Last reviewed: March 2026
Contents
MDM Templates
Uncomplicated Appendicitis
Patient presents with right lower quadrant abdominal pain. Imaging confirms acute uncomplicated appendicitis without evidence of perforation, abscess, or appendicolith. Well appearing without peritoneal signs on exam.
History, exam, and imaging not consistent with other dangerous causes of RLQ pain including ovarian torsion, ectopic pregnancy, strangulated hernia, or mesenteric ischemia.
Plan: Antibiotics initiated — cefoxitin 2 g IV. Antiemetic and analgesia. Surgery consulted regarding operative versus nonoperative management.
Disposition: Admit to surgery.
Complicated / Perforated Appendicitis
Patient presents with RLQ pain and imaging demonstrates complicated appendicitis with evidence of ***. Peritoneal signs present on exam. Hemodynamically stable.
Plan: Broad-spectrum antibiotics initiated — piperacillin-tazobactam 3.375 g IV. IV fluid resuscitation. Surgery consulted emergently for operative management.
Disposition: Admit to surgery.
If phlegmon or contained abscess without free perforation:
Imaging demonstrates periappendiceal phlegmon/abscess without free perforation. Surgery consulted — plan for IV antibiotics and interval appendectomy versus percutaneous drainage per surgical preference.
Antibiotics-Only Management (CODA Protocol)
Patient with imaging-confirmed uncomplicated appendicitis. No appendicolith, no abscess, no perforation. After shared decision-making, patient elects trial of antibiotics-only management per CODA protocol. Risks including ~30% crossover to appendectomy within 90 days discussed.
Plan: Ceftriaxone 2 g IV + metronidazole 500 mg IV in ED. Discharge antibiotics: ciprofloxacin 500 mg PO BID + metronidazole 500 mg PO TID for 10 days. Patient counseled regarding disulfiram-like reaction with metronidazole and alcohol.
Disposition: Discharge with strict return precautions for worsening pain, fever, inability to tolerate PO, or new peritoneal signs. Follow up with surgery within 24–48 hours.
Clinical Education
Diagnosis Pearls
The classic migration pattern (periumbilical to RLQ) is present in only ~50–60% of cases. Appendicitis should remain on the differential for any patient with acute abdominal pain, even with atypical location. Retrocecal appendicitis may present with flank or back pain; pelvic appendicitis may mimic UTI or gynecologic pathology.[1]
No single exam finding rules in or rules out appendicitis. McBurney point tenderness, Rovsing sign, psoas sign, and obturator sign all have modest sensitivity and specificity individually. The overall clinical gestalt — combining history, exam, and labs — is more useful than any single finding.[2]
WBC and CRP are helpful but imperfect. A normal WBC does not rule out appendicitis (sensitivity ~80%). CRP adds incremental value, especially when combined with WBC — both being normal makes appendicitis unlikely. An elevated CRP > 1 mg/dL in combination with leukocytosis increases the post-test probability significantly.[3]
Alvarado and AIR Scores
The Alvarado Score is useful for risk stratification. Score ≤3 has a high negative predictive value and may help identify patients who can be safely observed or discharged. Score ≥7 is highly suggestive and can guide the decision to proceed directly to imaging or surgical consult.[4]
The Appendicitis Inflammatory Response (AIR) Score outperforms Alvarado in validation studies. It incorporates CRP (which Alvarado does not) and better discriminates between low, intermediate, and high probability groups. Low AIR score (0–4) has a negative appendicitis rate of ~2%.[5]
Imaging Approach
CT abdomen/pelvis with IV contrast is the standard in adults — sensitivity 94–98%, specificity 95–98%. Oral contrast adds time and rarely changes management; most institutions have moved away from routine oral contrast for appendicitis evaluation.[6]
Ultrasound first in pregnant patients and pediatrics. If US is nondiagnostic, MRI is the next step in pregnancy. In pediatrics, if US is equivocal and clinical suspicion remains high, CT with IV contrast is appropriate — do not let radiation avoidance delay diagnosis of a surgical emergency.[7]
