What might I expect?: Laennec’s stethoscope changed diagnostic capabilities (2024)

Nearly every health-care professional has the handy instrument draped over their neck for frequent use. Placing the tips of the stethoscope into their ears, the nurse or physician places the chest piece of the stethoscope (also called diaphragm) on the patient’s chest and listens carefully. In the search for diagnoses, the stethoscope has a long history, dating back to its invention in France in 1816.

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French physician René Theophile Hyacynthe Laennec (1781-1826) studied medicine with professional physicians at Hôpital de la Charité. They taught their avid student the modern techniques of the era. Qualified in 1804 at age 23, Laennec practiced medicine at Hôpital Necker in Paris. He chose cardiac and respiratory medicine as his specialty, building on auscultation skills learned from his professor, Dr. Jean-Nicolas Corvisart des Marest.

Assessing lungs by auscultation—listening—doctors would strike “the fingers of one hand over the fingers of the other hand,” said editor K. Ernstmeyer et al in Nursing Skills, 2nd Edition, 2023. “Dull sounds are heard with high-density areas, such as pneumonia or atelectasis, whereas clear, low-pitched, hollow sounds are heard in normal lung tissue.” (Atelectasis is partial or complete collapse of the lung.) As well as tapping, Laennec used the traditional technique of putting his ear onto his patient’s chest to hear the bodily sounds. He puzzled over how to improve the methods of assessment.

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Walking through a park in late 1816, the doctor observed children “who put their ears at the ends of a wooden bar and transmitted tapping signals to each other,” noted B. Luderitz in “The discovery of the stethoscope by T.R.H. Laennec” in Journal of Interventional Cardiac Electrophysiology, 2009. Examining a young woman who exhibited symptoms of cardiac disease, Laennec was confronted with a problem. Social standards prevented him from putting his ear onto the woman’s chest to listen to her heart and lungs. Recalling the youngsters’ game, the innovative Laennec devised a plan.

“To preserve her modesty and spare himself the embarrassment of placing his ear directly on her chest to listen to her heart, Dr. Laennec rolled a piece of paper into a tube and used it as a barrier device.” according to Museum of Health Care at Kingston Blog. Avoiding awkwardness, his paper tube “improved on the direct practice of listening to chest sounds and even amplified the sound of the heart.” Laennec called his invention “cylinder” then changed it to “stethoscope.” (In Greek, ‘stetho’ means chest, and ‘scope’ is to view.)

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“The result has been, that I have been enabled to discover a set of new signs of diseases of the chest, for the most part certain, simple, and prominent, and calculated, perhaps, to render the diagnosis of diseases of the lungs, heart and pleura…,” writes Laennec in A Treatise of the Diseases of the Chest, London 1821.

Further developing his design, Laennec tested paper, cane, and wood for optimal acoustics. He settled on wood. Using a lathe and tools, the doctor created a monaural (one ear) stethoscope that could be taken apart, measuring 25 cm long by 3.5 cm in diameter. A musician, Laennec was equipped to make the device since he had experience carving wooden flutes with his lathe.

“The complete instrument, —that is, with the funnel-shaped plug in fixed,—is used in exploring the signs obtained through the medium of the voice and the action of the heart; the other modification, or with the stopper removed, is for examining the sounds communicated by respiration,” Laennec describes.

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Overworked with a heavy patient load while gathering information for a book plus inventing, Laennec’s body was weakened. While caring for sick patients, he contracted a disease. Taking time off from the hospital, the doctor worked on his book and also produced a number of stethoscopes. “Working with a lathe in his own room, he sought to prepare enough instruments so that whosoever bought the book might have a suitable implement with which to pursue his studies,” noted W.S. Thayer in On some unpublished letters by Laennec, 1920.

Patient assessments improved by leaps and bounds. Laennec’s stethoscope was the star, permitting immediate advancements in diagnoses, “so that it is sufficient to have heard them once to recognized them ever after,” Laennec writes in A Treatise. “Such are those which denote ulcers in the lungs, hypertrophia of the heart when existing in a great degree, fistulous communication between the bronchia and cavity of the pleura, &c.”

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Medical communities around the world readily accepted Laennec’s remarkable stethoscope. Human internal rumblings and functions could be grasped clearly. Laennec’s genius could not be left without challenges, facing piercing objections fired at him by some in the medical community. Laennec decisively fought back with firm evidence of his device’s advantages.

Publishing several medical books to share his vast knowledge, Laennec also “proposed terms for diseases as varied as cirrhosis, phlegm produced in asthma patients, prenatal intracavitary thrombus, spontaneous pneumomediastinum, among others,” stated Alejandro Donoso et al in Archivos Argentinos de Pediatria in 2020.

Admitted as a member of the Royal Academy of Medicine in 1823, Laennec returned to La Charité Hospital as professor of clinical medicine. He continued in publishing as editor of Journal de Médecine, Chirurgie, et Pharmacie. In 1824, he was awarded knighthood in the Legion of Honour, and that same year, the prominent physician married his housekeeper, Madame Jacqueline Argou. They had no children.

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By this time, Laennec’s long-term illness was diagnosed as phthisis—later called tuberculosis through advancements in laboratory medicine. Dr. René Laennec died on August 13, 1826 at age 45. He was buried in a cemetery at Brittany, a region he loved in northwest France. The prolific inventor, author, and physician packed much into the years of his short life, and his innovative stethoscope forever changed diagnostic capabilities.

The Museum of Healthcare at Kingston has a monaural wooden stethoscope in their expansive collection. Turned in maple, the device was made about two decades after Laennec’s original piece by Dr. Charles Williams, a British student of Laennec. “A trumpet shaped model with a removable earpiece,” the doctor’s “modifications provided improved acoustics and comfort for patients,” stated the Museum. The early stethoscope was “sensitive enough to hear a fetus in the womb.”

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Today’s stethoscope model was created in 1961 by Dr. David Littman, a cardiologist and professor at Harvard Medical School. With two earpieces, tubing, springs, and a chest piece composed of components, modern stethoscopes have zoomed into the digital age with “Bluetooth auscultation,” according to Stethoscope.com in “Anatomy of a Stethoscope: Everything You Need to Know.” The new system “allows doctors to auscultate their patients remotely—a concept that, even a decade ago, would have been difficult to conceive.”

Now, if only the chest piece could warm automatically…

Susanna McLeod is a writer living in Kingston, Ontario.

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