Boas Sign
Introduction
Ismar Isidor Boas (1858–1938) was a renowned German gastroenterologist who first described Boas sign. He made significant contributions to the field by launching the world’s first gastroenterology journal, Archiv für Verdauungs-Krankheiten, in 1895, and founding the German Gastroenterology Society in 1920.[1]
Purpose
Boas sign is a clinical indicator of acute cholecystitis. It presents as an area of hyperaesthesia (increased skin sensitivity) over the posterior abdominal wall, typically between T11 and L1, extending from about 1 inch lateral to the midline to the posterior axillary line. This finding represents an example of referred pain from the inflamed gallbladder.[2]
Technique
Original description: Boas described tenderness at the level of the 12th thoracic vertebra, extending 2–3 fingerbreadths to the right, sometimes reaching the posterior axillary line.
Contemporary description: The sign is now elicited by lightly stroking the skin over the right infrascapular area or right upper quadrant. Increased sensitivity or pain compared to the left side indicates a positive Boas sign.[3]
Evidence
A single study reported the presence of this hyperaesthesia in 7% of patients undergoing cholecystectomy, suggesting it may be an infrequent but supportive sign of gallbladder inflammation.[4]
References
- ↑ Radiopaedia.org. Available at: https://radiopaedia.org/articles/boas-sign (Accessed: October 9, 2025).
- ↑ Prabhu S. Clinical signs and syndromes in surgery. Jaypee Brothers Medical Publishers; 2011.
- ↑ Salati SA, Alkhalifah K, Almousa AM. Eponymous signs of acute cholecystitis–a review. Saudi Medical Journal Students. 2023;3(2):44-55.
- ↑ Rastogi V, Singh D, Tekiner H, Ye F, Kirchenko N, Mazza JJ, Yale SH. Abdominal physical signs and medical eponyms: physical examination of palpation part 1, 1876–1907. Clinical Medicine & Research. 2018 Dec 1;16(3-4):83-91.