An appendicolith on imaging matters for management. The CODA trial showed that patients with an appendicolith had significantly higher rates of treatment failure with antibiotics-only management (~40% vs ~25% without appendicolith). Most surgeons consider appendicolith a relative contraindication to nonoperative management.[8]
Antibiotic Selection
| Scenario | IV Regimen | PO Transition |
| Uncomplicated (pre-op) | Cefoxitin 2 g IV | N/A (single pre-op dose) |
| CODA protocol (abx only) | Ceftriaxone 2 g + metronidazole 500 mg IV | Cipro 500 mg BID + metronidazole 500 mg TID x 10 days |
| Complicated / perforated | Piperacillin-tazobactam 3.375 g IV q6h | Per surgery (typically 4–7 days total) |
The CODA Trial
The CODA trial (2020) demonstrated that antibiotics alone are a reasonable alternative to surgery for uncomplicated appendicitis. At 90 days, ~71% of patients randomized to antibiotics avoided surgery. However, ~30% crossed over to appendectomy — mostly within the first 90 days — and complication rates were slightly higher in the antibiotics group (including 8% with appendicolith who developed perforation).[8]
The key exclusion for CODA: appendicolith. Patients with appendicoliths had significantly worse outcomes with antibiotics-only management. Most experts consider appendicolith a relative contraindication to nonoperative management.
Shared decision-making is essential. The antibiotics-only approach is not “better” — it is an alternative with different tradeoffs. Surgery is definitive (~97% cure rate). Antibiotics avoid an operation but carry a ~30% recurrence/crossover rate. Patients need to understand both options.
Special Populations
Pregnancy: Appendicitis is the most common non-obstetric surgical emergency in pregnancy. The appendix migrates superiorly as the uterus enlarges — pain may localize to the right upper quadrant in the third trimester. US first, then MRI if equivocal. Delayed diagnosis increases perforation risk, which is associated with fetal loss. Surgery should not be delayed for imaging if clinical suspicion is high.[7]
Elderly: Appendicitis in patients over 65 carries higher morbidity and mortality because of atypical presentations, delayed diagnosis, and higher perforation rates (up to 50% at presentation). Maintain a low threshold for imaging. WBC may be less reliable in this population.[1]
Pediatrics: Children under 5 have perforation rates >80% because they present late and are harder to examine. Ultrasound is first-line imaging. An experienced pediatric surgical team should be involved early.
Disposition
Uncomplicated appendicitis going to OR: Admit to surgery. Laparoscopic appendectomy is standard of care.
CODA protocol discharge criteria: Uncomplicated imaging (no appendicolith, no perforation, no abscess), tolerating PO, pain controlled, reliable follow-up within 24–48 hours, understands return precautions.
Admit if: Complicated appendicitis (perforation, abscess, phlegmon), inability to tolerate PO, uncontrolled pain, unreliable follow-up, or hemodynamic instability.
References
- Snyder MJ et al. Acute appendicitis: efficient diagnosis and management. Am Fam Physician. 2018;98(1):25-33. PubMed
- Wagner JM et al. Does this patient have appendicitis? JAMA. 1996;276(19):1589-1594. PubMed
- Andersson RE. Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Br J Surg. 2004;91(1):28-37. PubMed
- Ohle R et al. The Alvarado score for predicting acute appendicitis: a systematic review. BMC Med. 2011;9:139. PubMed
- Andersson M, Andersson RE. The appendicitis inflammatory response score: a tool for the diagnosis of acute appendicitis that outperforms the Alvarado score. World J Surg. 2008;32(8):1843-1849. PubMed
- Bixby SD et al. Imaging in the evaluation of appendicitis. Radiol Clin North Am. 2019;57(3):463-481. PubMed
- ACOG Committee Opinion No. 775. Nonobstetric surgery during pregnancy. Obstet Gynecol. 2019;133(4):e285-e286. PubMed
- CODA Collaborative. A randomized trial comparing antibiotics with appendectomy for appendicitis. N Engl J Med. 2020;383(20):1907-1919. PubMed
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