- Appendicitis affects approximately 300,000 patients/year and consumes over 1 million hospital days in the US. Lifetime risk is 8.6% for males and 6.7% for females. In 2005, patients with abdominal pain composed 6.8%
of 115 million annual emergency department visits.
- Appendicitis typically begins with luminal obstruction from inspissated fecal matter or lymphoid hyperplasia and progresses to perforation at a rate of approximately 5-10%/24 hours after the first 24 hours.
- In young, preverbal toddlers, the risk of perforation at the time of appendicitis diagnosis is high. In children younger than 4 years, appendiceal perforation occurs in the vast majority of cases, with rates reported as high as 80% to 100%. In contrast, appendicitis in children aged 10 to 17 years is more common, but the perforation rate is much lower (10%-20%).
- Appendicitis is generally diagnosed by a constellation of history and physical exam findings and limited laboratory evaluations.
- Diagnostic imaging is used to confirm the diagnosis in most women and children, and frequently in men as well.
- Most patients with acute appendicitis can be safely managed with laparoscopic or open appendectomy.
- Selected patients with periappendiceal abscess or phlegmon, and selected patients with acute, nonperforated appendicitis can be safely managed nonoperatively with antimicrobial therapy alone.
- Antimicrobial therapy is important in preventing the complications of acute appendicitis, including both surgical site infections and deep organ space abscesses.
- Antimicrobial therapy should be initiated preoperatively in all patients undergoing operative appendectomy. Antimicrobial therapy should be discontinued within 24 hours in patients with acute, nonperforated appendicitis.
- Patients with perforated appendicitis and patients being managed nonoperatively should receive antimicrobial therapy according to the general principles outlined for management of patients with complicated intra-abdominal infection.
Assessment and Diagnosis
- Key findings for appendicitis obtained from the history, physical examination and white blood cell count are listed in Table 1.
- The physical exam should include auscultation of the lungs, palpation of the abdomen beginning away from the right lower quadrant, and pelvic examination in women.
- Pain caused by physical examination is to be avoided by using gentle palpation and looking for localized muscular rigidity. In some cases small doses of narcotics may facilitate the exam.
- Clinical findings serve to risk-stratify patients and guide decisions about further testing and management. The Alvarado score captures pertinent findings for stratifying patients by probability of disease.
- The Alvarado Scoring System was developed and calibrated on individuals ≥ 16 years of age. It provides probabilities for the presence of appendicitis. Its sensitivity and specificity are inadequate for therapeutic decision-making. It is useful in focusing attention on key signs and symptoms. It may also provide data for local practice audits.
- The Alvarado score is not valid for patients with a palpable mass in the right lower quadrant or with evidence of generalized peritonitis. It is also not useful in patients with sensory impairment due to an acute confusional state, dementia or some other cause.
- Scores < 5 suggest that the diagnosis of appendicitis is unlikely. Scores of 5 or 6 suggest appendicitis is a possible diagnosis. Scores of 7 or higher support the diagnosis of acute appendicitis.
Table 1. The Alvarado Score (Mnemonic for the diagnostic score of acute appendicitis: MANTRELS)
|Signs||Tenderness in right lower quadrant|
Elevation of temperature
Shift to the left
- Based upon the patient’s age, history and physical findings, the surgeon may choose, with high sensitivity and specificity, to operate immediately or to exclude the diagnosis of appendicitis without further diagnostic studies.
- CT scanning is the initial imaging modality of choice for suspected appendicitis in adult males and non-pregnant females (B-II).
- The CT findings suggestive of appendicitis include greater than 6 mm wall thickening; right lower quadrant inflammatory changes, such as fat stranding; and the presence of appendicoliths.
- All females should undergo diagnostic imaging. Those of childbearing potential should undergo pregnancy testing prior to imaging, and if in the first trimester of pregnancy should undergo ultrasound or magnetic resonance rather than exposure to ionizing radiation (B-II). If these studies do not define the pathology present, laparoscopy or limited CT scanning may be considered (B-III).
- Imaging of all children (particularly those under 3 years of age) is performed when the diagnosis of appendicitis is less than certain. For children, CT imaging is preferred although ultrasound may be used to avoid ionizing radiation (B-III).
- For patients with negative imaging studies for suspected appendicitis, clinical follow-up at 24 hours is recommended to ensure resolution of signs and symptoms, because of the low but measurable risk of false negatives (B-III).
- For patients with suspected appendicitis that can neither be confirmed nor excluded by diagnostic imaging, careful follow-up is recommended. Such patients may be hospitalized if the index of suspicion is high (A-III).