Acute Appendicitis Clinical Overview
I. The "On-Call" Snapshot
Clinical Significance in Malaysia: This is the most common cause of a non-traumatic acute abdomen presenting to any Emergency Department in Malaysia. You will see this on every call.
High-Yield Definition: Acute appendicitis is the inflammation of the inner lining of the vermiform appendix that spreads to its other parts. (Source: StatPearls, 2023).
Clinical One-Liner: Basically, it’s an inflamed, angry appendix, usually in a young person whose periumbilical pain has now shifted to the right iliac fossa (RIF) and they've gone off their food.
II. Etiology & Risk Factors
Etiology: The primary cause is luminal obstruction.
In adults: Most commonly due to a faecolith (a hard mass of stool).
In children: Often due to lymphoid hyperplasia, usually following a recent viral illness.
Risk Factors:
Non-Modifiable: Age (peak incidence 10-30 years), Male sex.
Modifiable: Low-fibre diet is a classically taught risk factor, though the evidence is not very strong.
III. Quick Pathophysiology
This is simple and you need to understand it.
Obstruction: The appendix lumen gets blocked.
Stasis & Distension: Mucus secretion continues, bacteria multiply (like E. coli, Bacteroides), and the appendix swells like a balloon. This stimulates visceral nerves, causing a vague, central periumbilical pain.
Ischemia: The swelling compromises blood supply.
Inflammation & Translocation: The inflammation spreads to the outer wall and irritates the adjacent parietal peritoneum. This is when the pain becomes sharp, constant, and localised to the RIF.
Perforation/Gangrene: If untreated, the ischaemic wall dies and ruptures, leading to peritonitis or an abscess.
IV. Clinical Assessment
Red Flags & Immediate Actions: If you see these, you escalate to your senior immediately.
Tachycardia (HR > 100) and Hypotension (SBP < 90 mmHg): -> Alert senior, secure TWO large-bore IV branulas, start fluid resuscitation (e.g., 500ml Hartmann's STAT), and take urgent bloods including GXM. This could be sepsis from perforation.
High-grade Fever (> 38.5°C): -> Suspect perforation or abscess. Administer IV paracetamol, get blood cultures, and start antibiotics after discussing with your senior.
Generalised Abdominal Guarding / Rigidity: -> This is peritonitis. The patient needs urgent surgical review. Keep them strictly Nil by Mouth (NBM).
History:
Common (>50%):
Migratory abdominal pain (starts periumbilical, moves to RIF over 12-24 hours). This is the most specific symptom.
Anorexia (loss of appetite). The "hamburger sign" - if a patient is hungry enough to eat their favourite food, it's less likely to be appendicitis.
Nausea.
Less Common (10-50%): Vomiting (usually follows the pain), low-grade fever.
Pertinent Negatives: Actively ask to rule out differentials.
"Any urinary symptoms like pain on urination or frequency?" (Rules out UTI).
For females: "What is the first day of your last menstrual period (LMP)? Any chance of pregnancy? Any vaginal bleeding or discharge?" (Rules out ectopic pregnancy, PID).
Physical Examination:
General: Patient lies still, as movement hurts. Low-grade fever is typical.
Abdomen:
Look: No obvious signs usually, maybe reduced abdominal movement on respiration.
Feel:
Maximum tenderness at McBurney's point (two-thirds of the way from the umbilicus to the anterior superior iliac spine).
Rebound tenderness and guarding in the RIF suggest peritoneal irritation.
Rovsing's sign: Palpation of the left iliac fossa causes pain in the right.
Psoas sign: Pain on passive extension of the right hip (suggests a retrocaecal appendix).
Obturator sign: Pain on internal rotation of the flexed right hip (suggests a pelvic appendix).
Clinical Pearl: In the elderly, pain and inflammatory markers can be deceptively mild. They may present with confusion or just non-specific abdominal pain. Have a much lower threshold for imaging in this group.
V. Diagnostic Workflow
Your primary role is not to be 100% certain, but to have a high index of suspicion and rule out the "can't miss" differentials. The Alvarado Score is a useful tool to stratify risk.
Differential Diagnosis:
Ectopic Pregnancy (in females):
Points For: Lower abdominal pain, may have amenorrhoea.
Points Against: Pain is usually sudden, may have vaginal bleeding.
How to Differentiate: Urine pregnancy test (UPT) is mandatory for ALL females of childbearing age.
Ureteric Colic:
Points For: Can present as right-sided abdominal pain.
Points Against: Pain is classically "loin-to-groin", colicky, patient is writhing in pain (unlike the still appendicitis patient).
How to Differentiate: Urine FEME (looking for microscopic haematuria). A non-contrast CT KUB is the gold standard if diagnosis is uncertain.
Mesenteric Adenitis (in children/young adults):
Points For: RIF pain, fever, vomiting.
Points Against: Often has a preceding history of an upper respiratory tract infection. Pain is usually less localised.
How to Differentiate: Very difficult clinically. Ultrasound may show enlarged mesenteric lymph nodes without a clear appendicitis. Often a diagnosis made after observation or imaging.
