Introduction: When to Seek Diagnostic Testing
If you experience ongoing difficulty swallowing, especially with solid foods like meat or bread, or if you have heartburn that doesn’t improve with common acid-reducing medications, it may be time to talk to your doctor about testing for eosinophilic oesophagitis. This condition can affect people of all ages, from infants to older adults, and symptoms often vary depending on when the disease develops.[1]
Many people live with symptoms for years before receiving an accurate diagnosis because the signs of eosinophilic oesophagitis can resemble other, more common digestive problems. Young children might refuse to eat, vomit frequently, or fail to gain weight properly. School-age children often complain of recurring stomach pain or have trouble swallowing. Adults typically notice that food gets stuck in the throat or chest, which can be frightening and uncomfortable.[2]
You should consider diagnostic testing if you have experienced food getting stuck in your oesophagus, even once. This situation, called food impaction, can be a medical emergency because it may tear a hole in the oesophagus. Other warning signs include frequent vomiting, chest pain that doesn’t respond to antacids, or heartburn that persists despite taking proton pump inhibitors or other acid suppressors.[5]
People with other allergic conditions should be especially attentive to digestive symptoms. If you already have asthma, hay fever, eczema, or food allergies, your risk of developing eosinophilic oesophagitis is higher than in the general population. Having a family member with the condition also increases your likelihood of developing it, suggesting that genetics play some role.[3]
Classic Diagnostic Methods
The diagnosis of eosinophilic oesophagitis requires a combination of clinical history, symptoms, and specific test results. No single blood test or simple examination can confirm the condition. Instead, doctors rely on a procedure called an upper endoscopy with tissue sampling to make the diagnosis.[5]
Upper Endoscopy
An upper endoscopy, also called an esophagogastroduodenoscopy or EGD, is the essential procedure for diagnosing eosinophilic oesophagitis. During this examination, a doctor inserts a long, flexible tube equipped with a tiny camera and light through your mouth and down into your oesophagus. This tube, called an endoscope, allows the physician to see the inside of your oesophagus and look for signs of inflammation or damage.[8]
During the endoscopy, your doctor examines the oesophageal lining for specific visual features. In many patients with eosinophilic oesophagitis, the oesophagus shows distinctive patterns. These can include white spots or patches on the lining, horizontal rings that give the oesophagus a corrugated appearance (sometimes described as looking like rings on a tree trunk), vertical furrows or grooves running lengthwise, narrowing of the oesophagus called strictures, and areas that tear easily or appear fragile.[8]
However, it’s important to know that some people with eosinophilic oesophagitis have an oesophagus that looks completely normal during the examination. The absence of visible changes doesn’t rule out the condition. This is why taking tissue samples is absolutely necessary for diagnosis.[9]
Oesophageal Biopsy
The definitive way to diagnose eosinophilic oesophagitis is through biopsy, which means taking small pieces of tissue from the oesophageal lining during the endoscopy. These tissue samples are typically very small, about the size of a pen tip. The doctor takes multiple samples from different areas of the oesophagus to ensure accurate results.[5]
After the procedure, the tissue samples are sent to a laboratory where a specialist called a pathologist examines them under a microscope. The pathologist looks for an unusually high number of eosinophils, which are a type of white blood cell. In a healthy oesophagus, there should be no eosinophils present. In eosinophilic oesophagitis, the pathologist will find 15 or more eosinophils when viewing the tissue through the microscope at high magnification (per high-power field).[10]
Finding this elevated number of eosinophils in the oesophageal tissue, combined with symptoms of oesophageal dysfunction, confirms the diagnosis. The biopsy results are essential because eosinophils in the oesophagus can appear in other conditions too, such as acid reflux disease, certain infections, or other inflammatory disorders. Your doctor needs to rule out these other possibilities before confirming eosinophilic oesophagitis.[5]
Distinguishing from Other Conditions
Because several conditions can cause similar symptoms or show eosinophils in oesophageal tissue, your doctor must carefully distinguish eosinophilic oesophagitis from other diseases. One of the most common conditions that must be ruled out is gastroesophageal reflux disease (GERD), where stomach acid flows back into the oesophagus and causes irritation. GERD is much more common than eosinophilic oesophagitis and can sometimes also show eosinophils in the oesophagus, though usually in smaller numbers.[4]
Other conditions that doctors consider include infections of the oesophagus (from fungi, viruses, or bacteria), celiac disease (an immune reaction to gluten that can affect the digestive system), inflammatory bowel diseases like Crohn’s disease, and a rare condition called hypereosinophilic syndrome where eosinophils are elevated throughout the body, not just in the oesophagus.[4]
