Stethoscope





Definition

The stethoscope is an instrument used for auscultation, or listening to sounds produced by the body. It is used primarily to listen to the lungs, heart, and intestinal tract. It is also used to listen to blood flow in peripheral vessels and the heart sounds of developing fetuses in pregnant women.


Purpose

A stethoscope is used to detect and study heart, lung, stomach, and other sounds in adult humans, human fetuses, and animals. Using a stethoscope, the listener can hear normal and abnormal respiratory, cardiac, pleural, arterial, venous, uterine, fetal and intestinal sounds.


Demographics

All health care providers and students learn to use a stethoscope.


Description

Stethoscopes vary in their design and material. Most are made of Y-shaped rubber tubing. This shape allows sounds to enter the device at one end, travel up the tubes and through to the ear pieces. Many stethoscopes have a two-sided sound-detecting device or head that listeners can reverse, depending on whether they need to hear high or low frequencies. Some newer models have only one pressure-sensitive head. The various types of instruments include: binaural stethoscopes, designed for use with both ears; single stethoscopes, designed for use with one ear; differential stethoscopes, which allow listeners to compare sounds at two different body sites; and electronic stethoscopes, which electronically amplify tones. Some stethoscopes are designed specifically for hearing sounds in the esophagus or fetal heartbeats.


Diagnosis/Preparation

Training

Stethoscope users must learn to assess what they hear. When listening to the heart, one must listen to the left side of the chest, where the heart is located. Specifically, the heart lies between the fourth and sixth ribs, almost directly below the breast. The stethoscope must be moved around. A health care provider should listen for different sounds coming from different locations. The bell (one side of the head) of the instrument is generally used for listening to low-pitched sounds. The diaphragm (the other side of the head) of the instrument is used to listen to different areas of the heart. The sounds from each area will be different. "Lub-dub" is the sound produced by the normal heart as it beats. Every time this sound is detected, it means that the heart is contracting once. The noises are created when the heart valves click to close. When one hears "lub," the atrioventricular valves are closing. The "dub" sound is produced by the pulmonic and aortic valves. Other heart sounds, such as a quiet "whoosh," are produced by "murmurs." These sounds are produced when there are irregularities in the path of blood flow through the heart. The sounds reflect turbulence in normal blood flow. If a valve remains closed rather than opening completely, turbulence is created and a murmur is produced. Murmurs are not uncommon; many people have them and are unaffected. They are frequently too faint to be heard and remain undetected.

The lungs and airways require different listening skills from those used to detect heart sounds. The stethoscope must be placed over the chest, and the person being examined must breathe in and out deeply and slowly. Using the bell, the listener should note different sounds in various areas of the chest. Then, the diaphragm should be used in the same way. There will be no wheezes or crackles in normal lung sounds.

Crackles or wheezes are abnormal lung sounds. When the lung rubs against the chest wall, it creates friction and a rubbing sound. When there is fluid in the lungs, crackles are heard. A high-pitched whistling sound called a wheeze is often heard when the airways are constricted.

When the stethoscope is placed over the upper left portion of the abdomen, gurgling sounds produced by the stomach and small intestines can usually be heard just below the ribs. The large intestines in the lower part of the abdomen can also be heard. The noises they make are called borborygmi and are entirely normal. Borborygmi are produced by the movement of food, gas or fecal material.


Operation

Some stethoscopes must be placed directly on the skin, while others can work effectively through clothing. For the stethoscopes with a two-part sound detecting device in the bell, listeners press the rim against the skin, using the bowl-shaped side, to hear low-pitched sounds. The other flat side, called the diaphragm, detects high-pitched sounds.

A stethoscope is used in conjunction with a device to measure blood pressure ( sphygmomanometer ). The stethoscope detects sounds of blood passing though an artery.

Examination with a stethoscope is noninvasive but very useful. It can assist members of the health care team in localizing problems related to the patient's complaints.


Maintenance

Stethoscopes should be cleaned after each use in order to avoid the spread of infection. This precaution is especially important when they are placed directly onto bare skin.


Aftercare

A stethoscope is a sensitive instrument. It should be handled with some care to avoid damage. It requires periodic cleaning.


Risks

There are no risks to persons being examined with a stethoscope. Users of a stethoscope may be exposed to loud noise if the bell is accidentally dropped or struck against a hard surface while the earpieces are in the user's ears.


Normal results

Stethoscopes produce important diagnostic information when used by a person with training and experience.


Morbidity and mortality rates

Normal use of a stethoscope is not associated with injury to either an examiner or a person being examined.

Alternatives

A tube formed by a roll of paper will function in the same manner as a stethoscope. This improvised instrument was the first form of the modern stethoscope invented by René Laënnec (1781-1826), a French physician. An inverted glass will also function as a stethoscope by placing the open portion on the surface to be listened to and the ear of the examiner on the bottom of the glass. Due to their shape, wine glasses with stems are more effective than flat-bottomed tumblers.

See also Physical examination .


Resources

BOOKS

Bickley, L. S., P. G. Szilagyi, and J. G. Stackhouse, eds. Bates' Guide to Physical Examination & History Taking , 8th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2002.

Blaufox, MD. An Ear to the Chest: An Illustrated History of the Evolution of the Stethoscope . Boca Raton, FL: CRC Press-Parthenon Publishers, 2001.

Duffin, J. To See with a Better Eye . Princeton, NJ: Princeton University Press, 1998.

