Acute abdomen and emergencies
Right iliac fossa pain and appendicitis
Overview and approach
Right iliac fossa pain includes appendicitis and gastrointestinal, urinary and gynaecological emergencies.
- Appendicitis is the commonest surgical emergency of the abdomen; diagnosis combines clinical scoring, labs and selective imaging (1).
- Approach: stratify risk (score), image the intermediate-risk group, then operate or treat with antibiotics (1).
Assessment and clinical features
Assess pain migration, vomiting, bowel/urinary symptoms, fever, last menstrual period and pregnancy possibility; examine for peritonism.
- Classic: periumbilical pain migrating to the RIF, anorexia, nausea, low-grade fever, RIF tenderness (McBurney point), guarding, rebound; Rovsing, psoas and obturator signs are supportive. Presentation is atypical in children, older adults, pregnancy and retrocaecal appendix.
- Alvarado score (migration, anorexia, nausea/vomiting, RIF tenderness, rebound, fever, leucocytosis, left shift): a score under 5 is highly sensitive for excluding appendicitis but should not be used to confirm it (1).
Differentials and investigations
FBC/CRP, urine and pregnancy testing where relevant; ultrasound or CT selected for patient/context. Consider ectopic pregnancy, torsion, Crohn’s and ureteric stone.
- Differentials: mesenteric adenitis, terminal ileitis/Crohn’s, caecal diverticulitis, right ureteric colic, ovarian torsion/cyst, ectopic pregnancy, PID, testicular torsion, UTI.
- Bloods/urine: FBC, CRP, urinalysis, beta-hCG in women of reproductive age.
- Imaging for intermediate-risk patients: ultrasound/POCUS first; if non-diagnostic, CT (low-dose, contrast-enhanced preferred) or repeat ultrasound; MRI is preferred in pregnancy (1).
Management and follow-up
Analgesia, hydration, surgical review and management directed by diagnosis; do not withhold analgesia to preserve signs.
- Analgesia, IV fluids, nil by mouth, early surgical review. Antibiotics per eTG/local guideline.
- Laparoscopic appendicectomy is the preferred operation. For selected uncomplicated appendicitis without an appendicolith, antibiotics-first treatment can be discussed (IV then oral antibiotics), with recurrence up to about 39% at five years (1).
- Complicated appendicitis (perforation, abscess, phlegmon) needs resuscitation, antibiotics and surgical or percutaneous source control.
Red flags and clinical pearls
Peritonitis, shock, pregnancy with concerning pain/bleeding or a deteriorating child needs urgent escalation.
- Always check pregnancy status; ectopic pregnancy and torsion mimic appendicitis.
- Generalised peritonitis or sepsis suggests perforation: resuscitate and expedite theatre.
- A normal CRP/WCC does not exclude early appendicitis; re-examine serially.
- Viva: Alvarado score, role of imaging, antibiotics-first option and its recurrence rate.
Last updated from Sen’s notes on 9 October 2026.