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Potentially life-threatening emergency
Acute appendicitis
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Potentially life-threatening emergency

Acute appendicitis

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Contributors: Michael W. Winter MD, Nishant H. Patel MD, Desiree Rivera-Nieves MD, Khaled Bittar MD
Other Resources UpToDate PubMed

Synopsis

Acute appendicitis occurs when the appendix becomes inflamed. The extent of the inflammation progresses through the endothelial wall, leading to focal ischemia, tissue necrosis, and, in some instances, perforation, which may be complicated by generalized peritonitis and abscess formation.

Acute appendicitis can occur at any age, but most commonly presents in the second and third decade of life. Lifetime incidence is 8.6% in males, 6.7% in females.

Appendicitis results from an obstruction of the appendiceal orifice, which can be caused by a fecalith, lymphoid hyperplasia, infection, calculi, or malignancy. Lymphoid hyperplasia is a more common etiology in younger patients, especially pediatrics.

The hallmark symptoms of appendicitis are anorexia, nausea and emesis, and abdominal pain that radiates or settles in the right lower quadrant (RLQ).

A retrocecal appendicitis may present with dull abdominal pain for a longer duration and may not localize to the RLQ. A positive psoas sign (RLQ pain with passive right hip extension) is more common with this presentation.

Pediatric Patient Considerations:
  • Neonates – appendicitis is rare but serious. The most common findings are abdominal distension and/or tenderness, emesis, and poor feeding. Other common findings include lethargy and irritability. There may be delay to diagnosis. Patients may develop sepsis, temperature instability, and dyspnea.
  • Young children – appendicitis is infrequent in this population but can occur. The most common findings are abdominal pain (including rebound tenderness and abdominal guarding), fever, and vomiting and anorexia. Diarrhea may occur. The abdomen may or may not be extended. Patients may resist walking or moving about.
  • School-age children – appendicitis is more common than in neonates, infants, and young children. Abdominal pain (often right lower quadrant), vomiting, anorexia, and fever are common presenting symptoms. Diarrhea is less frequent than in younger children. Patients may have difficulty walking.
  • Adolescents – findings are similar to those of adults with appendicitis.

Codes

ICD10CM:
K35.80 – Unspecified acute appendicitis

SNOMEDCT:
85189001 – Acute appendicitis

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Last Reviewed: 11/28/2016
Last Updated: 12/14/2018
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Potentially life-threatening emergency
Acute appendicitis
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Acute appendicitis (Adult) : Abdominal pain, Nausea, Vomiting, Anorexia, CRP elevated, RLQ pain, WBC elevated
Imaging Studies image of Acute appendicitis
Contrast enhanced axial image from CT scan demonstrating distended appendix with appendicolith.
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