Medical Practice

The basic three-step approach used by physicians in diagnosing disease involves taking a patient's history, performing a physical examination, and ordering laboratory tests and/or imaging procedures. These steps are discussed in-depth below:

History Taking

All the facts in the patient's medical history should be noted in the written record. The history can be recorded in one of two ways: (1) it can be recorded in chronological order, in which case recent events should be emphasized most; or (2) if a problem-oriented approach is used, the problems that are clinically most pronounced should be noted first. The nature of the symptoms should be in the patient's own words. In eliciting the history, the physician needs to be careful to avoid suggesting answers in the course of guiding the patient through the interview. It is important that careful attention be given to all the details of the interview, no matter how minor, since a seemingly small detail may be important in making the diagnosis.

More than an organized listing of symptoms, a well-written history, elicited during the interview, should also reveal something about the patient, in addition to the nature of the patient's disease. This information may be extracted from facial expressions, voice inflections, and the attitude that is evident during the discussion of the illness. Taking a history is a challenge since patients are highly subjective in their presentation and may also be affected by their past experience. In addition, there is a fear of disability or even death, as the impact of illness on one's family inevitably influences a person's account of the problem. Unfortunately, language or sociological obstacles, as well as failing mental recall, can, in some cases, very significantly interfere with the patient giving an adequate history. In such cases, the physician may have to seek the help of an interpreter or a member of the patient's family in order to obtain an accurate history. The physician's skill, knowledge, patience, and experience will greatly influence the quality of the history taken.

Obtaining a family medical history can be very helpful in short-term care and preventive health. The process of history taking also serves to establish or strengthen the physician-patient relationship. Patients should be put at ease and should be allowed to express their thoughts. The confidential nature of the information should be emphasized.

Physical Examination

Physical signs are objective and verifiable evidence of disease. Their significance is enhanced when these signs confirm a structural or functional change indicated by the patient's history. On occasion, the physical signs may be the only evidence of disease, especially if the history is not informative.

The physical exam should be carried out methodically and thoroughly. While the focus of the exam may be on the diseased area or organ, in a new patient the exam should cover the entire body. The results should be recorded at the time they are obtained. Skill in this area is required and comes with time.

Laboratory Tests

The increase in the number, type, and availability of laboratory tests has resulted in the increased reliance on this approach for the solution of clinical problems. It is essential to bear in mind that laboratory tests are often believed by physicians to be the final authority, regardless of possible fallibility of the tests, the individuals handling or interpreting them, or of the instruments. Laboratory data cannot replace observation of the patient. Both the expense and possibilities of misinterpretation of the lab tests ordered should be taken into account by the physician. Laboratory tests are rarely done individually, but rather as batteries (24 up to 40). The various combinations of lab tests are frequently quite useful. The thoughtful use of screening tests should not be confused with indiscriminate lab testing. Screening tests are useful because they enable the physician to obtain a group of lab results conveniently, utilizing a single specimen of blood, at relatively low cost. Biochemical measurements, together with simple lab tests, such as blood counts, urine analyses, and sedimentation rate often provide the principle clue to the presence of a pathological process. The physician must be alert for abnormalities in screening test results that may not indicate significant disease. An isolated laboratory abnormality on an otherwise well patient should not provoke an in-depth medical workup. The lab test itself may bear repeating to see if the results are reproducible. The physician can then determine whether the results are significant. Clinical judgment will determine how to proceed if this occurs.

Imaging Techniques

Over the past quarter of a century, the use of imaging techniques as a diagnostic method has become well established. This includes ultrasonography, a method of examination using soundwaves to visualize internal organs; computerized axial tomography (CAT); magnetic resonance imaging (MRI); and position emission tomography (PET). This major new diagnostic approach has frequently replaced invasive techniques that require insertion into the body of tubes, wires, or catheters or surgical biopsy. The latter are frequently painful and at times quite risky to the patient. While very valuable, imaging technique results need validation and are often extremely expensive. Therefore, this approach should be used judiciously, but not as a supplement to invasive techniques.