Difference 2: Depth of Inflammation – A Matter of Depth
The depth of inflammation, or how deep the disease penetrates the bowel wall, is the second key difference between UC and CD. UC is a superficial disease, only affecting the innermost lining of the colon, known as the mucosa. It’s akin to a surface wound, rarely extending to the deeper layers of the bowel wall.
Contrastingly, CD is a transmural disease, meaning it affects the entire thickness of the bowel wall, from the innermost mucosa to the outermost serosa. This is similar to a deep wound that extends through all the layers of the skin. The transmural nature of CD distinguishes it significantly from UC and accounts for many of its unique symptoms and complications.
The impact of this difference in the depth of inflammation is vast. Firstly, it influences the appearance of the bowel during diagnostic procedures. UC, being a mucosal disease, leads to superficial ulcerations that are visible during endoscopic procedures, while CD can lead to deeper, more extensive lesions that may be evident on imaging studies like CT or MRI.
Secondly, this difference also affects the disease’s clinical manifestations. The transmural inflammation in CD can lead to complications like fistulas, which are abnormal connections between the bowel and other organs or the skin. These are rarely seen in UC due to its superficial nature.
Thirdly, the treatment strategies for the two conditions can vary based on the depth of inflammation. For example, certain medications that work well for superficial inflammation, like topical mesalamine, may not be as effective for CD due to its transmural nature.(2)
