Definition

McBurney's Point is the surface anatomical marking for the base of the appendix.

• Location: It lies one-third of the distance from the Anterior Superior Iliac Spine (ASIS) to the Umbilicus.
• Significance: Maximal tenderness here is highly suggestive of appendicitis (Localized Peritonitis).

History

Named after Charles McBurney (1889), an American surgeon who described the point of "greatest tenderness" in acute appendicitis. Before McBurney, appendicitis was often called "Perityphlitis" and treated conservatively (often fatally).

The appendix is a blind-ended tube.

1. Obstruction: Usually by a Faecolith (hard pooh stone) or Lymphoid Hyperplasia (after viral infection, common in kids).
2. Distension: Mucus secretion continues. Pressure rises.
3. Visceral Pain: The distended appendix stretches autonomic fibers (T10). Pain is felt in the Umbilicus (Midgut referal).
4. Inflammation: Bacteria multiply (E. coli, Bacteroides). Transmural spread.
5. Somatic Pain: The inflamed appendix touches the parietal peritoneum at the RIF. Pain migrates to McBurney's Point.
6. Perforation: Pressure > Venous pressure -> Ischemia -> Gangrene -> Burst. (Pain may briefly improve, then generalized peritonitis sets in).

1. McBurney's Tenderness: Point tenderness in RIF.
2. Rovsing's Sign: Palpation of the LIF causes pain in the RIF (Gas displacement distends the inflamed caecum?).
3. Psoas Sign (Retrocaecal): Pain on extension of the right hip (stretches Psoas muscle).
4. Obturator Sign (Pelvic): Pain on internal rotation of the flexed right hip.
5. Cough Tenderness: Ask the patient to cough. If they wince and point to RIF = Peritonitis (Dunphy's Sign).

A clinical rule to stratify risk.

• Score <3: Unlikely. Discharge.
• Score 4-6: Equivocal. Scan (CT/US). Observe.
• Score 7-10: Probable. Surgical consult.

Gynaecological (Females)

• Ectopic Pregnancy (Missed period, shock).
• Ovarian Cyst Rupture/Torsion (Sudden onset).
• PID (Vaginal discharge, bilateral pain).
• Mittelschmerz (Ovulation pain).

Medical

• Mesenteric Adenitis: Viral history, high fever, enlarged nodes on US. Common in kids.
• Gastroenteritis: Diarrhoea prominent. Vomiting precedes pain.
• Terminal Ileitis: Crohn's disease, Yersinia.
• Right Sided Divertculitis: Rare in Caucasians, common in Asians.
• Meckel's Diverticulitis: Rule of 2s.

"You have Appendicitis. A small tube on your bowel is blocked and infected. If we leave it, it might burst, which is dangerous. The standard treatment is keyhole surgery to remove it. You will have 3 small scars. It takes about an hour. You usually wake up with a sore tummy but feel better because the 'sick' pain is gone."

• Appendicolith / Faecolith: Calcified stone of faeces blocking the appendix. Visible on X-ray (10%).
• Carcinoid: Neuroendocrine tumour found incidentally in 1% of appendix specimens.
• Lanz Incision: Anatomical bikini-line incision used for Open appendicectomy. (Better cosmesis than Gridiron).
• Mesoappendix: The fatty mesentery carrying the blood supply (Appendicular Artery).
• Teniasmus: A feeling of incomplete defecation. (Seen in Pelvic Appendicitis).

Historically, a 20% negative rate was considered "good practice" (better to remove a normal appendix than miss a perforated one). In the CT era, this is unacceptable (should be <5%).

If the appendix looks normal... LOOK ELSEWHERE.

1. Mesenteric Adenitis (The Great Mimic)

• Patient: Child/Young adult. recent URTI.
• Pathology: Viral infection -> Enlarged mesenteric lymph nodes.
• Appearance: Appendix normal. Lots of large pink nodes in mesentery.
• Action: Do NOT remove normal appendix (controversial). Close.

