Key History

Key Physical Exam

Differential Diagnosis

Diagnostic Testing

Labs: When clinicians have a low pretest probability for appendicitis, the combination of a WBC count < 10,000/ mm3 and CRP < 8 mg/ L support the exclusion of appendicitis as a likely diagnosis.

• WBC count – May be elevated or normal; a higher white count is associated with perforation.
• C-reactive protein (CRP)
• Urinalysis may show hematuria or pyuria – found in up to 1/3 of patients with appendicitis
• B-hCG mandatory to rule out an ectopic pregnancy in females of childbearing age

Imaging: Obtain early surgical consultation before imaging in straightforward cases of suspected appendicitis in adults. Imaging is not universally necessary but may be of benefit to certain populations.

• KUB. Plain radiography is generally not helpful. Findings are typically nonspecific. An appendicolith may be visualized in up to 50% of children with appendicitis.
• Graded Compression Ultrasound. Ultrasound should be the initial imaging modality of choice in both pregnant females and children. It can similarly be considered in young, nonobese adults (typical findings in appendicitis are a thickened, noncompressible appendix > 6 mm in diameter). A meta-analysis by Doria et al. lists the overall sensitivity of ultrasound as 88% and 83% and its specificity as 94% and 93% for children and adults, respectively.
• Noncontrast CT. Unenhanced, noncontrast abdominopelvic CT should be considered an acceptable imaging modality in the workup of acute appendicitis. There is controversy over the use of IV and oral contrast. Many centers continue to use one or both. CT demonstrates higher diagnostic accuracy than ultrasound or MRI. The disadvantage is the exposure to ionizing radiation.
• MRI. MRI may be considered as another reliable imaging technology in the evaluation of acute appendicitis, particularly in pregnant women.

Clinical Risk and Safety Pearls

• Abdominal pain usually occurs before nausea and vomiting, unlike gastroenteritis, where nausea and vomiting usually occur first.
• Serial evaluations over several hours may improve diagnostic accuracy in patients with an atypical presentation.
• The presence of appendicitis is not always apparent on the initial visit. Evaluate and re-evaluate. Document carefully. Demonstrate high-quality care and that the diagnosis was simply not apparent during your evaluation.
• The urinalysis may show hematuria or pyuria, which is present in up to 1/3 of patients with appendicitis.
• Order a β-hCG to rule out an ectopic pregnancy in females of childbearing age.
• Taking a history of symptoms immediately prior to onset of pain is helpful in determining diagnosis.
• Early in the presentation, the abdominal exam may be unremarkable.

Pregnancy and Appendicitis

Treatment

• Nonoperative management of acute appendicitis (IV antibiotics, admission) is gaining support. The patient should not have high-risk features on imaging (e.g., presence of a fecalith, abscess, tumor, fluid collection, or appendiceal diameter > 1.1 cm) and should be made aware of the risks of treatment failure and recurrent appendicitis, both of which generally require surgical removal of the appendix.
• IV hydration
• Pain medication. Opiate analgesia does not limit abdominal examination for a potential surgical condition.
• When present, nausea can be treated with parenteral antiemetics.
• Antibiotics should cover gram-negative aerobes, enteric gram-positive streptococci, and anaerobes. Pseudomonal coverage is not necessary for patients with mild to moderate disease severity and lack of healthcare–associated risk factors.

ACEP Policy

1. In adult patients, because of insufficient data, ACEP recommends not using clinical prediction rules to identify patients for home; no advanced imaging is required. In pediatric patients, clinical prediction rules can be used to rule stratify for possible acute appendicitis. However, ACEP recommends not using clinical prediction rules alone to identify patients who do not warrant advanced imaging for the diagnosis of appendicitis (Level B Recommendation).
2. In pediatric patients with suspected acute appendicitis, if readily available and reliable, use right lower quadrant ultrasound to diagnose appendicitis. An unequivocally positive right lower quadrant ultrasound with complete visualization of a dilated appendix has comparable accuracy to a positive CT or MRI in pediatric patients (Level B Recommendation).
3. In adult patients with suspected acute appendicitis, an unequivocally positive right lower quadrant ultrasound has comparable accuracy to a positive CT or MRI for ruling out appendicitis.