Celiac disease is an autoimmune disorder where consuming gluten, a protein found in wheat, barley, and rye, causes an immune reaction in the small intestine. This reaction damages the lining of the small intestine, preventing the proper absorption of nutrients. An upper endoscopy is a central component in the diagnostic process for celiac disease, serving as the definitive method to confirm the condition after initial screening. The procedure allows doctors to physically examine the intestinal lining and collect tissue samples for microscopic analysis.
Screening for Celiac Disease
The diagnostic journey for celiac disease begins with blood tests, known as serology, rather than an immediate endoscopy. These tests are designed to detect specific antibodies the immune system produces in response to gluten exposure. The primary test measures the tissue transglutaminase immunoglobulin A (tTG-IgA) antibody, which is highly sensitive and specific for celiac disease.
A total serum IgA test checks for an IgA deficiency, a condition sometimes associated with celiac disease that could lead to a false-negative tTG-IgA result. If serology results are positive, showing elevated levels of these celiac-specific antibodies, the patient is referred for an upper endoscopy. This blood work acts as a screening tool, indicating a strong likelihood of the condition.
The Upper Endoscopy Procedure
An upper endoscopy, also called an esophagogastroduodenoscopy (EGD), is performed by a gastroenterologist to examine the upper digestive tract. A thin, flexible tube equipped with a light and camera, called an endoscope, is guided through the mouth, esophagus, stomach, and into the duodenum. The procedure allows the physician to visually inspect the intestinal lining for signs of damage, such as scalloping of the folds or a nodular appearance.
Visualization alone is not sufficient to diagnose celiac disease. The definitive diagnostic step involves using tiny instruments passed through the endoscope to take multiple tissue samples, or biopsies, from the lining of the duodenum. For accurate results, the patient must remain on a gluten-containing diet leading up to the procedure. This is because the intestinal lining may otherwise begin to heal, leading to a misleadingly normal result, and damage can sometimes be patchy.
Analyzing Biopsy Findings
The tissue samples collected during the endoscopy are sent to a pathologist for microscopic examination. The pathologist looks for classic signs of gluten-induced damage, which include two main features: villous atrophy and crypt hyperplasia. Villous atrophy refers to the flattening or shortening of the villi, the tiny, finger-like projections responsible for absorbing nutrients.
Crypt hyperplasia is the counter-reaction, where the crypts (glands at the base of the villi) become elongated in an attempt to compensate for the damaged surface area. Pathologists use the Marsh classification system to grade the severity of this damage. This system categorizes the injury from Marsh Type 1 (increased immune cells but normal structure) up to Marsh Type 3c (complete villous atrophy). A Marsh Type 3 lesion, which indicates the presence of villous atrophy, confirms the diagnosis of celiac disease alongside positive serology.
Confirming the Diagnosis and Next Steps
The diagnosis of celiac disease is achieved when the patient has positive celiac serology and the intestinal biopsy confirms damage to the small intestine. This two-part confirmation ensures the diagnosis is accurate and not due to other conditions that can mimic celiac disease symptoms. With the diagnosis confirmed, the immediate next step is the implementation of a strict, lifelong gluten-free diet (GFD).
The GFD is the only treatment for celiac disease, as it removes the trigger for the immune reaction, allowing the small intestine to heal over time. Patients are referred to a dietitian specializing in celiac disease to help them navigate this significant dietary change, including learning about hidden sources of gluten. Follow-up care monitors symptoms, checks for the healing of the intestinal lining, and assesses for any resulting nutritional deficiencies.