Fluctuant

Fluctuant is an adjective used in clinical medicine to describe a soft, compressible swelling that yields to pressure and contains liquid content. On palpation it feels like a fluid-filled bubble that can be indented with finger pressure and may rebound after release. The term implies the presence of a fluid collection, such as pus in an abscess, serous fluid in a seroma, or blood-tinged fluid in a hematoma. It is contrasted with solid, firm, or tense masses that do not yield to pressure.

Fluctuant swellings are commonly associated with abscesses in soft tissues or in dental infections, where the collection of pus produces tenderness, warmth, and surrounding inflammation. They may also occur after surgical procedures as seromas or in cystic lesions.

Evaluation includes careful palpation to assess content and tenderness, and imaging such as ultrasound to confirm fluid within a lesion when the diagnosis is uncertain. If a fluctuant abscess is suspected, definitive management is drainage, often via needle aspiration or incision and drainage, with antibiotics as indicated by systemic signs or surrounding infection. Seromas or hematomas may be managed with observation, compression, or drainage if enlarging or symptomatic.

Etymology: fluctuant derives from Latin fluctus, meaning a wave or surge, with the suffix -ant indicating a characteristic.