Endoscopy and intestinal biopsy

Endoscopy and intestinal biopsy are key procedures for the diagnosis of celiac disease. In this section, we will explain in detail what both techniques consist of, how they are performed, what their indications are and how the results are interpreted.

If the serology test result is positive and the patient is an adult, these procedures should be performed to confirm the diagnosis.

If the serology is negative, but there is still suspicion of celiac disease either by symptoms or family history of the person, it is also advisable to perform an endoscopy and intestinal biopsy.

Preparation for the procedures

Endoscopy and intestinal biopsy are safe and well-tolerated procedures with few complications. However, they are still invasive procedures and may cause mild discomfort, such as sore throat and abdominal discomfort.

General preparation guidelines include

• Fasting: Fasting is usually required prior to the procedure to ensure that the stomach and bowel are empty during the endoscopy. This may involve not eating or drinking anything for several hours prior to the procedure, as directed by your physician.

• Stopping medications: Some medications may interfere with the endoscopy and bowel biopsy, so you may be instructed to discontinue certain medications prior to the procedure. Be sure to inform your physician of any medications you are taking.

• Report allergies and medical conditions: It is important to inform your physician if you have any known allergies, especially allergies to medications or materials used in the endoscopy procedure, as well as any medical conditions that may require special attention during the procedure.

• Follow dietary restrictions: Depending on your physician's instructions, you may be asked to follow specific dietary restrictions prior to the procedure, such as avoiding red or black foods and beverages that may interfere with the visualization of tissues during endoscopy.

In addition to these recommendations, the specialist may give other indications to follow. It is important to note that these tests should be performed on people who still consume gluten in order to obtain accurate results and avoid false negatives.

Description of the procedures

Endoscopy is a procedure performed using an endoscope, a thin, flexible tube with a small camera and a light on the end. Endoscopy is used to visualize the inside of the gastrointestinal tract, from the esophagus to the small intestine.

During the procedure, the patient is placed in a lateral position and a local anesthetic is administered in the throat to avoid discomfort. The endoscope is then inserted through the mouth and directed into the duodenum, the first part of the small intestine.

During endoscopy, the endoscope looks for evidence of damage to the small intestine, which can be caused by inflammation from exposure to gluten in people with celiac disease.

The damage can be visualized through the endoscope as a bowel with flatter than normal folds, and a paler and thinner mucosa than would be expected in a healthy person.

If areas suspicious for celiac disease are identified, biopsies, which are small tissue samples for microscopic analysis in the laboratory, can be taken. Biopsies are obtained using special instruments inserted through the endoscope.

Tissue samples are taken from different parts of the upper small intestine, including the duodenum and proximal jejunum. Taking multiple samples from different areas of the small intestine helps to increase the accuracy of the diagnosis, as celiac disease can have an irregular distribution and lesions can be difficult to detect with the naked eye during endoscopy.

The number of samples may vary depending on the protocol and practice of the physician performing the procedure, as well as the appearance of the bowel lining during endoscopy. In general, at least four samples are taken from different parts of the small bowel.

The samples are sent to the laboratory for analysis by a pathologist, where they are evaluated for the presence of lesions typical of celiac disease, such as lymphocyte infiltration of the intestinal mucosa and atrophy of the intestinal villi.

The exact time it takes for an endoscopy with intestinal biopsy may vary according to several factors, such as the technique used, the physician's experience, the need for additional biopsies and the specific condition of the patient. However, in general, an endoscopy with intestinal biopsy usually lasts between 15 and 30 minutes.

The time it takes to receive the results of intestinal biopsies performed during an endoscopy may vary depending on the laboratory and the medical center where the analysis is performed. It can take several days, as it involves preparation of the specimens, histological sections, staining of the specimens and microscopic review by a pathologist. On average, they are usually available in approximately 3 to 7 working days after the procedure is performed.

Intestinal biopsy result

Interpretation of the intestinal biopsy result is based on the Marsh classification, which assesses the severity of damage to the intestinal lining on a scale of 0 to 3. The degree of damage can be an indicator of the severity of the disease and can help establish an appropriate treatment plan.

In general, grades 3a, 3b and 3c are considered indicative of celiac disease, with grade 3c being the most severe. However, it is important to note that negative intestinal biopsy results do not rule out celiac disease, as there may be cases of latent celiac disease or mild lesions that are not detected on biopsy.

The Marsh scale ranges from less severe to more severe:

• Grade 0: There are no significant histologic changes in the intestinal villi.

• Grade 1: There is inflammatory cell infiltrate in the lamina propria of the small bowel lining, but the villi are intact.

• Grade 2: In addition to inflammation, there is evidence of partial atrophy of the intestinal villi, with preservation of some villi.

• Grade 3a: There is subtotal or complete atrophy of the intestinal villi, with presence of short or absent villi.

• Grade 3b: Similar to grade 3a, but with the additional presence of crypt hyperplasia (increase in size and number of intestinal crypts).

• Grade 3c: In addition to 3a and 3b, there is also infiltration of inflammatory cells on the surface of the small bowel lining.

Interpretation of the histologic findings of intestinal biopsy in the full clinical context is critical, and should be performed by a pathologist experienced in the diagnosis of gastrointestinal diseases, in coordination with the patient's clinical evaluation and other test results.

If after evaluating the results of different tests the diagnosis is positive, it means that the person is celiac regardless of the degree of damage in the small intestine. Even if the damage is mild, the same treatment, a gluten-free diet, should be started.