Synopsis
Diagnose appendicitis across typical and atypical presentations, identify perforation or sepsis early, and coordinate imaging, antibiotics and surgical source control safely.
- Classic appendicitis begins with poorly localised central abdominal pain that migrates to the right iliac fossa as parietal peritoneum becomes inflamed.
- Anorexia, nausea, low-grade fever and focal guarding support the diagnosis, but their absence does not exclude appendicitis in older adults, pregnancy or immunosuppression.
- Retrocaecal inflammation may cause flank or back pain with little anterior guarding; a pelvic appendix may produce suprapubic pain, diarrhoea or urinary symptoms.
- Check pregnancy status in anyone with reproductive potential because ectopic pregnancy changes both urgency and the safest imaging pathway.
- Ultrasound is preferred first in many children and pregnant patients; CT is usually the most accurate test for non-pregnant adults with diagnostic uncertainty.
- Risk scores organise probability but cannot replace repeated examination, imaging and senior review when the clinical course is discordant.
- Appendicectomy remains usual definitive treatment; antibiotics alone may be discussed for carefully selected imaging-confirmed uncomplicated disease with explicit recurrence and failure counselling.
- An appendiceal mass or abscess may need antibiotics, image-guided drainage and delayed evaluation rather than hazardous immediate dissection; the colorectal cause must be considered in older patients.
Key red flags
Pain migrates from periumbilical or epigastric discomfort to the right iliac fossa, with anorexia, nausea and focal tenderness near McBurney's point; movement, coughing or percussion may worsen pain.
High fever, tachycardia, marked guarding, rebound, a palpable mass, prolonged symptoms or systemic toxicity suggest gangrene, perforation, phlegmon or abscess and require urgent surgical planning.
Anatomical displacement and physiological leucocytosis can blur classic signs. Maintain early obstetric and surgical involvement and use pregnancy-adapted ultrasound or MRI pathways rather than delaying assessment.
Pain, fever and leukocytosis can be muted despite perforation. Lower the threshold for CT and senior review, and consider caecal cancer or another structural lesion.
Haemodynamic compromise, vaginal bleeding, sudden unilateral pelvic pain, pain out of proportion, pulsatile mass or testicular pain should redirect immediately toward ectopic pregnancy, torsion, ischaemia, aneurysm or torsion.
Investigation priorities
Track localisation, peritonism and physiological deterioration over time.
Management branches
Localised right iliac fossa pain without shock or generalised peritonitis.
- Assess ABCDE, provide analgesia and antiemetic treatment, establish venous access, check hydration and keep the patient nil by mouth pending a surgical decision.
- Obtain blood tests, urinalysis and a pregnancy test where relevant; involve the acute surgical team and document serial examinations rather than relying on one score.
- Select ultrasound, CT or MRI using age, pregnancy status, probability and local expertise; if imaging remains equivocal, agree observation and reassessment intervals explicitly.
- When confirmed, discuss laparoscopic appendicectomy and perioperative antibiotics; antibiotics-first care is restricted to selected uncomplicated cases with informed consent and reliable follow-up.