Understanding the Differences Between Different Types of Stethoscopes

Author: Nicole Adler   Date Posted:4 January 2018 

Ensuring that you have the correct stethoscope for the circumstances is critical to proper auscultation. While most medical students first stethoscope is likely to be a simple, basic acoustic model, increasing expertise and specialisation will require the use of a variety of designs, each with their own strengths, drawbacks and intended uses.

This guide is designed to give a broad overview of the most common variations of stethoscope on the market.

Acoustic vs Electronic

Broadly, stethoscopes will either be unpowered and operate on the principles of acoustics, or powered and relying on some alternative mechanism. Where an acoustic stethoscope will capture sounds made by the body in a diaphragm or bell as vibrations, there is no standardised mechanism for electronic stethoscopes. Different manufacturers utilise different technologies as transducers. While previously microphones were used in the chest piece, this was determined to result in too much ambient noise for the physician; piezoelectric crystals mounted to a metal shaft, as well as diaphragms produced with an electrically conductive inner surface are the current preferred technologies.[1] A key weakness of electronic stethoscopes is their sensitivity to background noise,[2] which must be accounted for by the physician.

The Need for Specialised Designs

Specific disciplines have evolved a need for more specialised stethoscopes. More experienced students and residents experienced in auscultation may consider making the switch to a cardiology or cardiovascular stethoscope. This type of stethoscope will provide better audibility of higher-frequency sounds[3], crucial for detecting subtler changes in the patient’s heart. Their increased response means that they are only suitable for physicians experienced in auscultation, as less skilled doctors may struggle to separate the sound they’re looking for from the background noise of the body.

Obstetricians, midwives and other physicians frequently rely on foetal stethoscopes – also referred to as Pinard horns in honour of their inventor Dr. Adolphe Pinard – for listening to the heartbeat of a foetus. These resemble a small trumpet and operate by placing the wide end of the device against the belly and listening through the narrow end. These compare unfavourably in randomised clinical trials against handheld Doppler foetal monitors, which determined that the latter were able to identify a greater number of foetal heart rate abnormalities in labour.[4]

Speak to colleagues and superiors in your field about the tools they use before making any purchase. For a range of high-quality stethoscopes, browse the range at Mentone Educational.

 


[1] Mangion, K. (2007). The stethoscope. Malta Med J, 19, 41-4.

[2] Ibid.

[3] Korhonen, P., Lukkarinen, S., Sepponen, R., Backman, J., Ruotoistenmaeki, H., & Rajala, K. (1996). Frequency response measurements on commercially available stethoscopes. Medical and Biological Engineering and Computing, 34, 91-92.

[4] Byaruhanga, R., Bassani, D. G., Jagau, A., Muwanguzi, P., Montgomery, A. L., & Lawn, J. E. (2015). Use of wind-up fetal Doppler versus Pinard for fetal heart rate intermittent monitoring in labour: a randomised clinical trial. BMJ open, 5(1), e006867.