McBurney's Sign in Appendicitis Diagnosis
Point tenderness between the umbilicus and the anterior-superior iliac spine is known as McBurney's sign, which is a classic indicator of appendicitis. 1, 2
Understanding McBurney's Sign
- McBurney's sign refers to tenderness at McBurney's point, which is located at the junction of the lateral and middle thirds of a line joining the umbilicus with the right anterior superior iliac spine (ASIS) 2
- This sign was first described by the New York surgeon Charles McBurney in 1889, who noted that the location of greatest pain in appendicitis was "between an inch and a half and two inches from the anterior spinous process of the ilium on a straight line drawn from that process to the umbilicus" 1
- Despite being a classic sign, studies show that only about 35% of appendix bases actually lie within 5 cm of McBurney's point, with 75% of appendix bases located below and medial to a line joining the umbilicus with the right ASIS 2
Clinical Significance in Appendicitis Diagnosis
- McBurney's sign is part of the classical presentation of appendicitis, which includes periumbilical pain that migrates to the right lower quadrant, anorexia, nausea/vomiting, and fever 3, 4
- This sign is considered one of the best physical examination findings for ruling in acute appendicitis in adults, along with right lower quadrant pain and abdominal rigidity 5
- The classic diagnostic sequence includes initial vague epigastric or periumbilical pain, followed by anorexia, nausea or vomiting, migration of pain to the right lower quadrant, and finally the development of McBurney's sign 6
Differentiation from Other Signs
- McBurney's sign (tenderness at McBurney's point) should be distinguished from other physical examination findings in appendicitis evaluation: 5
- Psoas sign: pain with extension of the right hip (suggests retrocecal appendicitis)
- Obturator sign: pain with internal rotation of the flexed right hip (suggests pelvic appendicitis)
- Rovsing sign: pain in the right lower quadrant when palpating the left lower quadrant
Diagnostic Algorithm
- Clinical assessment including evaluation of McBurney's sign should be combined with laboratory studies and appropriate imaging for comprehensive diagnosis 7, 3
- Risk stratification tools such as the Alvarado Score or Pediatric Appendicitis Score can help determine the need for imaging studies 5, 6
- When McBurney's sign is positive, imaging confirmation is recommended: 7
- Ultrasound is typically the first-line imaging modality, especially in children and women of childbearing age
- CT scan without oral contrast offers high sensitivity (85.7-100%) and specificity (94.8-100%) for appendicitis diagnosis
- MRI shows excellent diagnostic performance with high sensitivity and specificity, particularly useful in pregnant patients
Clinical Pearls and Pitfalls
- Despite its historical significance, McBurney's sign may not be present in all cases of appendicitis, as the appendix location can vary significantly between individuals 2
- Atypical presentations are particularly common in young children and may lead to delayed diagnosis and higher risk of perforation 4
- Over-reliance on McBurney's sign alone may lead to missed diagnoses, as studies show that less than half of all patients with appendicitis have tenderness maximal over McBurney's point 2
- The presence of McBurney's sign should prompt consideration of surgical consultation to reduce the risk of perforation, which occurs in 17-32% of patients with acute appendicitis 5