anyway.

"That was the test we were trying to avoid in the first place," said Kharbanda, who is chief of critical care services for Children's.

Collaborating with doctors from HealthPartners in Bloomington and Kaiser Permanente in Oakland, Calif., Kharbanda looked back at the records of 2,400 children who were previously assessed for belly pain, hoping to identify the clinical features that separated those who had appendicitis. White blood cell counts, which reflect infection levels, turned out to be predictive, along with signs such as pain during walking.

Researchers then applied these criteria to a second group of 1,400 patients who were previously seen in ERs for belly pain. The approach placed nearly 50 percent of these patients into either the high- or low-risk groups for appendicitis — an improvement over the PAS, which sorted only 23 percent of patients into these risk groups.

Most important, the test was fairly accurate. In general, doctors accept that 3 to 5 percent of appendectomies end up removing healthy appendixes, said Dr. Elyse Kharbanda, a HealthPartners researcher who co-authored the study. (The Kharbandas are husband and wife.) But among those placed in the highest risk group by the new test, medical records showed that only 1.2 percent had gone on to have unnecessary surgeries.

The test is being designed as a front-line screen that would rule patients out or refer them for further testing before surgery. However, there is also debate within pediatrics about whether surgery is always needed even when a patient does have appendicitis, and whether antibiotic drugs alone could be used in some cases.

Finnish research in 2015 suggested that as many as 80 percent of appendectomies — the milder cases — could be treated without surgery. University of Washington doctors are leading a study in eight states to verify that result.

Kharbanda said he is skeptical that antibiotics can replace appendectomies, which are simple surgeries with low complication rates. Some patients treated with drugs ended up relapsing, he said.

The next step for Kharbanda is a clinical trial, already underway at 17 U.S. hospitals, to try the test on new patients arriving in ERs with complaints of belly pain.

Over time, he said he hopes that more data on patients can sharpen the test so it can predict risk level and perhaps suggest which patients need surgery vs. medication only.

A reliable test might also even out racial disparities in the way appendicitis is treated, he added. Studies have found differences by race in how patients' appendicitis pains are managed and in how many patients suffer complications after surgery.

"If you look across the country," he said, "how you are treated depends on where you end up and the clinician you see."

Jeremy Olson • 612-673-7744