Acute Appendicitis

Acute appendicitis is the commonest surgical emergency; diagnosis is clinical, supported by the Alvarado score. USS is first-line imaging in women and children; CT abdomen/pelvis is the gold standard in adults. Definitive treatment is laparoscopic…

Alvarado Score / NICE NG121

The pathway

1 · Alvarado scoring

Migration of pain to RIF: 1 point
Anorexia: 1 point
Nausea/vomiting: 1 point
RIF tenderness: 2 points
Rebound tenderness: 1 point
Elevated temperature (>37.3°C): 1 point
Leukocytosis (WBC >10): 2 points
Score ≥7: high probability, arrange surgical review; 4–6: equivocal, imaging; <4: low probability

2 · Clinical signs

Rovsing's sign: RIF pain on palpation of LIF (peritoneal irritation)
Psoas sign: pain on hip extension (retrocaecal appendix)
Obturator sign: pain on internal rotation of flexed hip (pelvic appendix)
Hartmann's point: maximal tenderness at junction of middle and outer thirds of line from umbilicus to ASIS

3 · Mandatory investigations

FBC: WBC >10 × 10⁹/L supports diagnosis
CRP: elevated (>80 suggests established inflammation)
βhCG: mandatory in all women of reproductive age to exclude ectopic pregnancy
Urine dip + MSU: exclude UTI as mimic

4 · Imaging

USS: first-line in women and children (avoids radiation; sensitivity ~75%, specificity ~95%)
CT abdomen/pelvis (with contrast): gold standard in adults — sensitivity >95%, specificity >95%
MRI: preferred in pregnancy

5 · Surgical referral criteria

Alvarado ≥7: refer surgical team immediately
Peritonism on examination: emergency surgical referral regardless of score
Perforation/abscess on imaging: urgent surgical or interventional radiology

6 · Antibiotic prophylaxis

Co-amoxiclav 1.2g IV at induction (single dose for uncomplicated)
Metronidazole 500mg IV if penicillin allergy (with cefuroxime or gentamicin)
Perforated appendicitis: therapeutic antibiotics 48–72h post-op

7 · Laparoscopic vs open

Laparoscopic appendicectomy: preferred — faster recovery, lower wound infection rate, diagnostic benefit in women
Open appendicectomy: if laparoscopy unavailable, perforation with widespread contamination, or haemodynamic instability

8 · Post-operative care

Drain in situ if perforation/abscess
Continue antibiotics if perforated (IV until apyrexial, then PO to complete 5–7 days)
Histology: exclude carcinoid or other pathology
Early mobilisation and discharge (laparoscopic: 24–48h)

Drugs

Drug	Dose	Route	Notes
Co-amoxiclav	1.2g	IV	Single prophylactic dose at induction. Extend therapeutically if perforated.
Metronidazole	500mg	IV	If penicillin allergy — combine with cefuroxime or gentamicin.
Morphine	5–10mg	IV	Titrate to pain. Analgesia does NOT mask signs — do not withhold.
Ondansetron	4mg	IV	Antiemetic. Administer with opioids.
Paracetamol	1g	IV	Regular analgesia, Q6h. Safe in all patients including pregnancy.

When to escalate

Alvarado score ≥7 — immediate surgical referral,Peritonism or clinical perforation — emergency laparotomy,Haemodynamic instability — resuscitate and emergency theatre,Pregnancy with suspected appendicitis — obstetric + surgical co-management, MRI preferred,Paediatric patient — lower threshold for CT (consider USS first to avoid radiation)

Reference: NICE NG121 2021 / Association of Surgeons of Great Britain and Ireland (ASGBI) Guidelines

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