A stethoscope is a diagnostic instrument used by medical professionals to listen to a patient's chest cavity, heart and various pulse points. Doctors use these tools as part of a non-invasive examination procedure, commonly listening for sounds of congestion in the lungs and irregular heartbeats. Nurses may also use them to listen for restored blood flow during blood pressure checks, among other procedures.
For centuries, physicians would literally place their ears directly on a patient's chest or back as part of an examination, a procedure medically called immediate auscultation. It was not unusual for these healthcare professionals to contract communicable diseases through such intimate contact with sick patients. In the early 19th century, a young French physician named Rene Theophile Hyacinthe Laennec found examining female patients this way to be a little discomforting. In 1816, Dr. Laennec fashioned a cylinder from several sheets of paper and used it to examine a young female patient. He discovered that internal sounds could be isolated and amplified through a tube, making examinations less intrusive and easier to interpret.
Dr. Laennec perfected his listening device using wooden tubes turned on a lathe. He wrote an important medical treatise on the new examination method, called mediate auscultation, in 1819. Colleagues convinced him to name his invention the stethoscope, after the Greek words for "chest" (stethos) and "to view" (scope). Laennec himself would die from tuberculosis in 1826.
Modern stethoscopes consist of a bell-shaped device with a clear plastic diaphragm, a length of rubber tubing, and a hollow metal headset with dual plastic earpieces. The disk-shaped diaphragm is placed directly on a patient's chest or back. As the patient takes deep breaths, sounds from the chest cavity are amplified through the diaphragm and bell. These sounds travel through the hollow rubber tube and headset, reaching the examiner's ears through tight-fitting earpieces. Any abnormal sounds, such as fluid retention or constriction of the airways, can be easily detected by trained medical professionals.
Heartbeats may also be heard through this device, although the diaphragm for a heart exam may be different from the ones used for respiratory exams. Different adjustments can filter out unwanted sounds in order to concentrate on a specific concern. Healthcare professionals may use a heart monitor to get an electronic reading of a patient's heart rate, but a stethoscope can reveal other abnormalities not easily measured by electronic equipment.