Investigations Plan:
Bedside / Initial (First 15 Mins):
Urine Pregnancy Test: Must be done and documented for every female aged 12-55.
Urine Dipstick: To look for leukocytes, nitrites (UTI) or blood (renal colic).
First-Line Labs & Imaging:
Full Blood Count (FBC): Expect a neutrophilic leukocytosis (elevated white cell count, mainly neutrophils).
C-Reactive Protein (CRP): Usually elevated (>10 mg/L). A normal FBC and CRP makes appendicitis very unlikely.
Ultrasound Abdomen: This is our first-line imaging modality in most district hospitals, especially for children and females. We look for a non-compressible, blind-ending tubular structure >6mm in diameter in the RIF.
Confirmatory / Gold Standard:
CT Abdomen & Pelvis with IV contrast: This is the gold standard. It has high sensitivity and specificity and can identify complications like abscesses. We reserve it for cases where the diagnosis is clinically and sonographically equivocal. You must discuss with your senior or the surgical team before ordering this.
VI. Staging & Severity Assessment
We generally classify it simply:
Uncomplicated Appendicitis: The appendix is inflamed but intact.
Complicated Appendicitis: There is evidence of gangrene, perforation, phlegmon (an inflammatory mass), or abscess formation.
This distinction is critical because it determines the urgency of surgery, the duration of antibiotics, and the overall prognosis. Complicated cases require longer post-operative antibiotic courses.
VII. Management Plan
Immediate Stabilisation (The ABCDE Plan in ED):
NBM: Keep the patient Nil by Mouth in anticipation of surgery.
IV Access: Secure a large bore branula (e.g., G18/G20).
IV Fluids: Start maintenance fluids (e.g., Hartmann's solution or Normal Saline). Give a bolus if the patient is hypotensive.
IV Analgesia: Give IV Paracetamol 1g. Avoid strong opioids until a surgical plan is made as they can mask clinical signs.
IV Antibiotics: Once the decision to refer to surgery is made, start broad-spectrum antibiotics to cover gram-negatives and anaerobes. A common regimen in Malaysia is IV Cefuroxime 1.5g TDS and IV Metronidazole 500mg TDS.
Definitive Treatment (The Ward Round Plan):
First-Line: Appendicectomy is the definitive treatment.
Laparoscopic appendicectomy is preferred - less pain, faster recovery.
Open appendicectomy is done if laparoscopy is unavailable or contraindicated.
There is a role for non-operative management with antibiotics alone in highly selected cases of uncomplicated appendicitis, but this decision rests solely with the consultant surgeon.
Long-Term & Discharge Plan:
Post-operatively, patients are usually discharged after 1-2 days for uncomplicated cases.
Discharge with oral analgesia and a sick leave certificate (MC).
Advise on wound care and to return if they develop fever, increasing pain, or discharge from the wound.
VIII. Complications
Immediate (first 24 hours):
Perforation: Management: Emergency surgery and IV antibiotics.
Short-Term (days to weeks):
Wound infection: Management: May require drainage and oral antibiotics.
Intra-abdominal Abscess: Management: Usually requires CT-guided percutaneous drainage and prolonged antibiotics.
Long-Term (months to years):
Adhesive Small Bowel Obstruction: Management: Initially conservative (drip and suck), may require surgery if it fails to resolve.
IX. Prognosis
Uncomplicated appendicitis: Mortality is very low (<0.1%). Prognosis is excellent with surgery.
Perforated appendicitis: Mortality increases to ~1-3%, and is significantly higher in the elderly (>10-15%).
Top 3 Prognostic Factors: Age (very young and very old do worse), presence of comorbidities, and time from onset to surgery (delay leads to perforation).
X. How to Present to Your Senior
Be concise and structured.
"Dr., for review please. This is [Patient Name/Age/Gender] in [Location, e.g., Green Zone, Bed 5].
Situation: He presents with a one-day history of migratory abdominal pain, now localised to the right iliac fossa, associated with anorexia and nausea.
Background: He is otherwise healthy with no significant past medical history.
Assessment: On examination, he is tender at McBurney's point with localised guarding. His white cell count is 15 with a high neutrophil count. My main differential is acute appendicitis, with an Alvarado score of 8.
Recommendation: I have kept him NBM, started an IV drip, and given IV paracetamol. I would like to refer him to the on-call surgical team for further management and probable appendicectomy."
XI. Summary & Further Reading
Top 3 Takeaways:
Suspect appendicitis in any patient with RIF pain, especially with anorexia and migratory symptoms.
Never miss an ectopic pregnancy. Do a UPT on every female of childbearing age with abdominal pain.
Early referral to the surgical team is key. Do not delay once you have a reasonable suspicion.
Key Resources:
UpToDate: Acute appendicitis in adults: Clinical manifestations and differential diagnosis
Amboss: Acute Appendicitis
StatPearls: Appendicitis
Malaysian National Antimicrobial Guideline (for antibiotic choices): Ministry of Health NAG - Gastrointestinal Infections
