Inflammation of the Appendix

Table of Contents
View All
Table of Contents

Appendicitis is inflammation of the appendix, a small, finger-shaped organ that connects to the large intestine (also called the colon) in the lower right side of the abdomen.

When inflamed, the appendix swells and becomes filled with a thick, infectious fluid called pus. An inflamed appendix can rupture or burst open if not treated, allowing the pus to spill into and infect the abdominal cavity.

This article will provide insight into what causes the appendix to become inflamed. It will also highlight the symptoms, diagnosis, and treatment of appendicitis.

A large intestine with an inflamed appendix

Illustration by Mira Norian for Verywell Health

Can I Tell I Have Appendicitis at Home?

No, there is no way to diagnose appendicitis at home. You can, however, be on the lookout for symptoms, especially severe or worsening lower right-sided abdominal pain, and seek medical attention immediately if one or more are present. 

What Causes Appendicitis?

A blockage in the appendix lumen (the inside area of the appendix that empties into the large intestine) is the primary cause of appendicitis.

The following factors or scenarios may cause this blockage:

  • A fecalith (a hard mass of stool)
  • Lymphoid hyperplasia (enlargement of the lymphatic tissue within the appendix)
  • Digestive tract infection (e.g., viral, bacterial, fungal, or parasitic) 
  • Cancerous or noncancerous growths within the appendix or large intestine
  • Appendicoliths (firm, tightly packed stool and mineral deposits in the appendix)
  • Trauma to the abdomen
  • Swallowed seeds of fruits, like oranges, melons, and grapes or foreign objects (very rare)

When the appendix lumen is blocked, the appendix becomes swollen, sore, and filled with pus.

What Is Pus?

Pus is a yellowish-white liquid made up of bacteria, dead white blood cells (infection-fighting cells), and tissue debris.

The swelling and pressure buildup within the inflamed appendix disturbs its blood supply. This can lead to necrosis (tissue death) and, eventually, rupture or bursting open of the appendix.

If the appendix ruptures, the leaked pus may form an abscess (pocket of pus/bacteria) around the appendix or spill more deeply into the abdomen, causing a life-threatening infection called peritonitis.

It's impossible to know whether or not an inflamed appendix will rupture—although the type of blockage may provide a clue. Limited research suggests that compared to other causes of blockages, like fecaliths, appendicoliths are more frequently associated with appendix rupture.

The following factors are common in people whose appendix ruptures:

  • Being a person older than 60 years
  • Having a fever higher than 99.1 degrees F
  • The presence of guarding on physical exam (when you tense your stomach muscles in anticipation of the healthcare provider placing pressure over the area of pain)
  • Having a high white blood cell count
  • Experiencing pain that lasts more than 24 hours

How Common Is Appendicitis?

In the United States, appendicitis is diagnosed in about 250,000 individuals yearly. It's most common in people aged 20 to 30 years.

Is Appendicitis Always a Medical Emergency?

Appendicitis is always a medical emergency. If not treated, an inflamed appendix can rupture and cause serious or potentially fatal complications like abscess or peritonitis.

Symptoms Before Appendicitis Rupture

Abdominal pain is the most common symptom of appendicitis. Pain is present in almost all cases of appendicitis.

It typically begins near the belly button before traveling to the lower right side of the abdomen. The pain may start as crampy and vague before gradually becoming sharper and severe within about 12 to 24 hours.

The pain's location, intensity, and whether or not it "travels" can vary depending on the anatomical location of a person's appendix and other factors, like age.

For example, with appendicitis in pregnancy, the pain may be experienced in the upper right side of the abdomen, as opposed to the lower right side. Likewise, in older individuals, the abdominal pain of appendicitis may remain mild and start in the lower right side of the abdomen instead of around the belly button.

In addition to abdominal pain, other symptoms of appendicitis include:

Symptoms After Appendicitis Rupture

If the appendix ruptures and a complication like peritonitis develops, symptoms and signs may include the following:

How to Diagnose Appendicitis

Healthcare providers look at several factors when deciding whether a person may have appendicitis (called risk stratification). They will take into account the patient's symptoms, results from a physical examination, and blood and imaging test results.

