If you have been diagnosed with celiac disease or if you are going through the diagnostic process now, you know that the doctor has to get a sample of tissue from your small intestine to know for sure that you have celiac disease. This test is done by passing a tube down past your esophagus (food pipe) and stomach into your small intestine. The first part of the small intestine is called the duodenum, and samples must be taken from the lining there. Multiple tiny pieces need to be removed and analyzed, usually four to six.
It has long been believed that these samples need to be taken from the duodenum, but not immediately after it exits from the stomach. The first part of the duodenum is called the duodenal bulb, and it does not look exactly the same under a microscope as the rest of the small intestine. It has been believed that the differences between the bulb and the rest of the duodenum would make it hard to diagnose celiac disease based on biopsies of the bulb.
During the last few years, research has been published indicating that some people only have evidence of celiac disease in the duodenal bulb. These patients would have their diagnosis missed if the duodenal bulb was not biopsied.
This was first seen in children. A study was done in which children (average age around 8 years) with positive blood tests for celiac disease had biopsies, with two samples taken from the duodenal bulb and four from the rest of the duodenum. All the biopsy specimens were examined. Out of 35 patients, 4 had samples that showed the appearance of celiac disease only in the duodenal bulb. If standard procedures had been done, these four patients would hot have been diagnosed with celiac disease.
In another study of children with the average age of 8 years, the doctors doing the biopsies took 4 samples from the duodenal bulb and 4 from the rest of the duodenum. In this group, 5 out of 47 children only had changes in the biopsies from the duodenal bulb, leading to the same conclusion. These cases of celiac disease would have been missed with the standard procedure.
This study also looked at how much damage was visible in the biopsies. In 11 of the 47 children, the disease was visibly worse in the duodenal bulb than the duodenum. Finally, all of the bulb specimens confirmed celiac disease, so that taking samples only in the bulb would not have missed any cases of CD.
The researchers who did this study emphasized how important it is not to miss the diagnosis of celiac disease in children. With the correct diagnosis, staying on a gluten-free diet can make very sick children essentially healthy and prevent or correct many problems.
Others have looked at this same issue in adults. One group of researchers decided to compare traditional biopsy sites from the duodenum with bulb biopsies in adults (ages 16 to 89 years) who were having their first biopsy for diagnosis, There were reasons to suspect celiac disease in these cases, either from blood tests, history or other illnesses associated with CD. Adults having follow-up biopsies were also included in this study.
The researchers took 1 biopsy from the duodenal bulb and 4 from the rest of the duodenum. There were 461 patients in the study. 85 already had the diagnosis of celiac disease established. 126 new cases were found as the result of the biopsies.
A total of 23 patients, 11 diagnosed during this study and 12 who were already diagnosed had biopsies that showed celiac disease in the duodenal bulb only. Four patients, 2 with established disease and 2 newly diagnosed had positive biopsies in the duodenum only. Also, 24 out of 31 patients with known CD and 16 newly diagnosed had more severe damage visible in the duodenal bulb.
What all of this means is that the diagnostic process for celiac disease continues to be studied and continues to change. Your doctor may or may not include the duodenal bulb during biopsy now. It seems likely that more doctors will biopsy the duodenal bulb as time goes on, and that this may prevent them from missing cases of celiac disease.
Rashid, M., MacDonald, A. Importance of duodenal bulb biopsies in children for diagnosis of celiac disease in clinical practice. BMC Gastroenterology 2009; 9 :78.
Mangiavillano, B., Masci, E., Parma, B., et al. Bulb biopsies for the diagnosis of celiac disease in pediatric patients. Gastrointestinal Endoscopy 2010; 72: 564-8.
Evans, K.E., Aziz, I., Cross , S.S., et al. A Prospective Study of Duodenal Bulb Biopsy in Newly Diagnosed and Established Adult Celiac Disease. American Journal of Gastroenterology. Advance online publication, 24 May 2011.
Photo: Biopsy of small bowel showing coeliac disease manifested by blunting of villi, crypt hyperplasia, and lymphocyte infiltration of crypts – courtesy Samir @ Wikipedia