Appendicitis is inflammation of the appendix, a small finger-shaped pouch attached to the large intestine in your lower right abdomen. It’s one of the most common reasons for emergency abdominal surgery, and it typically develops quickly, progressing from vague belly pain to a surgical situation within 24 to 72 hours.
What the Appendix Actually Does
The appendix sits where the small intestine meets the large intestine, near a structure called the cecum. For a long time it was considered a useless evolutionary leftover, but that view has shifted. The appendix contains immune tissue that helps produce antibodies and mature certain immune cells. It also appears to serve as a reservoir for beneficial gut bacteria. When severe diarrhea or illness wipes out the normal bacteria in your intestines, the appendix can reseed them with a backup supply. That said, people live perfectly normal lives without one.
What Causes Appendicitis
The classic explanation is that something blocks the narrow opening of the appendix. In children, the most common culprit is swollen lymph tissue inside the appendix wall, often triggered by a viral or bacterial infection. In adults, a small hardened piece of stool (called a fecalith) is the typical offender. Less commonly, parasites, tumors, or scar tissue can create the blockage.
Once blocked, bacteria multiply inside the trapped space, the appendix swells, and pressure builds. If left untreated, the wall can weaken and eventually rupture, spilling infectious material into the abdominal cavity. Not every case follows this exact pattern, though. Some researchers have argued that bacterial infection alone, without any blockage, can trigger the inflammation. Diet, genetics, and constipation have also been proposed as contributing factors.
How the Pain Develops
Appendicitis has a distinctive pain pattern that sets it apart from most other causes of stomach pain. It usually starts as a dull, vague ache around your belly button. This pain may hover or come and go for several hours. During this early phase, nausea and vomiting often develop.
Then the pain shifts. Over the next several hours, it migrates to your lower right abdomen, becomes sharper and more focused, and steadily worsens. At this point, walking, coughing, or even riding over a bump in the car can intensify it. You may also notice a low-grade fever, loss of appetite, and a sense that something is clearly wrong. Not everyone follows this textbook progression, especially young children, pregnant women, and older adults, whose symptoms can be more subtle or atypical.
How Appendicitis Is Diagnosed
Doctors rely on a combination of your symptom history, a physical exam, blood work, and imaging. During the exam, they’ll press on a spot about one-third of the way from your right hip bone to your belly button, known as McBurney’s point. Sharp tenderness there is one of the strongest clinical indicators. They may also check for “rebound tenderness,” where the pain spikes when pressure is suddenly released rather than when it’s applied.
A few other physical tests can help. Pressing on the left side of your abdomen may produce pain on the right side (by pushing trapped air toward the inflamed appendix). If the appendix sits near certain hip muscles, extending or rotating your leg may reproduce the pain. None of these tests alone is definitive. Each has relatively low sensitivity, catching only about 16 to 27 percent of cases, but high specificity, meaning a positive result makes appendicitis quite likely.
Imaging usually confirms the diagnosis. CT scans are the gold standard in adults, with a sensitivity of about 97% and specificity of 96%. When both IV and oral contrast are used, those numbers climb even higher, to roughly 99% sensitivity and 97% specificity. Low-dose CT scans, which reduce radiation exposure, perform comparably to standard-dose scans. Ultrasound is the preferred first choice for children and pregnant women because it avoids radiation, though it’s less accurate overall, with sensitivity around 82% and specificity around 86%.
Clinicians also use scoring systems to gauge risk. The Alvarado score assigns points based on eight factors: pain migration to the lower right abdomen, loss of appetite, nausea or vomiting, tenderness in the lower right abdomen, rebound pain, fever, elevated white blood cell count, and a shift in the types of white blood cells present. A high score pushes the clinical suspicion strongly toward appendicitis and helps determine how urgently imaging or surgery is needed.
Surgery: Laparoscopic vs. Open
Appendectomy, the surgical removal of the appendix, remains the standard treatment. There are two approaches. Laparoscopic surgery uses three small incisions, each about 1 centimeter (roughly half an inch). Open surgery uses a single larger incision of about 5 centimeters (2 inches) in the lower right abdomen. Most appendectomies today are performed laparoscopically.
The differences in recovery are meaningful. Adults who have laparoscopic surgery spend about one fewer day in the hospital and return to normal activity roughly five days sooner than those who have open surgery. Wound infections are also significantly less common after laparoscopic surgery, occurring at less than half the rate. The one trade-off in adults is a slightly higher risk of internal abscesses forming after laparoscopic surgery, though this remains uncommon overall.
In children, laparoscopic surgery offers a similar advantage: shorter hospital stays by about 0.8 days, a 75% reduction in wound infections, and no significant increase in internal abscesses.
Antibiotics Without Surgery
For uncomplicated appendicitis (no rupture, no abscess, no hardened stool blockage visible on imaging), antibiotics alone have become a legitimate option. The landmark CODA trial tracked patients who chose antibiotics instead of surgery and found that 71% avoided the operating room through the first 90 days. By one year, however, 40% had eventually needed surgery. By two years, that number rose to 46%, and by three to four years, roughly half had ultimately undergone appendectomy.
The presence of a fecalith matters significantly. Patients whose imaging showed a hardened stool fragment had a 61% chance of eventually needing surgery within three to four years, compared to 44% for those without one. This means antibiotics work best as a long-term solution for people with uncomplicated appendicitis and no visible blockage. For the rest, antibiotics may buy time but are less likely to be a permanent fix.
What Recovery Looks Like
After a laparoscopic appendectomy, most people return to work or school within one to three weeks. Open surgery extends that timeline to up to a month. Full recovery, meaning no restrictions on exercise or heavy lifting, takes about six weeks regardless of the surgical approach.
In the early days, you’ll want to eat soft foods until your digestive system adjusts. Walking short distances soon after surgery is important for preventing blood clots and getting your bowels moving again, but stair climbing and lifting heavy objects should wait. After open surgery, standing for long periods may cause your abdominal muscles to ache. The goal during the first few weeks is gentle, gradual activity, not rest in bed.
What Happens if the Appendix Ruptures
A ruptured appendix is the main complication doctors are trying to prevent. When the appendix bursts, bacteria flood the abdominal cavity, causing a serious infection called peritonitis. This can also lead to the formation of abscesses, pockets of pus that may need to be drained separately. A rupture typically makes the surgery more complex, extends the hospital stay, and requires a longer course of antibiotics afterward. The risk of rupture increases the longer appendicitis goes untreated, which is why the condition is treated as urgent once diagnosed.