The "Esophageal String Test": Doctors Create a New Type of Endoscopy

As far as diseases go, eosinophilic esophagitis (EoE) is pretty new — two decades ago, doctors didn’t even know it existed — and much mystery remains. But doctors do know what causes it: white blood cells called eosinophils, which, when concentrated in the esophagus, can cause chronic inflammation.

These cells are the hallmark of the disease, and the only way to assess whether eosinophils are there is by endoscopy and biopsy: an invasive and expensive test.

Something old, something new: Breaking barriers to care with a piece of string

Because some patients respond better to some treatments than others, gauging the relative presence of eosinophils is crucial not only to diagnose the disease, but also to measure the progress of treatment.

Endoscopy is a burden for patients, and Dr. Furuta’s team has made it a priority to find better ways to perform it. Children’s Colorado’s Joel Friedlander, D.O., pioneered a way to do endoscopies through the nose, avoiding the need for anesthesia. And our own Dr. Furuta came up with a way, in many cases, not to do them at all.

“There was an old test developed in the 70s,” Dr. Furuta says. “You had a capsule filled with string, and you would tape one end of the string to your cheek and swallow the capsule, and the string would go all the way down to the small intestine.” Doctors would then pull the string out and check for intestinal parasites. “We wondered if you could do a similar thing and check the portion of string from the esophagus for the unique proteins of eosinophils.”

Dr. Furuta’s team pioneers a new standard in testing

Measured against endoscopy, the results of the string test were “remarkably consistent” — enough so that Dr. Furuta’s team, with his collaborator Steven Ackerman, M.D., at the University of Illinois at Chicago, knew they’d produced a new treatment standard. With help from a grant and seed capital from Children’s Colorado, the team is developing a commercial version of the test, now undergoing trials, that it hopes to introduce to the market soon.

“We always try to identify the barriers to care for our patients,” says Dr. Furuta. “Can we use old approaches? Do we need to develop new ways to treat? The string test was kind of a combination of both.”

About Digestive Health research happening at Children’s Colorado

Our research and development team has developed a novel, low-cost, minimally invasive monitoring test for esophageal inflammation, the Esophageal String Test. We have also described a new mouse model of eosinophilic gastrointestinal (GI) disease that will be instrumental for understanding these diseases and testing new therapeutic approaches. Learn more about our GI research.

Read more from Dr. Furuta in the New England Journal of Medicine.