Unfortunately, appendicitis is a diagnosis that can be missed, especially when it presents with atypical signs and symptoms or the imaging isn't definitive. One known misdiagnosis is acute gastroenteritis (often called stomach flu), which can lead to delayed treatment and rupture.

Physical Exam

During the physical exam, the healthcare provider will gently press on your abdomen. Tenderness in the lower right side of your belly is a classic sign of appendicitis. Stiffness (rigidity) of your stomach muscles and guarding may also be present.

The healthcare provider may also perform a digital rectal examination. During the digital rectal exam, the healthcare provider inserts a gloved, lubricated finger into your rectum through your anus. Right-sided rectal tenderness supports a diagnosis of appendicitis.

A pelvic examination may be given to rule out mimicking gynecologic conditions.

Overlapping Symptoms

Symptoms of the following gynecologic diseases may resemble that seen with appendicitis:

Blood Tests

A white blood cell count and a C-reactive protein (CRP) level may be drawn when appendicitis is suspected. An elevated white blood cell count suggests infection in the body, whereas an elevated CRP suggests inflammation.

If a urinalysis is done, white blood cells may also be seen in the urine in acute appendicitis. This might lead to a misdiagnosis of a urinary tract infection.

Imaging Tests

An imaging test of the abdomen can help confirm a diagnosis of appendicitis. It can also help determine whether the appendix has ruptured and rule out alternative diagnoses. While imaging is very sensitive and specific, it can still miss cases.

The preferred diagnostic imaging test for adult appendicitis is an abdominal computed tomography (CT) scan (a special type of X-ray that creates a 3D image of the body).

The preferred imaging study for children or pregnant people is an abdominal ultrasound. There is no radiation exposure with ultrasound, as it uses sound waves to visualize structures within the body.

What Are the Most Common Treatments?

Appendectomy, or surgical appendix removal, is the standard treatment for appendicitis. This surgery is performed by a general surgeon under general anesthesia.

An appendectomy can be performed openly or laparoscopically, as follows:

  • Open surgery: The surgeon uses a scalpel to make a large incision (cut) below and to the right of your belly button. The appendix is removed through this large incision.
  • Laparoscopic surgery: The surgeon makes multiple small incisions in the abdomen. Long, thin instruments inserted through the small incisions are then used to remove the appendix.

Advantages of laparoscopic appendectomy include shorter recovery time and less pain and scarring. However, not everyone is a candidate for laparoscopic surgery.

Open surgery is recommended if your appendix is very inflamed or has ruptured. The presence of scar tissue from prior abdominal surgery is another additional indication for open surgery.

Surgery vs. Antibiotics

Antibiotics may be an alternative treatment option to surgery for appendicitis if the appendix has not ruptured and there is no evidence of abscess formation or peritonitis.

While there is no standard antibiotic regimen for appendicitis, most healthcare providers give antibiotics intravenously (within a vein) for a few days, followed by a week or more of oral (by mouth) antibiotics.

Recurrence After Antibiotics

While antibiotic therapy offers the benefits of a faster recovery, one drawback is that appendicitis can recur.

According to a 2018 study in JAMA (Journal of the American Medical Association), early 40% of people who received antibiotics for appendicitis developed recurrent appendicitis within five years.

Talk With Your Surgeon

If you have appendicitis and are a candidate for antibiotic therapy, review the potential risks and benefits with your surgeon. Don't hesitate to voice your wishes, questions, and concerns.

Recovery After Appendectomy

Recovery from an appendectomy often goes seamlessly and quickly, although the exact timing will depend on whether the surgery was open or laparoscopic.

If you underwent a laparoscopic appendectomy, you may stay in the hospital for one night or be discharged on the same day as the surgery. If you underwent open surgery, you might stay in the hospital for up to three days.

Pain in the abdomen and around the incision site(s) is common after surgery.

Once discharged from the recovery room or hospital, you will follow specific postoperative instructions about the following:  

  • Keeping your abdominal incision site(s) clean and dry
  • Taking your pain medication as directed
  • Timing on when you can resume activities (e.g., driving, working, and heavy lifting)
  • Following up with your surgeon


Appendicitis occurs when a tiny, finger-shaped organ attached to the colon becomes inflamed and infected. Its main symptom is severe abdominal pain that may be felt around the belly button before traveling to the lower right side of the abdomen.

