The HPI is the key to the diagnosis, starting with the chief complaint. The clinical evaluation (history plus physical examination) guides the selection of tests, which are obtained to confirm or rule out diagnoses suggested clinically, an aphorism widely known as “Sutton’s law.”

Willie Sutton, a legendary bank robber, escaped from prison three times and always returned to bank robbing. When asked why he robbed banks he gave what has become an iconic reply: “ … because that’s where the money is.”

The HPI orients the clinician to the patient’s problem and establishes an initial differential diagnosis. Of major importance is the temporal sequence and progression of symptoms.

Elements from the Review of Systems and the Past Medical History that are relevant to the patient’s complaint should be part of the HPI. Pertinent negatives should be enumerated. If not specifically stated, a negative cannot be inferred; it must be presumed that the question was not asked.

Symptoms that have a limited differential are particularly important.

Paroxysmal nocturnal dyspnea (PND), when classic, means left heart failure; by contrast, orthopnea has an extensive differential and is much less specific although it is also a manifestation of heart failure.

This distinction is only meaningful when the features of PND are known and understood: awakening from asleep after about 2 hours (usually around 2 AM) with shortness of breath, getting out of bed, and sitting in a chair, usually for the rest of the night.

PND results from the gradual redistribution of fluid, accumulated in the periphery (lower extremities) during the day, to the central compartment where the ensuing volume load exceeds the output capacity of the compromised myocardium raising the end diastolic pressure of the left ventricle. By contrast, in a variety of diseases breathing is made easier upright than supine (orthopnea) and the discomfort is felt immediately on lying down.

Another useful example of a highly specific finding includes mononeuritis multiplex. In distinction to the much more common polyneuritis, which has a myriad of causes, mononeuritis multiplex has a much narrower differential that includes collagen vascular disease (particularly, rheumatoid arthritis, polyarteritis nodosa, and the various vasculitic syndromes), diabetes mellitus, and cancer.

Pain

Pain is a frequent presenting complaint for many diseases. The history provides important diagnostic clues about the origin of pain.

Pain that is aggravated by movement, and that makes the patient lie still is characteristic of an inflammatory process.

The patient’s reaction to pain is more important than the subjective descriptions of the pain itself.

With an acute inflammatory abdominal process like cholecystitis or pancreatitis the patient lies absolutely still.

Colic, pain that waxes and wanes, indicates pressure changes in a hollow viscus such as the biliary system or ureter; it is brought on by obstruction, usually from a stone. The response to colicky pain is characterized by an inability to get comfortable and by writhing around or pacing the floor.

Maneuvers that accentuate or ameliorate the pain are also important to note.

Pleuritic chest pain, for example, is worsened by deep breathing or coughing, reflecting inflammation of the parietal pleura.

THE PHYSICAL EXAMINATION

To become expert at physical examination requires practice. Establishing the bounds of normality, and therefore the ability to elicit the abnormal finding when present, requires experience and attention to detail.

Although advanced imaging and other testing have unfortunately and inappropriately denigrated the value of physical examination (PE), it remains the cornerstone of clinical evaluation for the following reasons.

1. It is virtually harmless, distinguishing it from many other modes of evaluation.

2. Along with the history it guides all subsequent investigations.

3. It is neither feasible nor desirable to do widespread testing without a clinical evaluation first. When prior probability of a disease is low, false-positive tests abound.

4. It is useful for assessing progression of disease and response to treatment.

5. The “laying on of hands” strengthens the physician–patient relationship.

When encountering a new patient with an undiagnosed disease a full examination should be performed and all organ systems assessed even while concentrating on the area suggested by the history. A full examination includes noting and describing the attitude of the patient in bed and a careful recording of the vital signs. In addition to listening to the chest and palpating the abdomen, feeling for all pulses, testing strength in all major muscle groups, eliciting and recording all reflexes, assessing the cranial nerves, and (with some exceptions) a genital and rectal examination should be part of every physical.

In a patient with leg pain, for example, how will you be certain of an absent pedal pulse if you have not examined this in many patients without lower extremity vascular disease? In assessing the likelihood of increased intracranial pressure how will you identify papilledema if you have not examined many normal fundi and noted the presence (or absence) of venous pulsations?

LABORATORY TESTS

Never let a single laboratory result dissuade you from a diagnosis strongly suggested by the weight of the clinical findings.

Discordant laboratory results should be repeated.

Always start with the least specialized tests. A CBC is always indicated in the evaluation of a sick patient where the diagnosis is not known. The CBC contains a lot of information, much of which is frequently overlooked.

A WBC without a differential is not interpretable and therefore useless.

