Appendicitis
Exam Tips
- Classic sequence for OSCE viva: migratory pain (central to RIF) plus anorexia and focal peritonism strongly suggests appendicitis.
- Always state key exclusions in reproductive-age patients: pregnancy test and gynaecological causes before anchoring on appendicitis.
- Atypical groups are high risk: children, older adults, and pregnancy can present with subtle or displaced signs; maintain low threshold for imaging/senior review.
- Mention complication clues that change urgency: sudden pain relief then sepsis, generalized guarding, palpable mass, persistent tachycardia, or hypotension.
- In management stations, gain marks by combining: NBM, IV fluids, broad-spectrum IV antibiotics, analgesia, and urgent surgical referral.
- See Figure: surface anatomy of McBurney's point and appendix positional variants in your core surgical anatomy text when revising examination signs.
Definition
Acute appendicitis is an acute inflammatory syndrome of the vermiform appendix, usually presenting with evolving abdominal pain and systemic upset over hours to 1-2 days. It is a time-critical surgical diagnosis because progression from simple inflammation to ischaemia, gangrene, and perforation can occur rapidly, although a proportion of uncomplicated cases may settle with non-operative treatment.
Pathophysiology
In around half of cases, obstruction of the appendiceal lumen (for example by faecolith, lymphoid hyperplasia, impacted stool, or rarely tumour) triggers mucus accumulation, bacterial overgrowth, and rising intraluminal pressure. Venous and lymphatic outflow are then compromised, leading to mural oedema, arterial ischaemia, and necrosis; this may progress to perforation, abscess, or generalized peritonitis. Common organisms are mixed aerobic/anaerobic gut flora (notably Escherichia coli and Bacteroides species). Anatomical variation of appendix position (retrocaecal, pelvic, pre-/post-ileal) explains atypical pain patterns and examination findings.
Risk Factors
- Age 10-30 years (peak in adolescence), though can occur at any age
- Male sex (slightly higher incidence)
- Positive family history (approximately three-fold increased risk)
- Smoking and passive smoke exposure
- Frequent prior antibiotic exposure (microbiome disturbance hypothesis)
- Lower socioeconomic status
- Possible seasonal variation (higher rates in summer)
- Pregnancy (most common non-obstetric surgical emergency in pregnancy)
Clinical Features
Symptoms
- Central/periumbilical or epigastric pain migrating to the right iliac fossa over 24-48 hours
- Pain worsened by movement, coughing, or bumps while travelling
- Anorexia, nausea, and sometimes vomiting
- Low-grade fever and malaise
- Constipation or diarrhoea
- Sudden pain relief followed by clinical deterioration may indicate perforation
- Atypical patterns: right loin pain (retrocaecal appendix), diarrhoea/vomiting with ileal irritation, right upper quadrant/flank pain in later pregnancy
Signs
- Right lower quadrant tenderness, classically maximal at McBurney's point
- Localized guarding, rebound/percussion tenderness
- Rovsing's, psoas, or obturator signs may be positive
- Tachycardia and low-grade pyrexia (<38 C) are common early findings
- Reduced/absent bowel sounds may suggest ileus or peritonitis
- Palpable right iliac fossa mass suggests appendiceal phlegmon/abscess
- Children may have pain on hopping/coughing; older adults may have muted abdominal signs despite severe disease
Investigations
Management
Lifestyle Modifications
- Urgent same-day surgical assessment; do not delay for repeated outpatient review
- Nil by mouth once appendicitis is suspected and surgery is possible
- IV fluid resuscitation and early sepsis recognition/escalation
- Smoking cessation advice during recovery to reduce postoperative complications
Pharmacological Treatment
Analgesia
- Paracetamol 1 g orally or IV every 4-6 hours (maximum 4 g/day)
- Morphine sulfate 2.5-10 mg IV titrated in small boluses for severe pain
Provide adequate analgesia early; pain relief does not mask important signs when reassessment is structured. Reduce opioid doses in frailty/renal impairment and monitor for respiratory depression, hypotension, and nausea.
Antiemetic
- Ondansetron 4 mg IV/IM every 8-12 hours as needed
- Cyclizine 50 mg IV/IM up to every 8 hours as needed
Check QT-risk factors with ondansetron (electrolyte disturbance, interacting QT-prolonging drugs). Cyclizine may cause drowsiness and anticholinergic effects.
Empiric antibiotics (pre-operative and/or non-operative selected uncomplicated cases)
- Co-amoxiclav 1.2 g IV every 8 hours
- If penicillin allergy: cefuroxime 1.5 g IV every 8 hours plus metronidazole 500 mg IV every 8 hours (if cephalosporin appropriate)
- If severe beta-lactam allergy: ciprofloxacin 400 mg IV every 12 hours plus metronidazole 500 mg IV every 8 hours
Choose regimen per local antimicrobial policy and severity. Send cultures in sepsis/perforation and de-escalate to sensitivities. Important safety points: avoid co-amoxiclav in true immediate penicillin anaphylaxis; use caution with fluoroquinolones (tendinopathy, aortic risk, CNS effects, QT prolongation), and avoid in pregnancy unless specialist advice.
Venous thromboembolism prophylaxis (perioperative risk-based)
- Enoxaparin 40 mg subcutaneously once daily (prophylactic dose in adults with normal renal function)
Adjust dose in renal impairment and low body weight; contraindicated in active bleeding or severe thrombocytopenia.
Surgical / Interventional
- Laparoscopic appendicectomy is standard definitive treatment for most operable cases
- Open appendicectomy if laparoscopy contraindicated or technically unsuitable
- Complicated appendicitis (perforation/abscess/peritonitis): source control with appendicectomy ± washout; image-guided drainage for selected localized abscesses
- Selected uncomplicated appendicitis may be managed initially with antibiotics and close review, acknowledging recurrence risk and need for later surgery
- In pregnancy, urgent multidisciplinary surgical and obstetric input; avoid diagnostic and operative delay
Complications
- Perforation (often within 24 hours in some cases)
- Appendiceal abscess or inflammatory phlegmon (appendix mass)
- Generalized peritonitis
- Sepsis and septic shock
- Postoperative wound infection or intra-abdominal collection
- Adhesive small bowel obstruction
- Stump appendicitis after prior appendicectomy
- Adverse pregnancy outcomes (fetal loss, preterm delivery), especially with perforation
- Incidental appendiceal neoplasm in resected specimens (rare)
Prognosis
Outcome is usually excellent with early diagnosis and timely source control. Morbidity and mortality rise substantially with perforation, delayed treatment, advanced age, and multimorbidity; older adults have higher rates of complicated disease and death than younger patients. Non-operative treatment of uncomplicated disease can be successful in selected patients, but recurrence is clinically important (around one-quarter in observational cohorts), so follow-up and safety-netting are essential.
Sources & References
🏥BMJ Best Practice(2)
✅NICE Guidelines(1)
- Appendicitis[overview]
📖Textbook References(5)
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 613)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 635, 636)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 637, 638)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 643)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 637, 638)[context]