Duke, M. Tales My Stethoscope Told Me . Santa Barbara, CA: Fithian Press, 1998.


PERIODICALS

Conti, C. R. "The Ultrasonic Stethoscope: The New Instrument in Cardiology?" Clinical Cardiology 25 (December 2002): 547-548.

Guinto, C. H., E. J. Bottone, J. T. Raffalli, et al. "Evaluation of Dedicated Stethoscopes as a Potential Source of Nosocomial Pathogens." American Journal of Infection Control 30 (December 2002): 499-502.

Hanna, I. R., and M. E. Silverman. "A History of Cardiac Auscultation and Some of its Contributors." American Journal of Cardiology 90 (August 1, 2002): 259-267.

Savage, G. J. "On the Stethoscope." Delaware Medical Journal 74 (October 2002): 415-416.


ORGANIZATIONS

American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. (913) 906-6000. http://www.aafp.org . E-mail: fp@aafp.org

American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007-1098. (847) 434-4000; FAX: (847) 434-8000. http://www.aap.org . E-mail: kidsdoc @aap.org

American College of Physicians. 190 N. Independence Mall West, Philadelphia, PA 19106-1572. (800) 523-1546, x2600 or (215) 351-2600. http://www.acponline.org .

American College of Surgeons. 633 North St. Clair Street, Chicago, IL 60611-3231. (312) 202-5000; FAX: (312) 202-5001. http://www.facs.org . E-mail: postmaster@facs.org


OTHER

British Broadcasting Company. http://www.bbc.co.uk/radio4/science/guessingtubes.shtml . (March 1, 2003)

Institution of Electrical Engineers. http://www.iee.org/News/PressRel/z18oct2002.cfm . (March 1, 2003)

McGill University Virtual Stethoscope. http://www.music.mcgill.ca/auscultation/auscultation.html . (March 1, 2003)

University of Minnesota Academic Health Center. http://www.ahc.umn.edu/rar/MNAALAS/Steth.html . (March 1, 2003)


L. Fleming Fallon, Jr., MD, DrPH

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?



Any member of a health care team participating in a physical examination uses a stethoscope. It is used to detect and transmit sounds created within the body.

QUESTIONS TO ASK THE DOCTOR



  • Are the sounds being heard normal or abnormal?
  • Have the sounds changed since the last examination?
  • Has a murmur, if present, changed in pitch or loudness?

User Contributions:

andrew
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Mar 10, 2008 @ 4:04 am
very nice post which really helps to understand.........

thanks a lot..

Best regards
andrew
alexander danjuma
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Jan 7, 2010 @ 8:08 am
Thank you for this product, I just want to enquire more on how the system can detect a problem on the patient bein examine,is it that the sound of the device varies from the normal sound or it will start after certain range of time? That is after certain count of the sound? please help me.
anela
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Oct 1, 2010 @ 6:06 am
very good article.But i have one question.could you say little about the physical functions of the stethoscope (based on what, what are his principle and recognition, etc. ..)?
Than you a loz :)Anela
victoria
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Nov 30, 2010 @ 7:19 pm
Do (medical billing and coding specialist)use stethoscopes? I am studing for M.B.C.S and they have yet to tell us.
jimmy osiemo
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Feb 20, 2011 @ 8:08 am
THANKS A LOT FOR THIS PRODUCT.MY QUESTION IS,WHATS THE RELATIONSHIP BETWEEN STETHOSCOPE AND BLOOD PRESSURE
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Apr 1, 2011 @ 8:08 am
I had a concussion on January 6, 2009. I have had several MRI and CT tests, because of middle, inner ear damage, including bones, cochlear, auditiory nerve, and brain damage close to the speech center.

The damage to my auditory system has resulted in a HUM, much like a diesel engine that I hear consistently, and people sound like "Donald Duck" and music is impossible to decipher.

My background is a B.S.E.E., of UND. I have made an stethoscope/amplifier/filter/oscilloscope/headphones chain with an Electret sensor microphone input. I have been able to observe the waveform that the stethoscope picks up all over my body, as well as my pulse at my chest and carotid arteries.

I have characterized the HUM (Which is a low frequency and loud) by first using the stethoscope and then taking a picture of the storage oscilloscope "Turbulence", or auscultation, then using Nyquist theory (Sampling at twice the rate of the highest component)to reveal the frequencies of
the HUM as well as the lower other frequencies.

Looking at the relationship of the HUM components picked up by the stethoscope, and matchingit to the frequencies of the keys of the piano, I was able to re-create the HUM for other people to hear. They can also hear it with another set of headphones, at the same time I am using headphones.

Much torment is stated on the Internet by people with this problem. I am preparing a paper which will reveal much of the testing. I have tested 12 people so far who have blood "Turbulence" similar to mine, but they do not "Hear" the HUM. The tests were done on appendages, chest, face, neck, wrists, etc.

My theory is that the normal people so not have a capillary/neuron transmission of undulation, which in my case, is severe due to my concussion.

Regards,

Gary Mortensen
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May 24, 2011 @ 2:02 am
''stethoscope detects whether sound produced by organs like heart are normal'' may i know how we use it when dealing with intestines?
Rishi Gupta
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Nov 14, 2012 @ 11:11 am
To learn how to use a stethoscope, I can recommend a few sites:
PracticalClinicalSkills
EasyAuscultation
Littmann

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