Additional Testing
Beyond the endoscopy and biopsy, your doctor may order additional tests to better understand your condition and identify possible triggers. Blood tests can measure your total number of eosinophils in the bloodstream and check levels of immunoglobulin E (IgE), a substance the immune system produces during allergic reactions. High levels of either can suggest that allergies are playing a role in your condition.[8]
Some doctors may recommend allergy testing to identify specific foods or environmental substances that might be triggering the inflammation in your oesophagus. This can be done through blood tests or skin tests. However, the relationship between allergy test results and eosinophilic oesophagitis is complex. Having positive allergy tests doesn’t necessarily mean those specific allergens are causing your oesophageal inflammation, and you might react to foods that don’t show up on allergy tests.[8]
A newer diagnostic approach called an oesophageal sponge test is being studied in some medical centers. This involves swallowing a capsule attached to a string. The capsule dissolves in your stomach, releasing a small sponge that is then pulled back up through the oesophagus by the string. As it travels upward, the sponge collects cells from the oesophageal lining, which can then be examined for eosinophils. This test can be performed in a doctor’s office without the need for sedation, potentially making monitoring easier and less invasive. However, it is not yet widely available.[8]
Diagnostics for Clinical Trial Qualification
When researchers conduct clinical trials to test new treatments for eosinophilic oesophagitis, they use specific diagnostic criteria to determine which patients can participate. These criteria are often more detailed and standardized than what might be used in regular clinical practice, ensuring that all study participants have similar characteristics and disease severity.[10]
The cornerstone of clinical trial enrollment is confirming the diagnosis through upper endoscopy with multiple biopsies showing the characteristic number of eosinophils. Most clinical trials require patients to have at least 15 eosinophils per high-power field in at least one biopsy sample from the oesophagus. Some studies may require evidence from multiple areas of the oesophagus or a certain average count across all samples taken.[10]
Patients must also have documented symptoms of oesophageal dysfunction. For adults and teenagers, this typically means difficulty swallowing solid foods, food impaction episodes, or chest pain when eating. For younger children, qualifying symptoms might include vomiting, poor appetite, failure to gain weight appropriately, or feeding difficulties. The severity and frequency of these symptoms are often measured using standardized questionnaires that patients or parents complete.[10]
Clinical trials usually require that other conditions causing oesophageal eosinophilia have been ruled out. This means participants must undergo testing to exclude infections, celiac disease, inflammatory bowel disease, and other disorders that could explain their symptoms and biopsy findings. Sometimes this involves additional blood tests, biopsies from other parts of the digestive system, or specific diagnostic procedures.[10]
Many trials examine how well patients respond to stopping certain medications before enrolling them. For example, some studies require that participants have continued to show eosinophilic inflammation despite taking proton pump inhibitors for a specified period, often eight weeks or longer. This helps ensure that the inflammation isn’t simply due to acid reflux that could be managed with standard treatments.[11]
Researchers often use endoscopy to assess not just the microscopic appearance of tissue but also the visible features of the oesophagus. They may document the presence and severity of rings, furrows, white patches, strictures, or other abnormalities using standardized scoring systems. These visual features help researchers categorize patients by disease severity and track whether treatments lead to healing of the oesophageal lining.[10]
Before and during clinical trials, participants typically undergo repeat endoscopies at specified intervals to monitor how their oesophageal inflammation responds to the treatment being studied. These procedures, performed at baseline (before treatment starts) and at predetermined times during and after treatment, allow researchers to measure objective changes in eosinophil counts and oesophageal appearance, not just rely on patients’ reports of symptom improvement.[10]
Some clinical trials also collect additional research samples during diagnostic procedures. This might include extra tissue biopsies for genetic analysis, measurements of immune system molecules in the oesophageal tissue, or samples to study the types of bacteria and other microorganisms living in the oesophagus. These research specimens help scientists better understand what causes eosinophilic oesophagitis and how treatments work.[12]
Quality of life assessments are another important component of clinical trial diagnostics. Researchers use validated questionnaires to measure how the disease affects patients’ daily activities, emotional well-being, and social functioning. These assessments help determine whether new treatments not only reduce inflammation and symptoms but also improve patients’ overall experience of living with the condition.[10]
