Appendicitis: Alvarado Score, Imaging, and Appendectomy
Appendicitis is the most common abdominal surgical emergency. Peak incidence is 10–30 years of age. Lifetime risk is ~7%. Missing it leads to perforation (30% rate) with peritonitis and sepsis; overtreating it leads to unnecessary surgery. Risk stratification and appropriate imaging prevent both errors.
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Progress Note Editorial · Evidence-based
Updated July 2026
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Classic progression: periumbilical colicky pain → migration to RLQ (McBurney's point — 1/3 of the way from ASIS to umbilicus) → nausea/vomiting → fever → RLQ tenderness + guarding. Rebound tenderness and Rovsing sign (LLQ pressure → RLQ pain) support peritoneal irritation. Psoas sign: RLQ pain with right hip extension (retrocecal appendix). Obturator sign: RLQ pain with internal rotation of flexed right hip (pelvic appendix). Alvarado (MANTRELS) score: Migration of pain to RLQ (1), Anorexia (1), Nausea/vomiting (1), Tenderness at McBurney's (2), Rebound tenderness (1), Elevated temperature (1), Leukocytosis (2) = max 10. Score ≤4: low risk (likely not appendicitis); 5–6: equivocal (imaging); 7–10: high risk (likely appendicitis, consider direct to OR in classic presentation).
Imaging
CT abdomen/pelvis with IV contrast: gold standard — sensitivity 98%, specificity 98%. Findings: appendix diameter >6mm, periappendiceal fat stranding, appendicolith (calcified fecalith — 20% of cases but high specificity), non-opacification of appendiceal lumen. Ultrasound: preferred in children and pregnant women (no radiation). Sensitivity 75–90% (operator-dependent), specificity 90%. Findings: non-compressible tubular structure >6mm. MRI: best in pregnancy when ultrasound is equivocal — no radiation, good sensitivity for perforation. Plain films: largely unhelpful — appendicolith on KUB is only classic finding. Algorithm: Children and pregnant women → ultrasound first. Adults with classic presentation (Alvarado ≥7) → CT or direct to OR. Adults with equivocal presentation → CT.
Management
Uncomplicated appendicitis: laparoscopic appendectomy (gold standard — faster recovery, lower wound infection than open). Non-operative management (IV antibiotics alone) is effective in ~70% of uncomplicated cases without appendicolith, but recurrence rate ~30% at 5 years — shared decision-making with patient. Antibiotics: ceftriaxone + metronidazole OR piperacillin-tazobactam for 24–48h pre-op. Complicated (perforated/gangrenous) appendicitis: if hemodynamically stable with formed abscess → CT-guided drainage + antibiotics, then interval appendectomy 6–8 weeks later. If peritonitis or hemodynamically unstable → urgent open or laparoscopic appendectomy + washout. Broad-spectrum antibiotics post-operatively for 4–5 days.
Test yourself
Quick check — 3 questions
1. A 19-year-old presents with 18 hours of periumbilical pain that migrated to the RLQ, anorexia, nausea, temp 38.2°C, and WBC 14,500. His Alvarado score is 8. CT shows an appendix 9mm in diameter with periappendiceal fat stranding. The next step is:
Explanation. Alvarado score 8 + classic clinical features + CT confirming uncomplicated appendicitis → laparoscopic appendectomy. Non-operative management (antibiotics alone) is an option for uncomplicated appendicitis in selected patients but requires shared decision-making. This patient has a classic presentation with CT confirmation — surgery is the standard of care and most reliable treatment.
2. RLQ pain worsened by internal rotation of the flexed right hip (obturator sign) suggests the appendix is located:
Explanation. The obturator sign tests for irritation of the obturator internus muscle. A pelvic (low-lying) appendix positioned near the obturator internus will be irritated by rotation of the hip. The psoas sign (pain with right hip extension) suggests a retrocecal appendix lying on the right psoas major. Knowing the anatomical position explains atypical presentations.
3. A 45-year-old woman has a 5-day history of RLQ pain that has improved. CT shows a pericecal abscess 5cm, no free air or peritonitis. The optimal management is:
Explanation. Perforated appendicitis with a contained abscess (not free peritonitis) is managed with CT-guided drainage + IV antibiotics in the acute phase. Immediate surgery has higher complication rates. After resolution of the abscess (4–6 weeks), interval appendectomy is performed to prevent recurrence (~15–20% recurrence without surgery) and to exclude malignancy as the underlying cause.
Frequently asked questions
Why does appendicitis pain migrate from periumbilical to RLQ?
Early appendicitis causes visceral pain (from distension of the appendix) transmitted via T8–T10 visceral afferents — perceived as dull, colicky, periumbilical pain (visceral pain is poorly localized and referred to the periumbilical region for mid-gut structures). As inflammation progresses to involve the parietal peritoneum overlying the appendix (which is richly innervated by somatic sensory nerves), pain becomes sharp, well-localized, and constant at McBurney's point in the RLQ. This migration of pain is the classic diagnostic clue.
Is CT scan safe in children with suspected appendicitis?
The increased radiation exposure from CT raises theoretical lifetime cancer risk in children — cumulative pediatric CT exposure is a real concern. Current practice: start with graded-compression ultrasound in children. If ultrasound is diagnostic (appendix >6mm, non-compressible) → proceed. If ultrasound is non-diagnostic → MRI (preferred over CT in many children's hospitals) or CT if MRI unavailable/delayed. CT reserved for cases where ultrasound/MRI unavailable or equivocal and clinical urgency requires definitive imaging. Shared decision between surgeon, radiologist, and family.
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