Help us help you! A Practical Approach to Biopsying the GI Tract (Part 2)
Part 2 — Lower GI tract
Optimal biopsy sampling will help your expert Inform Diagnostics GI pathologist to render a specific and accurate diagnosis. In the gastrointestinal tract, it is often important to sample normal-appearing as well as abnormal-appearing mucosa, as many disorders are histologically patchy. In addition, the endoscopic appearance may not correlate with histologic findings (marked Helicobacter gastritis may appear endoscopically normal). Continuing from our last issue of Focus, the outline below summarizes the biopsies that we recommend taking to allow us to provide you with the most clinically useful diagnostic information.
Diarrhea: While the diagnostic yield is generally low in ileal biopsies that appear endoscopically normal, some patients with celiac disease may exhibit increased intraepithelial lymphocytes at this site. Suspected idiopathic inflammatory bowel disease (IBD): All cases of suspected IBD should include a terminal ileal biopsy, if possible. This can be very important in determining whether a case of IBD represents ulcerative colitis or Crohn’s disease, even when the endoscopic features are strongly suggestive of one or the other.
Evaluation for microscopic colitis: Multiple biopsies from the right (including transverse) and left colon. These biopsies should be submitted in separate jars (right and left), as the normal complement of intraepithelial lymphocytes is greater in the proximal colon, and comparison of the left and right colon can be helpful in the histologic evaluation for microscopic colitis.
Suspected IBD (new diagnosis): Sampling of the terminal ileum as well as each anatomic region of the colon (ascending, transverse, descending, and rectum) is recommended. Separately labeled and submitted jars from each biopsy site are very important in cases of suspected IBD. This is because knowledge of both the gross and microscopic distribution of disease is essential in classifying IBD, and endoscopically normal-appearing areas may show patchy microscopic features of Crohn’s disease.
IBD dysplasia surveillance: Eight biopsies from each region (ascending, transverse, descending, and rectum), submitted in separately labeled jars.
Polyp or lesion in IBD: Biopsy or excision of the polyp or lesion submitted in its own jar(s); base of polyp or lesion (also in a separate jar); in addition, background surveillance biopsies should be collected and submitted as above.
Lash JG, Genta RM. Adherence to the Sydney System guidelines increases the detection of Helicobacter gastritis and intestinal metaplasia in 400,738 sets of gastric biopsies. Aliment Pharmacol Therapy 2013;38:424-431.
Lash RH, Taylor SL, and Genta RM. Optimal tissue sampling: the pathologist’s perspective. In: Weinstein WM, Hawkey CH, and Bosch J, eds. Textbook of Clinical Gastroenterology and Hepatology Mosby:Chapter 144;2012.