Acute Appendicitis

Appendicitis is inflammation of the appendix, a small, tubular organ in the right lower abdomen that is attached to the large intestine.

Common causes of acute appendicitis include infections, tumors, or accumulation of calcified feces (appendicolith) in the appendix. The most common symptom of acute appendicitis is pain in the right lower abdomen. More than half of patients first experience discomfort in the midabdominal area, which later becomes more localized to the right lower abdominal area. Other symptoms include loss of appetite, nausea, vomiting, and low-grade fever.

Acute appendicitis is diagnosed in about 250 000 people each year in the US and is most common among people 20 to 30 years old. Approximately 8.6% of men and 6.7% of women in the US are diagnosed with appendicitis over their lifetimes.

Acute appendicitis is defined as uncomplicated if the appendix has not ruptured. Complicated appendicitis occurs when the appendix ruptures, resulting in a widespread infection in the abdomen (peritonitis) or a contained pocket of pus in the abdomen. Men and older adults are at higher risk of developing complicated appendicitis.

Diagnosis of acute appendicitis is made based on a patient’s history, physical examination, laboratory values (such as a high white blood cell count), and imaging. In the US, computed tomography (CT) of the abdomen is the most common form of imaging used to diagnose acute appendicitis. Abdominal ultrasound may also be used and is helpful to avoid radiation exposure in children and pregnant people. However, the appendix may be challenging to see on ultrasound in patients with obesity or pregnancy.

The most common treatment for acute uncomplicated appendicitis is laparoscopic appendectomy, which is a minimally invasive surgery performed through 3 small incisions to remove the entire appendix. Instead of surgery, some adults (and less commonly, children) with uncomplicated acute appendicitis may be successfully treated with a 10-day course of broad-spectrum antibiotics. In patients treated with antibiotics, rates of recurrent appendicitis within 1 year range from 15% to 41%. Important factors for determining the best treatment option for patients with acute uncomplicated appendicitis are presence of high-risk CT findings that make antibiotics less effective (such as presence of an appendicolith or a dilated appendix), the risk of surgery for an individual patient, and patient preference.

Patients with complicated appendicitis who are severely ill because of the infection (sepsis) need antibiotics and emergency surgery to remove the appendix. Those who are not acutely ill but have contained pockets of pus in the abdomen typically require intravenous antibiotics, placement of a drain into the abdomen to remove the pus, and evaluation for appendectomy 6 to 8 weeks later.

Conflict of Interest Disclosures: None reported.

Source: Moris D, Paulson EK, Pappas TN. Diagnosis and management of acute appendicitis in adults: a review. JAMA. Published December 14, 2021. doi:10.1001/jama.2021.20502