Doctors have been listening to the sounds our bodies make for years. Before the invention of stethoscopes, they simply put their ears to their patients' chests or abdomens. The technical term for this diagnostic method is auscultation.
What Is Auscultation?
The inventor of the stethoscope, Rene Laennec, disliked putting his ear on his patients' chests. He tried using a paper funnel and found that it amplified chest sounds, making them easier to hear. Later users improved on his simple stethoscope design, creating stethoscopes similar to the one your doctor may use today.
Doctors and other healthcare still evaluate the sounds made by the heart, lungs, and intestines, watching for:
- Frequency. Is the sound high or low pitched?
- Intensity. How loud is the sound?
- Duration. How long does the sound last?
- Number. Is the sound repeated?
- Quality. How would you describe the sound?
Auscultation is a valuable diagnostic tool because it is safe and noninvasive. It can also be done at a moment's notice, since most healthcare providers have their stethoscopes close at hand.
What Are the Types of Auscultation?
The three major types of auscultation are heart, lung, and abdominal. Doctors can also listen to your arteries, especially those in the kidneys, neck, and abdomen. Auscultation of the arteries may help doctors detect poor circulation or blockages.
How Do Doctors Perform Heart Auscultation?
You've probably heard your own heart beating. There are two phases to a heartbeat. The lub, also known as S1, occurs when the mitral and tricuspid valves close. The dub or S2 occurs when the aortic and pulmonary valves close.
Doctors usually place their stethoscopes in four different positions on the chest wall. Each spot is best for hearing a particular heart valve. Besides hearing the sounds of the valves closing, doctors can hear sounds created by blood flow and the vibration of heart tissues. Their job is then to separate sounds that are normal from those that show disease or malfunction.
A swishing sound may indicate a heart murmur, which can either be benign or serious. Doctors may also hear a sound like the rubbing together of two pieces of leather. This sound may point toward pericarditis, an inflammation of the sac surrounding the heart.
When listening to the lungs, on the other hand, doctors usually start by placing the stethoscope on the front of the chest on one side. They move the stethoscope downward, then check the other lung. They then move to the back and check both lungs from the posterior. As they work, they compare the sounds made by the two lungs and the way the lungs sound from the back and from the front.
When listening to your lungs, your doctor may use the triangle of auscultation, a place on your back where three muscles meet. Your doctor may ask you to lean forward and cross your arms so that these muscles stretch, allowing lung sounds to be heard more clearly.
When performing lung auscultation, doctors will listen to at least one breath cycle. Some sounds are expected to be present as you breathe in (inspiration) and some as you breathe out (expiration). Others are heard during both parts of the breath cycle.
Your doctor may ask you to speak during the exam. Vocal qualities heard through the stethoscope can also help with a diagnosis.
Besides normal breath sounds, doctors may hear a variety of sounds, including:
- Wheezes. This high-pitched hissing noise can indicate asthma, chronic obstructive pulmonary disease (COPD), or fluid in the lungs.
- Squawks or squeaks. These short wheezes occur when you breathe in. They can be caused by several conditions.
- Crackles. Fluid in the airways causes these sounds, also called rales. The cause may be COPD, a lung infection, or a heart condition.
- Pleural rub. Compared to sandpaper rubbing together, this sound indicates a problem in the pleura, the membranes surrounding the lungs.
- Stridor. Problems in the upper part of the respiratory system cause stridor: a loud, high-pitched sound.
Why Do Doctors Auscultate the Abdomen?
Your doctor may also use the stethoscope to listen for sounds that your intestines make. These sounds can show problems including:
- Constipation or slow movement of waste through the intestines
- Diarrhea or other intestinal distress
- Obstruction of the bowels
- An ileus, a condition that causes the bowels to stop working
If your intestines are working properly, they make gurgling noises every 5 to 10 seconds.
What About New Technology?
Traditional auscultation has three significant problems. First, the sounds are very soft. If the doctor is in a noisy place or doesn't have good hearing, auscultation is not very helpful. Second, doctors can't easily record or share the sounds, so the results are usually the opinion of one person. Third, the results can't be stored.
Electronic stethoscopes offer solutions to all three of these problems. Electronic stethoscopes amplify the sounds beyond what a simple stethoscope can do. Some models can convert the sounds to a digital file for easy sharing and storage. This means doctors can share the results of auscultation with others at a later time or in a different geographic location. Such digital files are very important in the practice of telemedicine.
Some cardiologists also use a device that combines the stethoscope and electrocardiogram (EKG). That way, doctors can see what the heart is doing while listening to how the heart sounds.
Is Auscultation an Outdated Technique?
As scientists have developed new technologies, medical schools have put less emphasis on teaching auscultation. Some doctors feel it is still a worthwhile skill, though. A stethoscope can provide valuable information when other equipment is unavailable. The results of auscultation can also indicate which tests might be most helpful, eliminating unnecessary tests. However, for auscultation to be effective, doctors must be well-trained, experienced, and willing to spend the time to listen carefully.