What are the causes of appendicitis?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: March 31, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

Appendicitis is primarily caused by a blockage of the appendix lumen, which can lead to increased pressure, impaired blood flow, and inflammation, ultimately resulting in morbidity and mortality if not treated promptly. The blockage is typically caused by a fecalith, lymphoid hyperplasia, or less commonly by foreign bodies, parasites, or tumors 1. This blockage leads to increased pressure within the appendix, impaired blood flow, bacterial overgrowth, and inflammation. As bacteria multiply in the trapped space, the appendix becomes inflamed and filled with pus. Without treatment, the appendix can rupture, spreading infection throughout the abdomen (peritonitis), which is associated with increased morbidity and mortality compared with non-perforating acute appendicitis 1.

The clinical presentation of appendicitis is often challenging to diagnose and involves a synthesis of clinical, laboratory, and radiological findings. The diagnostic workup could be improved by using clinical scoring systems that involve physical examination findings and inflammatory markers 1. Key risk factors for appendicitis include age, with a peak incidence in teens and young adults, family history, and diets low in fiber. Geographical differences are also reported, with a lifetime risk for acute appendicitis of 9% in the USA, 8% in Europe, and 2% in Africa 1.

The progression of appendicitis typically begins with obstruction, followed by increased pressure, bacterial invasion, inflammation, and potentially perforation within 24-72 hours if untreated. This explains why appendicitis typically presents as periumbilical pain that migrates to the right lower quadrant, accompanied by fever, nausea, and loss of appetite. Laparoscopic appendectomy is currently the most effective surgical treatment, being associated with a lower incidence of wound infection and post-intervention morbidity, shorter hospital stay, and better quality of life scores when compared to open appendectomy 1.

From the Research

Appendicitis Causes and Treatment

  • Appendicitis is a common abdominal surgical emergency with an annual incidence of 96.5 to 100 cases per 100,000 adults 2.
  • The clinical diagnosis of acute appendicitis is based on history, physical examination, laboratory evaluation, and imaging 2.
  • Classic symptoms of appendicitis include vague periumbilical pain, anorexia/nausea/intermittent vomiting, migration of pain to the right lower quadrant, and low-grade fever 2.

Treatment Options

  • Laparoscopic appendectomy remains the most common treatment for acute appendicitis 2.
  • Broad-spectrum antibiotics, such as piperacillin-tazobactam monotherapy or combination therapy with either cephalosporins or fluroquinolones with metronidazole, can successfully treat uncomplicated acute appendicitis in approximately 70% of patients 2, 3.
  • Antibiotic treatment can be offered as the first-line therapy to a majority of unselected patients with acute appendicitis without medical drawbacks other than the unknown risk for long-term relapse 3.

Antibiotic Management

  • Recent studies have shown that narrow-spectrum antibiotics, such as ceftriaxone with metronidazole, can be effective in preventing surgical site infections in children with uncomplicated appendicitis 4, 5.
  • A quality improvement study found that updating electronic health record orders to encourage preoperative administration of narrow-spectrum antibiotics and educating surgeons and emergency department clinicians about selecting appropriate antibiotic therapy for acute appendicitis can decrease the treatment of uncomplicated acute appendicitis with piperacillin-tazobactam without increasing the rate of surgical site infections 6.

Complications and Outcomes

  • The rate of surgical site infections was similar in patients who received preoperative piperacillin-tazobactam and those who received narrow-spectrum antibiotics 6.
  • Postoperative use of piperacillin/tazobactam for complicated appendicitis is associated with higher rates of readmissions and intraabdominal abscess when compared to ceftriaxone with metronidazole 4.
  • Ceftriaxone combined with metronidazole is superior to cefoxitin alone in preventing surgical site infections in children with uncomplicated appendicitis 5.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.