Bassler Sign: Place the patient in a sitting position with the examiner to the right of the patient. Palpate the lateral edge of the rectus abdominal muscle at a site located midway between the anterior superior iliac spine and umbilicus. With the thumb pushed posteriorly (1/2 the distance of the abdominal cavity), it is than swung to the right at a right angle to the downward pressure line. This maneuver pinches the appendix against the iliac muscle and structures producing pain or tenderness.
1913 – Anthony Bassler (1874-1959) described his method for compressing the appendix to assist in diagnosing chronic appendicitis. Bassler proposed that his test was most useful in obese patients and in patients where percussion could not identify the caecum.
When the thumb has been sunk about half-way down to the back of the abdominal cavity, it is swung to the right of the patient at a right angle to the downward pressure line. This pinches the appendix against the iliacus muscle and unyielding structures under and at the side of it, and usually elicits pain or tenderness. It is well, having done this in the mid-distance between the anterior superior spine and the umbilicus and not having obtained tenderness, to move the thumb down about one-half inch, performing it again, and so on downward until one has reached almost to the brim of the pelvis.
The same procedure on the left side serves as a control. By means of this method of downward and then right lateral pressure it is possible to elicit tenderness in the average case of chronic appendicitis.Bassler 1913
- Bassler A. Pinching the appendix in diagnosis of chronic appendicitis. American Journal of the Medical Sciences. 1913; 146(4): 204-208.
- Eponymythology: Appendicitis eponymous signs. LITFL
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