Appendix

Your appendix is a small, thin pouch of tissue attached to your large intestine. It’s in the lower right part of your abdomen. Scientists used to think it was a vestigial organ. That means it had no known function. Research now shows that your appendix is an important organ for your overall health. This is especially true in early life, when your immune system is developing.

What does the appendix do?

For a long time, scientists didn’t think your appendix had any purpose. But research now shows it plays a role in keeping your body healthy.

Appendix functions include:

• Immune system partnership: Your appendix has a lot of immune cells (especially B cells and T cells). These cells help your body fight germs and make antibodies. This helps your immune system learn which bacteria and viruses are safe and which can make you sick.
• Beneficial bacteria storage: Your appendix acts as a safe house for good bacteria in your gut. These bacteria return to your intestines after an illness and help keep digestion running smoothly.
• Microbiome balance: Your appendix helps maintain a healthy balance between good and harmful bacteria in your gut. By supporting helpful microbes and immune defenses, it can prevent bad bacteria from taking over.

What side is your appendix on?

Your appendix is located on the lower right side of your abdomen, where your small intestine meets your large intestine. It sticks out from your cecum. Your cecum is the first part of your large intestine near the end of your small intestine.

How big is the appendix?

Your appendix is a small, tube-shaped organ that hangs off your large intestine. It’s usually about 3 to 4 inches long — about the length of a middle finger.

What is the structure of the appendix?

Even though it’s small, your appendix has a complex structure. Its layers include:

• Mucosa: The innermost layer that lines the appendix
• Submucosa: A layer with lots of lymphoid tissue (immune system cells)
• Muscularis propria: A layer of muscle that helps move contents
• Serosa: The outer protective layer

What are the common conditions and disorders that affect the appendix?

The most common condition affecting your appendix is appendicitis. This occurs when an infection causes swelling and irritation. Appendicitis is a medical emergency. If left untreated, your appendix can burst (rupture). You need surgery immediately to remove your appendix (appendectomy).

Less commonly, conditions that affect the appendix can include:

• Appendix microbiome imbalance: Your appendix normally has a mix of bacteria that helps your gut. If something disrupts its balance, it may trigger inflammation or affect your immune system.
• Loss of lymphoid tissue: Over time, the lymphoid tissue in your appendix shrinks, and scar tissue replaces it. This can change the structure and immune function of your appendix.
• Appendicolith: An appendicolith is a hard, stonelike lump made up of small pieces of poop and minerals. They clump together in your appendix.
• Rare tumors or growths: Unusual conditions like appendix cancer can occur, but they’re less common.

Signs/symptoms something isn’t working right

If you have any of the following symptoms, it could have something to do with your appendix:

• Pain in your lower right belly
• Nausea and vomiting
• Fever
• Tenderness to the touch in your lower right belly
• Change in pooping habits
• Loss of appetite

These symptoms usually mean your appendix is inflamed or your microbiome/immune function is disrupted. It’s important to get medical attention right away.

Is there anything I can do to keep my appendix healthy?

Your appendix plays a role in immunity and gut bacteria. You can keep it healthy by supporting your gut and immune system:

• Drink water to keep your digestive system working smoothly.
• Eat more fiber to feed healthy bacteria in your gut.
• Try probiotic foods — like yogurt, kefir and sauerkraut — occasionally to support gut bacteria.
• Limit processed foods and excess sugar, which can disrupt your gut bacteria balance.
• Stay physically active to support healthy digestion and overall immune function.
• Avoid unnecessary antibiotics (when possible), which can kill helpful bacteria.
• Manage stress, which can upset your gut health.

Can you live without your appendix?

Your appendix has several important immune and microbiome roles. If you need to have it removed, you may have fewer good bacteria in your gut. You also have a small increase in your risk of developing certain infections or immune-related conditions over time.

But most people go on to live healthy lives without the appendix. This is because your body adjusts. The rest of your gut and immune system make up for the loss.