听诊

Auscultation is the act of listening to sounds produced by the body during a physical examination. It allows clinicians to eavesdrop on the body's internal workings and gain important diagnostic information. Though historically performed with the examiner's ear directly on the patient's skin, René Laënnec invented the stethoscope in 1816, making auscultation a practical and socially acceptable diagnostic tool that remains inseparable from modern clinical practice.

A stethoscope has three basic parts: ear buds, tubing, and a chest piece. The chest piece typically has two surfaces—a diaphragm and a bell. The diaphragm, applied firmly against the skin, transmits high-frequency sounds like S1 and S2 heart sounds. The bell, applied lightly, transmits low-frequency sounds like S3 and S4. Some modern stethoscopes have a single-sided chest piece that functions as both, depending on pressure applied.

The diaphragm transmits high-frequency sounds when applied firmly against the skin. Firm pressure allows vibrations from within the patient to vibrate the diaphragm membrane, propagating sound through the air column into the examiner's ears. The bell transmits low-frequency sounds when applied lightly, acting as a cup that directly transmits sounds through the tubing. Pressing the bell firmly can stretch underlying skin, essentially converting it into a diaphragm.

Before patient contact, decontaminate the stethoscope with standard agents. Insert ear buds with tips pointing forward to create a seal reducing ambient noise. Confirm which chest piece side is active by gently tapping both surfaces. Rotate the piece until you hear a click to switch sides. Hold the chest piece in your dominant hand using one of two grips: supporting it between your second and third fingers with your thumb under the tubing, or between your thumb and second finger.

Throughout the patient encounter, use your unaided hearing to identify diagnostically useful findings like hoarse voice or grunting respirations. As you listen, consider the physiology and mentally picture the anatomy to parse simultaneous sounds. Train your mind to form visual representations of sounds heard, which helps characterize underlying pathology. Certain electronic stethoscopes allow recording and visual representation of findings, supporting deliberate practice.

Auscultation is used across multiple clinical settings, most commonly in examination of the chest, heart, abdomen, and vasculature. Specific auscultation techniques exist for pulmonary, cardiac, abdominal, and vascular examinations. Understanding anatomy and physiology of these structures helps clinicians parse the variety of sounds heard and make accurate diagnostic assessments. Through deliberate practice, auscultation becomes a powerful diagnostic tool.

Immediate auscultation, with the examiner's ear directly on the patient's skin, was standard for centuries but proved inadequate in nineteenth-century France due to social norms and poor diagnostic yield. René Laënnec invented the first stethoscope in 1816—a hollow wooden tube that allowed sound transmission while maintaining professional distance. Since then, the stethoscope has undergone many technologic advances and remains an essential tool in modern medicine.