Determining if clubbing is present
Most physicians are aware of Shamroth sign, and use it to evaluate for clubbing. Shamroth sign is the loss of the diamond that is created by placing the back surfaces of opposite terminal phalanges together.
I have found that it’s easier to diagnose mild clubbing by looking at the finger in profile. If the ratio of the distal phalangeal depth compared to the depth across the distal interphalangeal joint is greater than 1:1, then clubbing is present.3
Pearls
1. Have the patient try yawning to better see the pharynx without using a tongue blade.
2. Try the technique of auscultatory percussion to be more accurate at picking up pleural effusions.
3. Know your hematocrit, so you can better use color shade to assess for anemia.
4. Try looking at fingers in profile to pick up clubbing.
Dr. Paauw is professor of medicine in the division of general internal medicine at the University of Washington, Seattle, and serves as 3rd-year medical student clerkship director at the University of Washington. He is a member of the editorial advisory board of Internal Medicine News. Dr. Paauw has no conflicts to disclose. Contact him at imnews@mdedge.com.
References
1. Guarino JR and Guarino JC. Auscultatory percussion: A simple method to detect pleural effusion. J Gen Intern Med. 1994 Feb;9(2):71-4.
2. Strobach RS et al. The value of the physical examination in the diagnosis of anemia. Correlation of the physical findings and the hemoglobin concentration. Arch Intern Med. 1988 Apr;148(4):831-2.
3. Spicknall KE et al. Clubbing: an update on diagnosis, differential diagnosis, pathophysiology, and clinical relevance. J Am Acad Dermatol. 2005 Jun;52(6):1020-8.