How time can be used as a diagnostic tool

I can’t remember which lecture it was, or even just when in my first two years of medical school the lecture was given, but I do remember how the concept struck me as really important.

The gist of the message was that the timing of onset of a patient’s symptoms is a key part of understanding the nature of the patient’s diagnosis. Symptoms from a neoplasm come on gradually, tend to be persistent and progressively more intense.  Symptoms of an infection tend to come on more quickly, evolving over hours to days, and usually becoming progressively worse at least initially.  Symptoms of ischemia — of an organ not being perfused by freshly oxygenated arterial blood — tend to come on over a minute or more, last at least several minutes, and resolve gradually.

Understanding this natural timing of various types of processes can help differentiate the nature of symptoms.  Fleeting chest pains that last a second or two almost never are related to coronary ischemia, because the heart muscle does not respond that quickly to lack of circulation, either in the onset of pain or the resolution of pain.  A mass in the neck that comes up overnight is rarely a cancer, because cancer cells just don’t multiply that fast, whereas the inflammatory response to infection can lead to enlargement of lymph nodes very quickly.  The headache from a ruptured cerebral aneurysm comes on suddenly, whereas a migraine headache builds up over minutes to hours.

Another use of time is to watch to see the progression of symptoms after a patient initially comes to the physician.  Any times one of the decisions at the initial visit for a patient complaint is to decide between doing diagnostic testing right away, and waiting for a few days or weeks to see how the symptoms and physical findings progress. This wait and see approach is sometimes the best approach to figuring out what is causing the problem, i.e. making a diagnosis.  A good example of this is in the patient who comes complaining of a twisted knee with swelling.  After initial assessment, and deciding that there is no emergent surgical problem, the options might be:

  1. Use ice, ibuprofen, an ace wrap, and rest along with gradually increasing activity and some exercises and to reevaluate the knee in 2 weeks.
  2. Send the patient for an x-ray and if no abnormalities get an MRI to see if there is a meniscus injury and to define the extent of ligamentous injury.

The big difference is often just cost and the desire to know what’s wrong, i.e. have a firm diagnosis, to avoid living with uncertainty for a while.  When it’s other people’s money, as it is in our system much of the time, spending money to avoid living with uncertainty is very tempting.  I don’t recall the last time an uninsured patient urged me to please quickly spend their own money to order an expensive test that had a good chance of being avoided by using time as a helpful diagnostic tool.

Patients intuitively use time in their decision making routinely.  I often hear the comment, “I would not have come in for this nasal congestion, but it’s just gone on too long to be just a cold.” Similar comments with pain and swelling from ankle sprains, diarrhea, hives, pink eye, and similar problems bring patients in to see daily. Sometimes their concerns are also concerning to me as their physician, and warrant diagnostic evaluation or therapeutic intervention.  Other times more time is needed to allow the self limited problem to run its natural course.

Time; you can’t buy any more of it, but it’s use as a diagnostic tool is often free.

Edward Pullen is a family physician who blogs at

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  • Chris Johnson

    Indeed. Tincture of time can be an active therapy, not merely a passive one.

  • David Hager, M.D.

    I’ve reviewed thousands of community MH records in the process of providing services in a correctional setting. What is seen in jail can be very different from what lives in the community mental health record.



    For example, three days is a common length of stay figure upon which funding contracts are based for community mental health center crisis units. How much diagnosis is possible for a dysphoric, agitated, active substance abuser within three days?

    Add to that the fact that Medicaid usually doesn’t pay for primary substance abuse diagnoses. Result = major mood disorder diagnosis.

    However, the same people often later meet admission criteria for … jail. Length of stay there tends to be longer than three days, affording sufficient time to determine whether a major mood disorder is actually present.

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