The appendix is a small organ situated between the small and large intestines. For a long time, scientists didn’t know its function and deemed it useless. In fact, it was seen as potentially dangerous. The appendix is famous mostly because of appendicitis, which can be deadly if it causes a rupture. In these cases, doctors must remove the organ in a procedure known as an appendectomy, which has saved countless lives for centuries. However, new research is realizing appendices may serve an important function after all.
What is the purpose of the appendix?
Heather Smith was 12 years old and anticipating a family ski trip when she got appendicitis and an emergency appendectomy. She still has the scar and a lifelong curiosity about the organ, its purpose, and why it gets inflamed. Today, she is a professor of anatomy at Midwestern University, editor-in-chief of the journal The Anatomical Record, and has thoroughly studied this organ once considered useless. “But it turns out recent research shows it does have functions that can help us,” Smith said to NPR.
Although Charles Darwin popularized the “useless appendix” theory, discussions about the purpose of this organ began long before him. Since people could live without it, it was reasonable at the time to believe it did nothing, Smith explained. “But now with modern technology, we can see things like the microanatomy and the biofilms in the appendix, and we have a better understanding of what it is and what it’s doing.”
According to phylogeny, the appendix has evolved multiple times, which indicates it adapts to serve a greater function for the mammal body. Today, researchers have determined it can play two important roles. One is supporting immune responses in the gut since the appendix contains a high concentration of immune tissue. A team from Duke University proposed the second purpose in 2007. In their scientific review, they claimed the appendix stored beneficial digestive bacteria. In times of infectious diarrhea where all the good bacteria get “flushed” out, the appendix is a “safe house” of bacteria that can recolonize the system. “So the appendix is kind of helping us in two ways, both within the gut. It’s helping to fight off invading pathogens, but also to repopulate the gut with this beneficial bacteria after gastrointestinal issues,” said Smith.
What causes appendicitis?
One common cause of appendicitis is an obstruction from a calcified fecal deposit, tumor, or foreign object, according to a 2022 review. This leads to a build-up of blood and lymph that can cause necrosis and a rupture that leaks the infection to other parts of the body. Once this occurs, there’s a high risk of sepsis and death, which is why appendicitis is considered a medical emergency. Appendicitis can also be a result of blunt force trauma. Tumors in the appendix are fortunately rare.
Medical experts used to subscribe to the hygiene hypothesis. This theory states that modern people over-sanitize with antibiotic and antibacterial products, leading to underdeveloped immune systems that don’t get exposed to pathogens older generations might have. So the immune system is prone to overreact, particularly in areas full of immune tissue, such as the appendix, causing appendicitis. However, this theory has since been largely rejected.
Infections, ulcerative colitis, and longevity
Recent studies have shown a link between appendectomies and a lower risk of ulcerative colitis. This condition is characterized by severe inflammation and ulcers in the rectum and colon. Research shows that people who had appendectomies before age 20 had a lower risk of developing ulcerative colitis, and those who did develop ulcerative colitis were less likely to need colon removal surgery to treat it. Since ulcerative colitis is an autoimmune disease, this lends credence to the theory that the appendix is part of the immune system.
However, the lowered risk may not be because of the surgery, but because of how the immune system reacted to the appendicitis itself. Researchers conducted follow-up studies where patients with ulcerative colitis unresponsive to treatment had their appendices removed, but the results were mixed, according to a 2023 review. Therefore, experts discourage appendectomies as a preventative treatment for ulcerative colitis, especially with the newfound potential benefits of the appendix.
For example, they aid the immune system. “Studies have shown that infections with the really bad, nasty bacteria C. diff tend to be higher in people who have had their appendix removed,” explained Smith. Plus, researchers have linked appendices with longevity when comparing mammals with this organ.
This is not necessarily bad news for those who had an appendectomy to treat appendicitis. “...Appendicitis at a young age is clearly beneficial by strengthening the education of the immune system and enabling it to fight any subsequent infection more effectively…” clarified Inserm researcher Eric Ogier-Denis from the French Museum of Natural History in a press release. “Only an appendectomy performed in a patient without appendicitis might have harmful consequences in the context of inflammatory and infectious bowel disease.”
Appendectomy alternatives
Keep in mind, surgery always comes with risks. No matter how necessary, appendectomies can lead to infections, bleeding, abscesses, bowel obstruction, and hernias. With this new understanding of appendices, scientists are looking into treatments for appendicitis that do not involve removal. In cases where the appendix is not at risk of rupture, doctors may prescribe antibiotics, beginning with intravenous antibiotics, then following up with oral antibiotics, according to UCLA Health. However, patients who don’t get appendectomies may develop new symptoms and are at risk of recurrence.
Symptoms of appendicitis
- Pain in the center of the abdomen that migrates to the lower right area of the abdomen
- Loss of appetite
- Nausea
- General unwellness
- Swollen abdomen
- Feeling the urge to urinate more frequently
- Constipation or diarrhea
- Fever
- Rebound tenderness (pain that occurs after applied pressure is suddenly released)
- Pain that worsens with coughing, walking, or raising the right leg
Remember, appendicitis is a medical emergency. If you suspect you have it, seek help immediately, especially if the pain worsens, according to Cleveland Clinic.
Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.
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