Inflammatory Bowel Disease (IBD)

What is Inflammatory Bowel Disease (IBD)? Inflammatory bowel disease (IBD) is a classification comprising two gastrointestinal diseases, ulcerative colitis (UC) and Crohn’s disease (CD), that cause severe discomfort stemming from an inappropriate inflammatory process. A small percentage of cases diagnosed as IBD exhibit features of both diseases and cannot be diagnosed definitively. These cases are termed indeterminate colitis.

What are the similarities between the two types of IBD?

UC and CD are similar in significant ways, which makes it important to obtain a careful history to make an accurate diagnosis.

The onset of both diseases can occur at any age, but often develops in teenage and young adult years, affecting all genders equally. 

The pathomechanism of disease of IBD has not been completely elucidated, but both diseases are thought to develop through multifactorial influences, including genetics, inappropriate immune activation, and environmental risk factors. 

Some symptoms, such as abdominal cramping and bloody stools, may be present in either disease. During visualization through endoscopy, the affected mucosa also has similar features, and may include a loss of vascularity, erythema, mucosal granularity, friability, erosions, and pseudopolyps.

What are the differences?

Despite the similarities, the two inflammatory bowel diseases differ in basic ways.

  • Location: Ulcerative colitis is limited to the colon, while Crohn’s disease may occur at any place in the GI tract, although the rectum is often spared in Crohn’s disease. Crohn’s disease can also involve the vagina.
  • Depth of involvement: UC affects the mucosal wall, while CD causes transmural damage.
  • Symptoms: Bloody diarrhea and urgency are more common in UC, while CD is more frequently characterized by malabsorption and weight loss. There is also a greater risk of colon cancer in those with UC overall, although the risk of cancer is also elevated in CD, but only in those with colonic involvement. The onset of UC is also often more insidious.
  • Gross features: Abscesses, fistulas, strictures, cobblestoning, and skip lesions are more common in CD, while a continuous pattern is more common in UC.

Source: Flynn, S., & Eisenstein, S. (2019). Inflammatory Bowel Disease Presentation and Diagnosis. Surgical Clinics of North America, 99(6), 1051–1062.