What is an endoscopy?
An endoscopy is the minor surgical procedure when a small flexible tube is slid into the bowel. The tube has a light-source and camera at the tip. Tissue samples can be easily and painlessly taken by tiny forceps. I am often asked: Who needs an endoscopy?
- Gastroscopy is upper endoscopy (looking into the esophagus, stomach and duodenum the upper small bowel).
- Colonoscopy is lower endoscopy (looking into the rectum and colon).
Small bowel biopsy:
You have an upper gastroscopy in order to get the bowel tissue samples this is called a small bowel biopsy.
How does it help?
Bowel tissue samples: Endoscopy is an investigation to have a look at the upper bowel and to take tissue samples. It gives the opportunity to look for inflammation in the esophagus and stomach. This is useful in if you have ongoing gastro-esophageal reflux problems (GERD/GORD). The infection by Helicobacter pyloris can also be looked for in the gastric biopsy.
Sugar enzyme tests: Information about the function of the small bowel can also be obtained by small bowel biopsy. The disaccharidase tests measure the enzymes that digest sugars in the small intestine. This is the activity of the lactase, sucrase, and maltase enzymes. This test needs a living piece of bowel mucosa to accurately measure the activity of these enzymes.
These sugar enzymes are produced at the tip of the villi. When there is only subtle disturbance to the bowel, the damage might not show up as abnormal histology. But the damage may be enough to cause reduction in lactase and other enzyme activity.
The specific enzymes and their related sugars are:
- The enzyme Lactase (which digests the sugar Lactose);
- The enzyme Sucrase (which digests the sugar Sucrose);
- The enzyme Isomaltase (which digests the sugar Maltose).
Sugar enzyme function is always affected when there is significant histological damage.
Low levels of these enzymes is the cause of some of the diarrhoea and bloating. The poor sugar absorption is the reason why milk (which contains lactose) is often not tolerated. Usually, on a gluten-free diet, these sugars can again be eaten without any problems.
Who needs an endoscopy?
There are a number of indications for upper endoscopy:
Confirmation if coeliac disease: In my opinion, it is still important to confirm bowel damage from gluten. It is an extremely important investigation which should not be rejected lightly. The guidelines that I use to decide on who should have a biopsy are as follows:
- Those with elevated tissue damage antibodies (elevated tTG, positive EMA, or high DGP antibodies).
- In children who have substantially elevated IgA-gliadin levels (usually IgG-gliadin is also up).
- In children who are failing to thrive (poor growth) and who have negative gluten and tissue antibody markers.
Please stay on gluten foods until you have had your blood tests and endoscopy.
Investigation of gastric reflux: With on-going reflux it is valuable to see the amount of inflammation in the esophagus. Looking for eosinophilic esophagitis (EE) is important. Knowing the status of the esophagus helps with treatment decisions.
Diagnosis of Helicobacter pylori: This is an infection in the stomach that can be tested for by blood tests and breath tests. However, the biopsy sample of the stomach is the most accurate way to make the diagnosis. It is treated with antibiotics.
In summary, performing a small bowel biopsy is mostly about getting a sample of tissue from the upper small bowel to see what state the gut mucosa is in. However, a lot more information about the health of the upper gut can be derived from an endoscopy. It is a vital test. It is important that each person is assessed as an individual and that the decision about their biopsy criteria is fully discussed.
How accurate is the biopsy result for celiac disease
Unfortunately, the biopsy is not a completely accurate test. It cannot be regarded as the absolute gold standard. In non-speciality pathology departments, studies suggest that up to 20% of the reports are falsely negative. That means that the minor abnormalities in the tissue have been overlooked and thus reported as normal.
Also, it is very important to take the biopsy tissue from the correct location: that is in the duodenal bulb. Tissue taken lower down (from the distal duodenum or proximal jejunum) may be normal. Tissue damage might not extend very far down early in the disease process.
Finally, in early coeliac disease, the damage may be functional only: that means that the tissue histology early on will be normal (see links to: How early can you diagnose coeliac disease and Biopsy: is there a gold standard ).
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