What is the test of choice to confirm microscopic colitis?

What is the test of choice to confirm microscopic colitis?

• A. Colonoscopy
• B. CT colonography
• C. Colonic biopsy
• D. Stool calprotectin

Answer: (C)

Microscopic colitis is diagnosed by looking at the tissue under the microscope, not by how the colon looks on imaging or endoscopy. The mucosa often appears normal during colonoscopy, so confirming the diagnosis requires tissue sampling. Taking colonic biopsies during colonoscopy and sending them for histology is the test of choice. The histology will show either a thickened subepithelial collagen band (collagenous colitis) or increased intraepithelial lymphocytes (lymphocytic colitis), which establishes the diagnosis. Imaging-based tests like CT colonography or colonoscopy without biopsies don’t provide histologic confirmation, and stool calprotectin reflects general intestinal inflammation but isn’t specific or definitive for microscopic colitis.

Microscopic colitis is diagnosed by looking at the tissue under the microscope, not by how the colon looks on imaging or endoscopy. The mucosa often appears normal during colonoscopy, so confirming the diagnosis requires tissue sampling. Taking colonic biopsies during colonoscopy and sending them for histology is the test of choice. The histology will show either a thickened subepithelial collagen band (collagenous colitis) or increased intraepithelial lymphocytes (lymphocytic colitis), which establishes the diagnosis.

Imaging-based tests like CT colonography or colonoscopy without biopsies don’t provide histologic confirmation, and stool calprotectin reflects general intestinal inflammation but isn’t specific or definitive for microscopic colitis.