Abklopfen

Abklopfen, in medical usage often synonymous with percussion, is a manual technique used during physical examination to assess the state of underlying tissues and organs by tapping on the body surface and listening to the resulting sounds and vibrations. The term derives from the German elements ab- “away” and klopfen “to knock.”

Technique and variants: Abklopfen can be indirect (indirektes Abklopfen), using a pleximeter finger placed on the skin and a plexor finger or small hammer to strike it, or direct (direktes Abklopfen), where the striking finger taps directly on the body surface. The examination can be performed with the patient in various positions, and the clinician evaluates the pitch, quality, duration, and intensity of the sound and compares corresponding regions.

Interpretation: Percussion notes are categorized by their characteristic sound. Resonant notes suggest air-filled structures (such as healthy lung tissue), dull notes indicate denser tissue or fluid (liver, heart, pleural effusion, ascites), tympanic notes reflect gas-filled areas (stomach, bowel), and flat notes occur over dense tissue like bone or muscle. In practice, abdominal and chest percussion helps delineate organ borders, detect abnormalities such as pneumothorax, consolidation, effusions, or liver enlargement, and complements other examination methods like Auskultation and palpation.

Other uses: Outside medicine, Abklopfen is also employed in non-destructive testing of materials, where tapping sounds reveal hollows, cracks, or defects.

See also: percussion (medical examination) and non-destructive testing.