Finger clubbing (digital clubbing) is a clinical sign in which the fingertips and toenails become abnormally curved, with thickening of the tissue beneath the nail, giving a characteristic bulbous shape to the fingertips. The angle between the nail and the nail fold (Lovibond’s angle) exceeds 180 degrees. Clubbing develops over months to years and is associated with a range of underlying diseases.
In cardiovascular medicine, clubbing is classically associated with cyanotic congenital heart disease, where chronically low blood oxygen levels stimulate changes in the fingertips. It can also occur in infective endocarditis, particularly subacute bacterial endocarditis. The precise mechanism involves chronic hypoxia triggering increased vascularity and connective tissue proliferation in the fingertip dermis.
Other medical causes of clubbing include chronic respiratory diseases (lung cancer, bronchiectasis, empyema), hepatic cirrhosis, inflammatory bowel disease, and mesothelioma. Idiopathic (primary) clubbing also exists. The appearance of new clubbing in a previously unaffected patient should always prompt investigation for an underlying cause.
Clubbing is assessed clinically by inspecting and palpating the fingernails. The presence and severity of clubbing is noted as part of a comprehensive cardiovascular and respiratory examination. In children with complex congenital heart disease, the degree of clubbing may reflect the severity and duration of chronic oxygen desaturation.
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