What Is the Main Cause of Appendicitis?

The cause of appendicitis is not always clear, but it's usually related to viral or bacterial infections, large intestine blockages, inflammatory bowel disease, abdominal trauma, and benign or malignant tumors.

The appendix is a small organ located in the lower right of your abdomen. It is joined to your large intestine. While researchers used to think the appendix had no function, some studies have shown that it may help immune systems function by acting as a storage space for beneficial gut bacteria.

Though its function is still being studied, we usually only think of our appendix when something goes wrong with it, resulting in appendicitis. Appendicitis is an inflammation of the appendix, and it is usually caused by an infection or blockage.

Appendicitis can occur at any age but is most common in people aged 10 to 30. Without treatment, the appendix may rupture, which can lead to a serious infection known as peritonitis (inflammation of a membrane that lines your inner abdominal wall and covers organs).

Appendicitis is a medical emergency and requires immediate treatment, usually an appendectomy (surgery to remove the appendix).

Symptoms of appendicitis may include the following:

• Sudden pain on the right side of your abdomen
• Abdominal pain that becomes significantly worse
• Abdominal pain that is worse with movement, such as coughing or walking
• Pain that wakes you from sleep
• Nausea and vomiting
• Loss of appetite
• Diarrhea or constipation
• Fever that may get worse
• Excess gas or an inability to pass gas

The cause of appendicitis is not always clear, but it’s usually related to one of the following:

Infection

Infection is one of the most common causes of appendicitis. A viral or bacterial infection causes the appendix to swell and fill with pus. The inflammation blocks blood flow to the appendix, which then starts to die.

At this point, the appendix can develop holes or tears or may even burst if it is not treated. If that happens, stool, pus, and mucus can leak into the abdominal cavity, resulting in a life-threatening infection.

Blockage

Sometimes appendicitis can be caused by fecal blockage of the large intestine. Normally, the appendix is open to the large intestine. When stool or bacteria from an infection enters the appendix, the tube joining the appendix to the large intestine becomes blocked. This blockage leads to inflammation and swelling.

Tumors

Rarely, appendicitis can be caused by tumors, both benign (noncancerous) and malignant (cancerous). These tumors are usually discovered when the appendix is removed because of appendicitis or during diagnostic tests for other issues.

Inflammatory bowel disease

Inflammatory bowel disease is a term that refers to inflammatory diseases of the intestines, such as Crohn’s disease and ulcerative colitis. This chronic inflammation can lead to inflammation of the appendix as well.

Abdominal trauma

Though it’s fairly infrequent, abdominal trauma can lead to appendicitis. This happens when there is a serious injury to the abdomen that causes a blockage of the appendix.

Appendicitis is a medical emergency that should be treated immediately. If you have any symptoms of appendicitis, call your doctor or go to the emergency room. Appendicitis can progress quickly, so you shouldn’t wait to seek treatment.

Your doctor will likely perform some or all of the following to diagnose appendicitis:

Physical exam

After hearing your symptoms, your doctor will conduct a physical exam to check for signs of appendicitis. If your doctor gently presses on your stomach and your pain becomes worse when the pressure is lifted, that can be a sign of inflammation in the peritoneum (the lining of the abdomen). Additionally, your doctor may check for signs that your abdomen is rigid or you are stiffening the muscles of your abdomen in response to pressure.

Another sign of appendicitis that your doctor can discover during a physical exam is called the Rovsing sign, which is present when pressure on the left side of your abdomen increases pain on the right side. If you are a woman, your doctor may also perform a pelvic exam to rule out other causes of abdominal pain.

Blood tests

Your doctor may do a blood test called a complete blood count (CBC) to check for a high white blood cell count, which indicates infection.

Urinalysis

Since abdominal pain can be a symptom of other issues, such as a kidney stone or a urinary tract infection (UTI), your doctor may test a sample of your urine to rule out problems other than appendicitis.

Imaging studies

Once other causes have been ruled out, your doctor may order an imaging study to confirm appendicitis. A test such as an X-ray, ultrasound, magnetic resonance imaging (MRI), or a computerized tomography (CT) scan will let your doctor see what is going on inside your body and determine if it is appendicitis or another medical issue.

Appendicitis is usually treated by removing the appendix and prescribing antibiotics. If the appendicitis case is mild and uncomplicated, it may be treated with only antibiotics, but this is not common.

Surgery for appendicitis is performed through one of the following methods:

Laparoscopy

Using this method, several small incisions are made in the abdomen to remove your appendix. This type of surgery has few complications and is not as risky as more invasive types of surgery.

Laparotomy

In this type of surgery, which is also called an open appendectomy, a single incision is made to the lower right abdomen to remove the appendix. This may be the best option if your appendix has ruptured or if you have an abscess that needs to be drained before surgery.

In either case, you may have to spend one or two days in the hospital after surgery before you’re sent home to recover.

During the postoperative period, you should get plenty of rest, avoid strenuous activity, and report any concerning symptoms to your doctor.