A physical exam, blood tests, and an imaging test are used to assess people for possible appendicitis. Imaging is very sensitive and specific but can still miss cases. The standard treatment is surgery to remove the diseased appendix, although, in some cases, antibiotics alone are enough.

17 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Bhangu A, Søreide K, Di Saverio S, Assarsson JH, Drake FT. Acute appendicitis: modern understanding of pathogenesis, diagnosis, and management. Lancet. 2015;386(10000):1278-1287. doi:10.1016/S0140-6736(15)00275-5

  2. Engin O, Yildirim M, Yakan S, Coskun GA. Can fruit seeds and undigested plant residuals cause acute appendicitis. Asian Pac J Trop Biomed. 2011;1(2):99-101. doi:10.1016/S2221-1691(11)60004-X

  3. Kim JH, Lee DS, Kim KM. Acute appendicitis caused by foreign body ingestion. Ann Surg Treat Res. 2015;89(3):158-161. doi:10.4174/astr.2015.89.3.158

  4. Khan MS, Chaudhry MBH, Shahzad N, et al. The characteristics of appendicoliths associated with acute appendicitis. Cureus. 2019;11(8):e5322. doi:10.7759/cureus.5322

  5. Prachanukool T, Yuksen C, Tienpratarn W, et al. Clinical prediction score for ruptured appendicitis in ED. Emerg Med Int. 2021;2021:6947952. doi:10.1155/2021/6947952

  6. Walter K. Acute appendicitis. JAMA. 2021;326(22):2339. doi:10.1001/jama.2021.20410

  7. Jacobs DO. Acute appendicitis and peritonitis. Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J (Eds.), Harrison's Principles of Internal Medicine, 19e. McGraw Hill. 2014.

  8. Snyder MJ, Guthrie M, Cagle S. Acute appendicitis: efficient diagnosis and management. Am Fam Physician. 2018;98(1):25-33.

  9. Mahajan P, Basu T, Pai CW, et al. Factors associated with potentially missed diagnosis of appendicitis in the emergency department. JAMA Netw Open. 2020;3(3):e200612. doi:10.1001/jamanetworkopen.2020.0612

  10. Takada T, Nishiwaki H, Yamamoto Y, et al. The role of digital rectal examination for diagnosis of acute appendicitis: a systematic review and meta-analysis. PLoS One. 2015;10(9):e0136996. doi:10.1371/journal.pone.0136996

  11. MedlinePlus. Appendectomy - series- indications.

  12. Amer E. Mimickers of acute appendicitis. In: Guttadauro A, ed. Doubts, Problems and Certainties about Acute Appendicitis. IntechOpen; 2022. doi:10.5772/intechopen.96351

  13. Gupta AK, Mann A, Belizon A. Appendicitis caused by endometriosis within the bowel wall. Cureus. 2020;12(8):e9614. doi:10.7759/cureus.9614

  14. Rud B, Vejborg TS, Rappeport ED, Reitsma JB, Wille-Jørgensen P. Computed tomography for diagnosis of acute appendicitis in adults. Cochrane Database Syst Rev. 2019;2019(11):CD009977. doi:10.1002/14651858.CD009977.pub2

  15. SAGES: Society of American Gastrointestinal and Endoscopic Surgeons. Appendix removal (appendectomy) surgery patient information from SAGES.

  16. Harnoss JC, Zelienka I, Probst P, et al. Antibiotics versus surgical therapy for uncomplicated appendicitis: systematic review and meta-analysis of controlled trials (PROSPERO 2015: CRD42015016882). Ann Surg. 2017;265(5):889-900. doi:10.1097/SLA.0000000000002039

  17. Salminen P, Tuominen R, Paajanen H, et al. Five-year follow-up of antibiotic therapy for uncomplicated acute appendicitis in the APPAC randomized clinical trial. JAMA. 2018;320(12):1259-1265. doi:10.1001/jama.2018.13201

Colleen Doherty, MD

By Colleen Doherty, MD
Dr. Doherty is a board-certified internist and writer living with multiple sclerosis. She is based in Chicago.