Appendicitis is inflammation of the appendix, a small finger‑shaped pouch attached to the large intestine in the lower‑right abdomen; it most commonly causes sudden, worsening abdominal pain and is the leading reason for urgent abdominal surgery.
What is an appendicitis?
Appendicitis is an acute inflammation of the appendix, a narrow, blind-ended tubular structure attached to the cecum in the lower right abdomen. It usually begins when the appendix lumen becomes obstructed by fecal material, lymphoid hyperplasia, foreign bodies, or, less commonly, a tumor, which leads to trapped secretions, bacterial overgrowth, increasing intraluminal pressure, compromised blood flow, and progressive tissue injury. The clinical course typically starts with vague, periumbilical or epigastric pain that migrates over hours to the right lower quadrant, accompanied by anorexia, nausea, vomiting, low-grade fever, and localized tenderness; atypical presentations are common in children, older adults, and pregnant patients. Left untreated, the inflamed appendix may perforate, releasing infected material into the peritoneal cavity and causing peritonitis, abscess formation, systemic infection, and sepsis. Diagnosis is based on clinical assessment supported by laboratory tests showing leukocytosis and inflammatory markers, and by imaging—ultrasound is preferred in children and pregnancy while CT provides higher accuracy in adults. Definitive management is surgical removal of the appendix (appendectomy), often combined with perioperative antibiotics; in selected uncomplicated cases, antibiotics alone can be considered. Early recognition and treatment significantly reduce morbidity and mortality.
What are the symptoms & causes of appendicitis?
Appendicitis is an inflammation of the appendix that typically begins with vague, central abdominal discomfort that evolves over hours into sharper pain localized to the right lower abdomen, often accompanied by loss of appetite, nausea, vomiting, and low‑grade fever; pain usually worsens with movement, coughing, or jarring and may be associated with constipation or diarrhea and abdominal bloating. Early presentations can be atypical in children, older adults, and pregnant people, who may not develop the classic localized pain. The common initiating event is obstruction of the appendix lumen by fecal material, lymphoid hyperplasia, foreign bodies, parasites, or rarely a tumor; obstruction traps secretions, promotes bacterial overgrowth, increases intraluminal pressure, impairs blood flow, and leads to ischemia, inflammation, and possible perforation. Lymphoid hyperplasia after viral infection, hardened fecaliths (appendicoliths), and local intestinal inflammation such as colitis are frequent contributors. If untreated, progressive inflammation can cause rupture, peritonitis, abscess formation, and systemic infection, which is why timely clinical evaluation and treatment—usually surgical removal or, in selected cases, antibiotics—is important.
What other conditions might be confused with appendicitis?
Many abdominal and pelvic disorders can mimic appendicitis because they produce similar right lower quadrant pain, nausea, fever, and tenderness. Gastroenteritis and ileitis, including infectious causes such as Yersinia or Campylobacter, often present with diffuse abdominal pain, diarrhea, and systemic symptoms that can be mistaken for early appendicitis. Mesenteric adenitis produces tender lymphadenopathy and central-to-right abdominal pain, especially in children. Gynecologic conditions in women — ovarian torsion, ruptured ovarian cyst, tubo-ovarian abscess, and ectopic pregnancy — can produce acute unilateral pain and constitutional symptoms overlapping with appendicitis. Urologic problems such as ureteric or kidney stones and acute epididymitis can radiate pain to the lower abdomen and groin. Bowel-related causes include right-sided diverticulitis, Crohn disease with terminal ileitis, and severe constipation. Less common mimics include epiploic appendagitis, Meckel diverticulitis, perforated peptic ulcer with localized peritonitis, and diabetic ketoacidosis presenting with abdominal pain. Postoperative adhesions, hernias, and abdominal wall pathology such as rectus sheath hematoma may also resemble appendiceal pain. Because many of these conditions require very different management, careful history, pregnancy testing when relevant, focused exam, laboratory tests, and appropriate imaging are essential to distinguish appendicitis from its mimics.
How is appendicitis diagnosed?
Diagnosis of appendicitis begins with a careful clinical assessment of history and physical examination, where classic features include periumbilical pain that migrates to the right lower quadrant, anorexia, nausea or vomiting, and low-grade fever; examination may reveal localized tenderness, guarding, and rebound tenderness suggesting peritoneal irritation. Initial laboratory testing commonly includes a complete blood count and inflammatory markers to detect leukocytosis or elevated C-reactive protein, and a urinalysis to exclude urinary tract causes; pregnancy testing and pelvic examination are essential in women of reproductive age to rule out gynecologic mimics. Imaging is used when the diagnosis is uncertain or to assess complications: graded-compression abdominal ultrasound is often the first-line modality in children and pregnant patients because it avoids ionizing radiation, while contrast-enhanced CT of the abdomen and pelvis provides higher diagnostic accuracy in adults and better delineation of abscess, perforation, or alternative diagnoses. In select situations MRI may be used as an alternative to CT. Clinical scoring systems and shared decision-making with surgical teams help determine whether observation, antibiotics, or urgent appendectomy is appropriate, and in most centers a combination of clinical evaluation, labs, and imaging achieves high diagnostic accuracy.
What are the treatments for appendicitis?
Treatment for appendicitis depends on severity and complications but commonly involves prompt surgical removal of the appendix (appendectomy) combined with antibiotics; appendectomy can be performed laparoscopically through several small incisions, which usually leads to faster recovery and less pain, or by an open incision when the appendix has ruptured or when widespread infection requires more extensive cleaning of the abdominal cavity. Before surgery patients typically receive intravenous fluids and broad‑spectrum antibiotics to reduce infection risk, and if an abscess has formed the initial management may include percutaneous drainage with a catheter followed by delayed appendectomy once inflammation is controlled. In selected cases of uncomplicated appendicitis, nonoperative management with antibiotics alone is an evidence‑based option that can resolve symptoms and avoid immediate surgery for some patients, though it carries a higher risk of recurrence and may require later appendectomy. Choice of therapy should take into account patient age, pregnancy status, imaging findings, comorbidities, and shared decision‑making with surgical teams; timely treatment reduces risk of perforation, peritonitis, prolonged hospitalization, and sepsis.
Conclusion
Appendicitis is a common but potentially serious inflammation of the appendix that typically presents with migrating abdominal pain, nausea, and fever and requires timely evaluation to prevent rupture and widespread infection. Early recognition using clinical assessment supported by laboratory tests and imaging allows prompt treatment, most often surgical removal of the appendix, while selected uncomplicated cases may be managed with antibiotics under close follow-up. Delayed or missed diagnosis increases the risk of perforation, abscess, prolonged hospitalization, and sepsis, so clinicians must maintain a low threshold for investigation when signs suggest appendicitis.
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