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The Stethoscope Is Just A Tube

When teaching a pair of junior medical students at the bedside I was reminded of a widespread misconception amongst medical undergraduates (and perhaps postgraduates?) with regards to clinical examination.

Perhaps it originates from the stethoscope’s iconic status as the doctor’s tool of diagnosis, but this misconception is that the stethoscope is, on its own, at all particularly useful.

It may come as a comforting sight for the patient – to see the doctor standing before them with their stethoscope around their neck. Likewise for medical students looking up to their role models it is likely to serve as an emblem of professionalism and clinical prowess.

The stethoscope however, is just a tube.

As I observed these two students performing history and examination I was struck by the usual recourse to checklist questions, as opposed to skillful hypothesis-testing. This is quite normal and typical of students at this stage of training.

When they proceeded to clinical examination (a cardiovascular examination) I noticed both candidates would stand at the end of the bed to perform general observation, and then immediately apply the stethoscope to the patient’s chest.

The more well practiced amongst you will be thinking ‘but what about inspection, palpation, percussion (and then) auscultation?’. Indeed, these candidates were certainly unpracticed but I feel that their immediate jump to using the stethoscope reflects a wider misconception about clinical assessment.

The stethoscope, like clinical examination in general, is not a stand-alone assessment tool with the magical ability to reveal the underlying problem. If it is not used in conjunction with a solid problem-solving strategy (and a solid preceding history) its use is academic at best.

Lets consider the patient case in question to demonstrate this point. The students both identified that the patient had a murmur on clinical examination, though neither could confidently establish whether this was systolic or diastolic. Of course, with sound clinical examination skills one should be able to establish where in the cardiac cycle a murmur is. I would argue also that with sound clinical history-taking skills one should be able to establish what kind of murmur to expect on clinical examination. The key word here is to expect.

For example, this gentleman complained of a history of intermittent palpitations that were irregularly irregular in nature alongside a history of exertional shortness of breath and ankle swelling. There was a past medical history of infective endocarditis for which he had received a prolonged course of antibiotics.

Therefore based on this clinical history we should suspect:

  1. Heart failure
  2. Atrial fibrillation
  3. Increased risk of heart valve lesion

It is this appraisal of historical findings that must occur prior to physical examination, before we lay hands on the patient, and certainly before the stethoscope is used.

Given that the mitral valve is one of the most commonly affected valves in infective endocarditis we should expect to see, feel, and hear evidence of a mitral valve lesion in this patient.

Therefore the following physical signs should be thought of during the history, and then sought during examination:

  1. Irregularly irregular pulse (atrial fibrillation commonly occurs in mitral valve pathology due to the resultant left atrial dilatation)
  2. Malar flush (mitral stenosis may have occurred due to his episode of endocarditis)
  3. Raised JVP (reflecting congestive cardiac failure)
  4. Palpable thrills (especially over mitral area)
  5. Thrusting apex (reflecting LV volume overload which may occur in mitral regurgitation)
  6. Tapping apex (reflecting a palpable S1, which may occur in mitral stenosis)
  7. Added heart sounds (i.e. a third or fourth sound due to heart failure)
  8. A pansystolic murmur radiating to the axilla (mitral regurgitation may have occurred due to the history of endocarditis)
  9. A mid-diastolic murmur heard at the mitral area using the bell in left lateral position (mitral stenosis, again due to endocarditis)
  10. Crackles over the lung bases (pulmonary oedema can occur due to any form of mitral valve lesion)
  11. Ankle swelling and sacral oedema (reflecting CCF)

This is not an exhaustive list of clinical examination findings, but I hope it illustrates how we should anticipate what to find on examination, based on the history we have elicited.

So in summary, not only should the junior medical student initially perform an exhaustive checklist of physical examination manoeuvres, as they become more skilled they should anticipate expected findings, and as they become expert only seek those expected findings.

This helps to ensure that all physical signs are appreciated in their true context. Many patients will have physical signs that do not reflect significant pathology or that are unrelated to the presenting complaint. If we attach too much importance to physical signs out of their true context we risk making an incorrect diagnosis. What is the significance of a small lump found on a whole body CT scan of a healthy person with no symptoms to complain of?

What is the significance of trivial focal lung crackles in a patient with clinical features of large pulmonary embolism? In the absence of clinical features of infection or heart failure such crackles may be nothing more than a diversion.

Remember that the diagnosis in most cases is in the history, and physical examination serves to confirm/refute what we should already suspect. Physical examination is not a stand-alone assessment tool, and if it reveals a diagnosis you did not already suspect then you probably needed to take a more detailed history.

A stethoscope is just a tube of plastic with a diaphragm at one end and your eardrums at the other. The important stuff happens beyond your eardrums!

2 thoughts on “The Stethoscope Is Just A Tube

  1. I enjoyed reading your article whilst Sophia was interrupting with conversation ! I agree that the clues are in the story … And a good clinician is one who asks the right questions and gaining the salient positives and negatives .

    In psychiatry and probably in general practice , knowing the patient and their history is so important – the doctor patient relationship is key to therapeutic success …

    1. Hi Tahira – sorry only just read this comment – my website is full of spam comments so I never check them! Thanks for reading!

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