Appendicitis: overview, causes, symptoms, diagnosis and treatment

Causes and risk factors

Appendicitis most often begins when the lumen of the appendix becomes obstructed. Obstruction may follow fecal material, lymphoid hyperplasia, foreign bodies, or parasites and can lead to bacterial overgrowth and invasion. Common proximal causes invoked in clinical discussion include mechanical blockage and bacterial infections. Risk is highest in older children and young adults, though cases occur at any age. Severe presentations are more frequent among very young children and the elderly. Rarely, blockages or trauma contribute to the condition.

Symptoms and diagnosis

The characteristic early symptoms are abdominal discomfort that shifts and intensifies, plus systemic and gastrointestinal signs such as nausea, vomiting and reduced appetite. Fever, elevated white blood cell count and tenderness on physical examination are common findings. Because nearly 40% of people may not show typical features, clinicians combine history, examination and imaging—usually ultrasound or computed tomography—to confirm the diagnosis. Differential diagnoses to consider include gynecologic conditions, urinary tract problems and other causes of acute abdominal pain encountered in medicine and surgery.

Treatment and complications

Treatment aims to remove the inflamed appendix or control infection. The standard definitive therapy is appendectomy, performed as an open or laparoscopic operation. In selected uncomplicated cases, particularly when diagnosed early, a course of antibiotics alone may resolve inflammation without surgery, though surgery remains common. If rupture occurs, management includes broad-spectrum antibiotics, drainage of abscesses when present and supportive care to prevent shock and systemic complications.

• Typical interventions: laparoscopic appendectomy, open appendectomy, or nonoperative antibiotic therapy.
• Possible complications: perforation, intra-abdominal abscess, peritonitis, sepsis and prolonged recovery.

Function of the appendix and historical notes

The role of the appendix in humans is debated. In some mammals the structure aids in the digestion of plant material; in humans it is smaller and may have immunological roles, such as contributing to mucosal immune responses and serving as a reservoir for beneficial gut bacteria. Elements of this immune contribution are sometimes discussed in relation to the immune system, but the appendix is not essential for survival.

Acute appendicitis was first clearly described in the late 19th century by Reginald Fitz. It remains one of the most frequent surgical emergencies worldwide. When someone has progressive abdominal pain or persistent gastrointestinal symptoms, prompt medical assessment reduces the risk of rupture and serious sequelae—do not delay seeking care when appendicitis is suspected.

For further clinical guidelines, imaging choices, and perioperative care practices, see specialist resources: inflammation overview, appendix anatomy, localizing abdominal pain, nausea causes, vomiting considerations, peritonitis management, sepsis guidance, digestive function, immune interactions, bacterial causes, shock prevention, appendectomy techniques, medical perspective, surgical perspective.