Nonoperative Antibiotic Treatment of Acute Appendicitis

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Posted by Carla Rothaus

How often is appendectomy subsequently performed when acute uncomplicated appendicitis is treated nonoperatively?

Patients with acute, localized, uncomplicated appendicitis (approximately 80% of all appendicitis cases) are candidates for appendectomy or nonoperative treatment. Read the NEJM Clinical Practice Article here.

Clinical Pearls

Q: Do nonoperative outcomes for acute uncomplicated appendicitis differ in patients with versus without appendicolith?

A: Patients with imaging-identified appendicolith (which is present in approximately 25% of patients and is associated with appendiceal rupture) are at increased risk for complications such as abscess and undergo appendectomy more frequently than patients without appendicolith.

Q: What is the effect of diagnostic delay when patients with appendiceal cancer that causes or mimics appendicitis are managed with antibiotics?

A: In rare instances, cancer may cause appendicitis or symptoms mimicking appendicitis, or it may be found incidentally on appendectomy. In a study of 21,069 appendectomy specimens, researchers detected cancer in 0.9%, with a lower incidence of detection among persons younger than 50 years of age and among those with uncomplicated appendicitis. Thus, nonoperative treatment carries a small risk of delayed diagnosis and disease progression; data are lacking to inform the effect of diagnostic delay on patient outcomes.


Morning Report Questions

Q: How often is appendectomy subsequently performed when acute uncomplicated appendicitis is treated nonoperatively?

A: The percentage of patients who undergo appendectomy after initially receiving treatment with antibiotics varies depending on the patient population and the duration of follow-up. In the Finnish trial Appendicitis Acuta, 94% of the patients with appendicitis who received antibiotics improved during initial hospitalization, and 27% underwent appendectomy within 1 year. In the Midwest Pediatric Surgery Consortium study, the initial frequency of response was 86%, and 33% of the children underwent appendectomy at 1 year. In the Comparison of the Outcomes of Antibiotic Drugs and Appendectomy trial, among participants who received antibiotics, those without appendicolith had an initial response rate of 92% and those with appendicolith had an initial response rate of 78%. Appendectomy rates at 90 days were 25% and 41%, respectively. In the subgroup with appendicolith, as compared with those who had surgery, those who received antibiotics had more percutaneous drainage procedures (6 more per every 100 patients), but surgeries more extensive than appendectomy (e.g., ileocecectomy) were rare and occurred with similar frequency in those undergoing appendectomy. In two trials reporting follow-up for 5 years, 30 to 40% of the patients who received treatment with antibiotics ultimately underwent appendectomy, usually within 1 to 2 years. 

Q: What are some of the antibiotics used for the nonoperative treatment of acute uncomplicated appendicitis?

A: A parenteral antibiotic regimen that is active against aerobic Gram-negative and anaerobic bacteria and consistent with community-acquired intraabdominal infection guidelines should be initiated as soon as the diagnosis of appendicitis has been reasonably established, regardless of whether treatment will be operative or nonoperative. If nonoperative treatment is anticipated, then the administration of a long-acting parenteral antibiotic, such as ertapenem or ceftriaxone, along with high-dose, once-daily metronidazole, can facilitate early discharge (including, in some cases, after one dose in the emergency department), especially if there is concern regarding recurrent nausea or initial adverse reactions to oral medications. Parenteral antibiotics are followed by oral regimens, such as metronidazole, administered with an advanced-generation cephalosporin or fluoroquinolone, for a total of 7 to 10 days. Although ampicillin–sulbactam and amoxicillin–clavulanate have been used effectively in some trials, current guidelines recommend against their use because of high rates of Escherichia coli resistance to these antibiotics.

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