The percentage of polymorphonuclear leukocytes (granulocytes) and the presence of immature forms (bands), in comparison to the percentage of mononuclear cells (lymphocytes plus monocytes) are of particular importance.

The presence of eosinophils argues forcefully against bacterial infection.

In the absence of a documented pre-existing cause for eosinophilia the usual mediators of inflammation and the hormonal response to severe illness effectively clear the blood of eosinophils.

Toxic granulation, an outpouring of immature granulocytes with large granules and vacuoles, indicates infection.

An elevated platelet count is a very good marker of an inflammatory process.

An elevated sedimentation rate (ESR) is unlikely to be helpful except in cases of temporal arteritis or subacute thyroiditis, where very high values are the rule.

ESR may be normal in the face of significant inflammation and modest elevations are too nonspecific to be useful.

ESR may, however, be elevated in dysproteinemias where the paraprotein causes clumping of the red cells or rouleaux formation.

Examination of the blood smear, therefore, may provide useful clues to the diagnosis.

IMAGING

Usefulness of the Chest X-ray

Although modern imaging techniques and sophisticated computer software have revolutionized diagnosis (as described in specific situations throughout this book), it is surprising that the simple chest x-ray still provides much useful information.

Although much less frequently used now than in the past, the PA and lateral chest x-ray can provide much useful information. Portable AP films are much less helpful.

There is no substitute for personally reviewing the chest x-ray.

Specific cardiac chamber enlargement can be assessed from the lateral view.

The right ventricle comprises the anterior border of the cardiac silhouette in the lateral view. Normally, the right ventricle abuts the sternum one-third of the way up and on a very steep angle; with right ventricular hypertrophy the cardiac silhouette hits the sternum one-half way up, the retrosternal space is diminished, and the angle is no longer acute (one could stand on it without falling off!). The posterior border of the heart in the lateral view is made up of the left ventricle. With left ventricular hypertrophy the retrocardiac space is compromised and the angle formed with the inferior vena cava is diminished.

Calcification in the costochondral cartilage in the elderly is frequently associated with mitral annulus calcification, so the former should prompt a look for the latter.

This may be an important clue to the presence of significant mitral regurgitation.

In evaluating pneumonic infiltrates the presence or absence of air bronchograms and the effect of the infiltrate on lung volume provide significant information as to the underlying cause.

Air bronchograms without loss of volume indicate a pneumonic consolidation like pneumonia, a so-called alveolar infiltrate; volume loss implies bronchial obstruction.

Location of the abnormality is important: upper lobe infiltrates suggest tuberculosis (TB) or fungal infection. TB is located classically in the posterior segment of the upper lobe; fungal disease in the anterior segment. Bullae are typically located in the upper lobes; middle or lower lobe bullae suggest α1-antitrypsin deficiency.

The lateral view is also helpful in assessing hilar fullness; a dense shadow in the shape of a donut suggests hilar lymphadenopathy; pulmonary vessels appear much less dense.

When the left hemidiaphragm is higher than the right, the possibility of a subdiaphragmatic process (abscess, enlarged spleen, adrenal mass) should be considered.

The right hemidiaphragm is normally higher than the left because it sits on the liver below.

Inability to “take a deep breath” during a chest x-ray does not reflect an inadequate attempt by the patient.

There is usually an underlying cause such as pain (in the chest or abdomen), muscle weakness, or congestive heart failure. In the latter excess fluid in the lung parenchyma decreases compliance and restricts the ability to “take a deep breath.” It is a faux pearl that the diminished diaphragmatic excursion reflects “poor inspiratory effort.”

SOME WIDELY APPLICABLE CLINICAL APHORISMS

Occam’s Razor: The Law of Parsimony as Applied to Diagnosis

Patients frequently present with constellations of symptoms and signs that may appear unrelated; in general, the best diagnosis will encompass an explanation that accounts for all the findings.

Occam’s razor cuts best in younger patients. In the elderly, the coincidental occurrence of several diseases will often contribute to the clinical picture.

The experienced clinician will quickly identify the few crucial findings in a complicated case that must be explained by the diagnosis.

These will often lead to an appropriate differential and point to the correct diagnosis.

The final diagnosis must explain the chief complaint.

Therapeutics

You can’t make an asymptomatic patient feel better. (“Never shoot a singing bird.”)

Related old adages include: primum non nocere (firstly do no harm); less is frequently more in the elderly. Loeb’s first and second laws state the obvious: if a patient improves during a course of treatment, continue it; if a patient worsens under treatment, stop it. (Robert Loeb was a renowned professor of medicine at Columbia.) Loeb’s third law has been banned in the interests of professionalism (“never trust a surgeon”).

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