Rarely, Crohn’s disease can cause acute inflammation of the appendix. It can be difficult to diagnose partly because it’s so rare.

Crohn’s disease is a chronic inflammatory bowel disease that affects the gastrointestinal (GI) tract. It commonly affects the small intestine or large intestine. Symptoms can include abdominal pain and diarrhea.

Appendicitis is inflammation of the appendix, a small pouch attached to the large intestine. It’s considered a medical emergency that requires immediate treatment to prevent serious complications. The most common symptom is severe abdominal pain.

One possible cause of appendicitis is inflammatory bowel disease. Here’s what you need to know about the connection between Crohn’s disease and appendicitis.

Although rare, Crohn’s disease can cause acute inflammation of the appendix. This is called appendiceal Crohn’s disease (ACD). Studies estimate ACD occurs in only 0.2% to 0.5% of appendicitis cases.

According to a 2020 case report, ACD is often accompanied by:

  • inflammation of the ileum, or final section of the small intestine
  • inflammation of the colon, or large intestine
  • abdominal pain and diarrhea

Most often, ACD causes abdominal pain in the lower right area of the abdomen. About 25% of people who experience ACD report other symptoms of Crohn’s disease, such as chronic abdominal pain and bowel discomfort.

It’s uncommon for Crohn’s disease to affect only the appendix without any prior symptoms of bowel discomfort, especially in older adults. ACD occurs more commonly in younger people, according to research.

ACD can be difficult to diagnose and is often confused with acute appendicitis unrelated to Crohn’s disease. There are several reasons for this, including:

  • the rarity of ACD
  • pain in the lower right abdomen occurs with both ACD and non-Crohn’s-related appendicitis
  • the inaccessibility of the appendix for diagnostic testing

Typically, ACD is diagnosed after surgical removal of the appendix (appendectomy) to treat appendicitis. After surgery, doctors will examine the removed appendix to help determine what caused the inflammation. Certain signs may indicate Crohn’s disease, including:

  • wall thickening
  • lymphoid aggregates (collections of cells present in some organs)
  • lumps of tissue, called granulomas, that develop in response to chronic inflammation

Appendicitis involving granulomas is called granulomatous appendicitis. It’s a rare disease that can be caused by infections like Mycobacterium tuberculosis and noninfectious causes like Crohn’s disease.

Recent research suggests that newly identified genetic mutations, as well as laboratory findings like low hemoglobin levels and elevated platelet counts, may help doctors diagnose ACD earlier. An earlier diagnosis of ACD may help lower the risk of potential complications following an appendectomy.

Possible causes of appendicitis can include:

  • hardened stool or growths that block the opening of the appendix
  • enlarged tissue in the wall of the appendix caused by infection in the GI tract
  • inflammatory bowel disease

In many cases, the cause of appendicitis is unclear.

Doctors don’t fully understand what causes Crohn’s disease. Experts believe certain factors may play a role, including:

  • bacteria in the GI tract that trigger the immune system, causing inflammation
  • genetics
  • smoking
  • high fat diet

A 2023 systematic review found that an appendectomy may increase the risk of developing Crohn’s disease after the procedure. But more research is needed on this link.

Acute appendicitis with Crohn’s disease is uncommon.

A 2014 review of appendectomy specimens from more than 5 years at a hospital found that only 0.5% showed features of Crohn’s disease.

Other studies have estimated the prevalence of ACD to be 0.2% to 0.5%.

The most common early warning symptom of ACD is persistent and severe pain in the abdomen, especially in the lower right area. The pain may feel different than any pain you’ve ever felt.

Other symptoms of ACD can include:

  • swelling and cramping in the abdomen
  • bowel discomfort, such as diarrhea, constipation, or an inability to pass gas
  • fatigue
  • nausea or loss of appetite
  • weight loss
Medical emergency

Appendicitis is a medical emergency that requires immediate treatment to prevent serious complications, such as a burst appendix, abscess of the appendix, or serious infection. If you suspect you may be experiencing symptoms of appendicitis, go to the emergency room or call 911 or local emergency services right away.

A doctor can help treat appendicitis, manage symptoms, and lower the risk of complications.

If you aren’t sure you’re experiencing appendicitis but are concerned about symptoms linked to Crohn’s disease, speak with a doctor. They can evaluate your symptoms and provide a diagnosis to help determine the best approach to treatment.

Crohn’s disease can cause acute appendicitis, but it’s uncommon.

Appendicitis can have many different causes, and the cause is often not known. Appendicitis caused by Crohn’s disease can be difficult to diagnose, in part because it’s so rare.

The most common treatment for appendicitis is surgery to remove the appendix. In most cases, this procedure can cure ACD. Researchers are continuing to study the best diagnostic and treatment approaches for ACD to improve outcomes.

Speak with a doctor or go to an emergency room if you suspect you may be experiencing appendicitis.