McBurney's Point Location
McBurney's point is located at the junction of the lateral and middle thirds of a line drawn from the umbilicus to the right anterior superior iliac spine (ASIS), which translates to approximately 1.5 to 2 inches (3.8 to 5 cm) from the ASIS along this line 1, 2.
Anatomical Description
The classic surface marking, described by Charles McBurney in 1889, represents the point of maximal tenderness in acute appendicitis. Specifically:
- Starting point: Umbilicus
- Ending point: Right anterior superior iliac spine (ASIS)
- McBurney's point location: At the junction where the lateral third meets the middle third of this line
- Distance from ASIS: Between 1.5 and 2 inches (approximately 3.8 to 5 cm) 2
Important Clinical Caveat
The actual appendix base location varies significantly from McBurney's point in the majority of patients. Research demonstrates that only 35% of appendix bases lie within 5 cm of McBurney's point, and 15% are located more than 10 cm away 1. Furthermore, 75% of appendix bases are positioned below and medial to the umbilicus-to-ASIS line 1.
This anatomical variability explains why less than half of patients with appendicitis have maximal tenderness precisely at McBurney's point 1. The wide distribution of actual appendix locations means that while McBurney's point remains a useful historical landmark for initial examination, clinicians should not rely exclusively on point tenderness at this specific location to rule in or rule out appendicitis.
Practical Application
When examining for suspected appendicitis, palpate the entire right lower quadrant rather than focusing solely on McBurney's point. The preferred location for procedures like paracentesis in the right lower quadrant is 2 finger breadths (3 cm) cephalad and 2 finger breadths medial to the ASIS 3, which differs slightly from McBurney's point and accounts for anatomical safety considerations.