When Propriety Sparks Innovation: The Invention of the Stethoscope

Hello friends, and welcome back to the HHH blog. Today I’ve got a fun story and historical tidbit to share with you.

The stethoscope is probably the only instrument that is common to all doctors. In fact, some say it has even surpassed the caduceus symbol as the universal icon of doctors and medical care. However, I had never fully understood the significance of the instrument and the impact that it made on the medical profession until I studied for this post.

The part of the story that sparked my interest was the way in which the innovation came about. Prior to 1816, doctors could only detect a patient’s heartbeat by either holding a hand over the patient’s heart, or placing their ear to the patient’s chest and listening intently for a few moments. As you can imagine, this was probably not terribly efficient. However another problem arose for a young, single, French physician who was called upon to see a young woman who was displaying symptoms of heart disease. When 35 year old Dr. Rene Theophile Hyacinthe Laënnec arrived, he realized that the age, sex and “plumpness” of the young lady would make propriety an issue for him to use the traditional methods of examination. It didn’t seem appropriate to feel for the heartbeat with his hand, or press his ear to her chest to listen for it. Instead, he came up with another idea. He described the encounter as follows:

I recalled a well known acoustic phenomenon: if you place your ear against one end of a wood beam the scratch of a pin at the other end is distinctly audible. It occurred to me that this physical property might serve a useful purpose in the case I was dealing with. I then tightly rolled a sheet of paper, one end of which I placed over the precordium (chest) and my ear to the other. I was surprised and elated to be able to hear the beating of her heart with far greater clearness than I ever had with direct application of my ear. I immediately saw that this might become an indispensable method for studying, not only the beating of the heart, but all movements able of producing sound in the chest cavity. ~Translated from French by John Forbes, 1834

This discovery was a breakthrough for Laënnec, because not only had the simple device worked, it had projected the sound and made it clearer than direct auscultation alone. Laënnec spent the next three years experimenting with different materials and perfecting his design. Not only did he listen to heartbeats, but he could also listen more easily to other body sounds such as the raspy lungs of a patient with pneumonia.

Below is the design he came up with. It involved a hollow wooden dowel about 3.5cm in diameter and about 25cm long. The dowel was then fitted with a plug to listen to the patient, which could be detached to make it more portable.