What is the appropriate workup and treatment for an appendiceal (appendix) mass?

From the Guidelines

The management of an appendiceal mass typically involves initial conservative treatment with antibiotics rather than immediate surgery. When a patient presents with an appendiceal mass, start with broad-spectrum antibiotics such as piperacillin-tazobactam 3.375g IV every 6 hours or a combination of ceftriaxone 1-2g IV daily plus metronidazole 500mg IV every 8 hours for 5-7 days, as recommended by the World Society of Emergency Surgery guidelines 1. This should be accompanied by bowel rest, IV fluids, and close monitoring.

Key Considerations

• If the patient improves clinically (decreased pain, fever resolution, and normalization of inflammatory markers), they can be discharged on oral antibiotics such as amoxicillin-clavulanate 875/125mg twice daily or ciprofloxacin 500mg twice daily plus metronidazole 500mg three times daily to complete a 7-10 day course.
• After resolution of the acute inflammation, an interval appendectomy is typically recommended 6-8 weeks later to prevent recurrence and to rule out underlying malignancy, particularly in older patients, as suggested by the guidelines 1.
• If the patient fails to improve with conservative management or develops signs of peritonitis, sepsis, or abscess formation, immediate surgical intervention is necessary.
• For abscesses, CT-guided percutaneous drainage may be performed before surgery, as supported by the American College of Radiology Appropriateness Criteria 1.

Rationale

This conservative-first approach is preferred because immediate surgery on an appendiceal mass carries higher risks of complications including bowel injury, excessive bleeding, and incomplete appendectomy. The use of broad-spectrum antibiotics and percutaneous drainage, when necessary, can help reduce these risks and improve patient outcomes, as indicated by the guidelines 1 and supported by the American College of Radiology Appropriateness Criteria 1.

From the FDA Drug Label

1. 2 Complicated Intra-abdominal Infections (Adult and Pediatric Patients) Meropenem for injection is indicated for the treatment of complicated appendicitis and peritonitis caused by viridans group streptococci, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacteroides fragilis, B. thetaiotaomicron,and Peptostreptococcusspecies.

The treatment of an appendiceal mass may involve the use of meropenem as part of the management of complicated intra-abdominal infections, including complicated appendicitis.

• The recommended dose for intra-abdominal infections is 1 gram given every 8 hours.
• Meropenem should be administered by intravenous infusion over approximately 15 minutes to 30 minutes.
• The decision to use meropenem should be based on the suspected or proven causative bacteria and the patient's renal function, among other factors 2.

From the Research

Workup of Appendiceal Mass

• The diagnosis of appendiceal mass is based on clinical presentation, laboratory evaluation, and imaging studies, such as ultrasound or computerized tomography (CT) scan 3, 4.
• CT findings, such as appendiceal dilatation, presence of appendicoliths, mass effect, and a dilated appendix greater than 13 mm, can help identify patients who are at higher risk of treatment failure with an antibiotics-first approach 5.

Treatment of Appendiceal Mass

• Conservative management with antibiotics is a highly acceptable approach for appendiceal mass, especially in patients without high-risk CT findings 5, 3, 4.
• Interval appendicectomy may be considered after conservative management, especially in patients with persistent right iliac fossa pain 3, 4.
• Emergency appendicectomy is emerging as an alternative to conventional conservative treatment, and is feasible, safe, and cost-effective 6.
• Laparoscopic appendicectomy, whether in emergency or interval settings, is feasible and safe, and should replace the conventional open method 4, 6.
• The decision to perform surgery should be based on individual patient factors, such as the presence of high-risk CT findings, patient preferences, and perioperative risk assessment 5, 6.

Management Strategies

• Patients with appendiceal mass can be divided into three groups: emergency operation, delayed operation, and follow-up group 7.
• Patients who undergo conservative management can be followed up without surgery, and appendicectomy can be considered if there are recurrent symptoms 7, 6.
• In patients over 40 years of age, other pathological causes of right iliac mass must be excluded by further investigations, and a close follow-up is needed 6.