2. Meckel's Diverticulum

• Rule of 2s: 2% of population, 2 feet from IC valve, 2 inches long, presents before age 2.
• Pathology: Remnant of Vitello-Intestinal duct. Contains Ectopic Gastric Mucosa -> Bleeding or Diverticulitis.
• Action: Always check the terminal ileum (2 feet) if appendix is normal. If Meckel's found -> Resect.

3. Gynaecological

• Endometriosis: "Chocolate spots" in pelvis.
• Ruptured Cyst: Fluid in Pouch of Douglas.

4. Crohn's Disease

• Terminal Ileitis: The terminal ileum is fat wrapping, red, and swollen ("Creeping Fat").
• Action: Do NOT remove appendix if the caecal base is involved (risk of fistula).

Variations in Position: The base of the appendix is constant (McBurney's). The Tip is wild.

1. Retrocaecal (65%): Behind Caecum. Flank pain.
2. Pelvic (30%): Hanging down into pelvis. Urinary/Rectal symptoms.
3. Sub-Caecal (2%): Below caecum.
4. Pre-Ileal (1%): In front of Ileum. Very dangerous (Rapid peritonitis).
5. Post-Ileal: Behind Ileum.

Blood Supply:

• Appendicular Artery: A branch of the Ileocolic Artery (from SMA). It is an "End Artery" (no collateral supply).
• Significance: If it blocks (thrombosis/pressure), the appendix infarcts (Gangrene) very quickly.

Case 1: The "Gastroenteritis" Trap

• Patient: 6yo female. Vomiting x3. Then pain. Diarrhoea x1.
• Diagnosis: GP diagnosed Gastroenteritis.
• Progression: Pain improved day 3 (Perforation). Day 4: Collapse. Septic shock.
• Lesson: Diarrhoea can occur in pelvic appendicitis ("Sympathetic diarrhoea" from rectal irritation). Pain before Vomiting = Surgical. Vomiting before Pain = Medical.

Case 2: The "Silent" Elderly

• Patient: 80M. "Not feeling right". Mild right sided ache.
• Exam: Abdomen "doughy". No guarding.
• CT: Large abscess. Perforated appendix.
• Mechanism: Immunosenescence. Weak muscles (no rigidity).
• Lesson: Low threshold for CT in elderly abdominal pain.

• CT CAP: CT Chest Abdomen Pelvis.
• Fecolith: See Appendicolith.
• Gridiron Incision: The muscle-splitting incision used for open appendicectomy at McBurney's point.
• Invagination: Inverting the appendix stump into the caecum (Burial) to prevent blowout.
• LIF: Left Iliac Fossa.
• Mandelung's Deformity: (Irrelevant here, but don't confuse anatomy!).
• Mucocele: A mucus-filled cystic dilation of the appendix (Pre-cancerous).
• Omentum: The "Policeman of the Abdomen". It wraps around the inflamed appendix to seal it off (Appendicular Mass).

1. Di Saverio S, et al. WSES Jerusalem guidelines for diagnosis and treatment of acute appendicitis. World J Emerg Surg. 2016.
2. Alvarado A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med. 1986.
3. Bhangu A, et al. (GlobalSurg). Safety of short-course antibiotic prophylaxis in appendicectomy. Lancet Infect Dis. 2018.
4. Salminen P, et al. Antibiotic Therapy vs Appendectomy for Treatment of Uncomplicated Acute Appendicitis: The APPAC Randomized Clinical Trial. JAMA. 2015.
5. CODA Collaborative. A Randomized Trial Comparing Antibiotics with Appendectomy for Appendicitis. N Engl J Med. 2020.
6. Andersson RE. Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Br J Surg. 2004.
7. Sauerland S, et al. Laparoscopic versus open surgery for suspected appendicitis. Cochrane Database Syst Rev. 2010.
8. Goyal N. Anatomy of the Appendix Vermiformis. Surgical Radiologic Anatomy. 2023.
9. Royal College of Surgeons. Commissioning Guide: Emergency General Surgery. 2017.
10. NICE NG51. Sepsis: recognition, diagnosis and early management. 2016.

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