The only way to confirm a celiac disease diagnosis is by having an endoscopic biopsy. A pathologist will assign a Marsh classification to the biopsy findings.
Why an Endoscopic Biopsy?
An endoscopic biopsy will tell you (1) if you have celiac disease, (2) if your symptoms improve on a gluten-free diet due to a placebo effect (you feel better because you think you should) or (3) if you have a different gastrointestinal disorder or gluten sensitivity which responds to change in your diet. Read about other conditions that cause similar symptoms as celiac disease.
If the results of the antibody or genetic tests are positive, your doctor may suggest an endoscopic biopsy. An endoscopy is a procedure that allows your physician to see what is going on inside your GI tract. A scope is inserted through the mouth and down the esophagus, stomach and small intestine giving the physician a clear view and the option of taking a sample of the tissue.
This is usually an outpatient procedure. Samples of the lining of the small intestine will be studied under a microscope to look for damage and inflammation due to celiac disease. It is recommended that the doctor take at least 4 duodenal samples, including at least 1 from the duodenal bulb, in order to obtain an accurate diagnosis.
IMPORTANT: For biopsy results to be accurate, you must be eating gluten (at least 4 slices of bread) for one to three months prior to the procedure. Check with your physician to confirm this.
What To Expect During Your Endoscopy
This procedure takes a little less than thirty minutes and, for adults, sedatives and local anesthetics are used. Children are usually put under general anesthesia. During the biopsy, the gastroenterologist will insert a small tube with a camera through the digestive tract to the small intestine. Once there, the physician will examine the duodenum and take multiple tissue samples due to the “patchy” nature of villous atrophy. The tissue samples will then be examined by a pathologist under a microscope and assigned a Marsh classification.
Patients who cannot or will not tolerate an endoscopy may be given the option to undergo video capsule or “pill” endoscopy where a capsule the size of a large vitamin pill is swallowed that takes thousands of pictures of the small intestine. However, currently there is no conclusive evidence that this can substitute for traditional endoscopy and biopsy.
Marsh 0: The mucosa (intestinal lining) is normal, so celiac disease is unlikely. Stage 0 is known as the “pre-infiltrative stage.”
Marsh I: The cells on the surface of the intestinal lining (the epithelial cells) are being infiltrated by white blood cells known as lymphocytes. This is also seen in tropical sprue, giardiasis, acute infective enteropathy, H. pylori gastritis, Crohn’s disease, during NSAID usage, and in various autoimmune disorders so is not specific for celiac disease.
Marsh II: The changes of Marsh I are present (increased lymphocytes), and the crypts (tube-like depressions in the intestinal lining around the villi) are “hyperplastic” (larger than normal).
Marsh III: The changes of Marsh II are present (increased lymphocytes and hyperplastic crypts), and the villi are shrinking and flattening (atrophy). Most patients with celiac disease are Marsh III. There are three subsets of Marsh III: Partial villous atrophy, Subtotal villous atrophy, Total villous atrophy
Marsh IV: The villi are totally atrophied (completely flattened) and the crypts are now shrunken, too.
Is Endoscopy Really Necessary if My Blood Test is Positive or I feel better on a Gluten-Free Diet?
To confirm a celiac disease diagnosis the endoscopic biopsy is necessary. The blood tests indicate whether there is a possibility of celiac disease but you cannot confirm the diagnosis until an endoscopic biopsy is taken with one exception:
For individuals with dermatitis herpetiformis (DH), a skin biopsy is sufficient for diagnosis of both DH and celiac disease. This biopsy involves collecting a small piece of skin near the rash and testing it for the IgA antibody. It is not necessary to perform an endoscopicl biopsy to establish the diagnosis of celiac disease in a patient with DH; the skin biopsy is definitive.
A gluten-free diet is low in vitamins, minerals and fiber.