Medical Diagnosis through Semiotics

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Medical Diagnosis through Semiotics: Giving Meaning to the Sign 
John F. Burnum 
1 November 1993 | Volume 119 Issue 9 | Pages 939-943 
Physicians are engaged in incorporating quantitative methods for making clinical decisions into their practices. An acquaintance with semiotics, the doctrine of signs, may complement this project. A sign stands for something. We communicate indirectly through signs, and by interpreting what signs mean we make sense of our world and diagnose and understand our patients. Thus, through association and inference, we transform flowers into love, Othello into jealousy, and staring eyes into thyrotoxicosis. 
Characteristically in diagnosis, beginning with an unstable inference, we test and otherwise ask questions likely to produce signs that support (or discredit) our hypothesis. In a literary sense, we join with the author to clarify and rewrite the text; creative interpretation is the key. Diagnosis is concluded through narration, by the meaning that is revealed by telling the story of the patient. 
Diagnosis will succeed only to the extent that we respect the principles and caveats of sign interpretation. The sign is both the key to the unknown and the master impersonator. The sign and its meaning are usually not the same; meaning has to be inferred. Because interpretations are made subjectively, they are circumscribed by the experience and bias of the clinician. Moreover, the contexts in which the sign appears shape the meaning of the sign and may change it altogether. 
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A sign is something that stands symbolically to someone for something—typically for something else—as flags stand for nations, green for go, and language for whatever we want it to mean. By interpreting and giving meaning to signs, we make sense of the world around us [1-4] and, by the same token, diagnose and understand our patients. 
A burly, hard-working, "good ol' boy" is brought in by his wife to find out why he has no energy. In a manner contrasting poignantly with his swashbuckling beard, jeans, and reptile skin boots, he says in a subdued voice, "I can't make myself go; it seems like nothing don't satisfy me no more". Depression moves high on our list of possible diagnoses; the patient's bearing and feeling of anhedonia are common stand-for signs of this disorder. And thus, through association and inference, we translate chest pain into oxygen-starved heart muscle, x-ray shadows into asbestosis, and Koplic spots into measles. 
For all its power, sign interpretation is a surprisingly chancy process; some 20% or more of our clinical decisions are suspect [5-9]. As responsible professionals, we try to improve our credibility by integrating the exacting mathematical techniques of epidemiology and decision analysis into our practices [9, 10]. Becoming acquainted with semiotics, the doctrine of signs, might well serve to complement this enterprise. 
	Scope of the Sign 
Humankind has been advancing itself by interpreting and communicating with signs throughout its history, from the hauntingly modern symbolic drawings in the caves of Lascaux to modern electronic information systems. Physicians of the Hippocratic school were well acquainted with the usefulness of signs in diagnosis; a flushed face stood for fever. They were also aware of the potential hazards of sign interpretation. In the Iliad, Hector, vacillating between whether to give battle, misread and failed to heed the flight of an eagle as an omen of disaster and led his Trojan warriors into bloody defeat [4]. 
Signs are ubiquitous in human affairs. Language is the cardinal sign [11, 12], but whatever else stands for something and says something to us is also a sign [1, 2], from literary texts and advertising to a twinkle in the eye. A physician sitting down and touching the patient is a sign of caring. The Greek Revival architecture originally imposed on our government buildings by L'Enfant bespeaks of majesty, permanence, and the pride of a nation asserting itself. Scarves and ties are the dress of thought. As for tea leaves, tarot cards, and stars, the reader may decide. 
In thinking about the sign, we join hands with such illustrious sign devotees as Saint Augustine, William of Ockham (of razor fame), Hobbes, Locke, and in our times, in France, Ferdinand de Saussure, and in the United States, our patron saint of semiotics, Charles S. Peirce [1-3]. This is said to be the Information Age. For much longer, it has been the Era of the Sign. 
Medical Diagnosis from the Semiotic Perspective 
From the semiotic perspective, in diagnosis and relating to patients, we physicians are on the receiving end of communication and must assign meaning to signs. Medical signs include the patient, the history and physical examination, test results, and all relevant information. Diagnosis, however, precisely because it does depend on transforming one thing into another, can be hazardous; uncertainty is never far away. As some wag said when the crafty 19th-century Austrian statesman Metternich died, "Now just what could he have meant by that?" 
Semiotics warns us that if we are to minimize errors in interpretation, we must remember that medical signs are but symbolic, often ambiguous proxies of truth whose meaning, furthermore, is shaped by its contexts and whose interpretation lies at the mercy of inference and the experience and bias of the individual physician. A brief look at these determinants will help us fix them in our minds. 
	Elements of Medical Interpretation 
Signs and Inference 
In most of our patients, the sign and what it stands for differ, and we must take risks and infer what is wrong. We can only assume that a particular murmur spells mitral stenosis. We usually treat patients with pneumonia based on what is most likely, not on that which is known. Science and medicine progress on the wheels of inference, but inference cannot automatically be equated with fact [13, 14]. 
As much as we depend on them, sign messengers can be capricious and lead us astray. Black stools represent gastrointestinal bleeding but could be caused by the patient taking bismuth subsalicylate or iron or by having eaten turnip greens. Hairy tongue leukoplakia is almost always diagnostic of AIDS, but fatigue points in a hundred directions. Such is the power of symbols that a person can wear a white coat and pass for a physician without having been near a medical school. False signs may be introduced by laboratory or physician error—or by chance alone. One in 20 blood chemistry tests in normal patients may be labeled abnormal but are caused by the results falling outside "normal" distribution curves [15]. Abnormal tests may be caused by normal laboratory and physiologic phenomena; for example, hyponatremia from high lipids and hyperkalemia from high platelet or leukocyte counts [16]. Signs light the way but are to be held suspect; "a map is not the territory" [17]. 
Subjectivity 
No matter its strength as an indicator of illness, the sign does not speak; its meaning must be extracted by the physician. Giving meaning to clinical data is a subjective process made possible but at the same time circumscribed by the individual physician's knowledge and capabilities; chance favors only the mind that is prepared [18]. Unless we have the receptors for it in our brains, we are unlikely to notice the slight nod of a patient's head with every heartbeat and make the connection between this and possible coarctation of the aorta (or aortic insufficiency). Diagnoses usually do not pop up automatically but are obtained by pursuing a personal point of view [19]; we may overlook the murmur of aortic insufficiency unless we specifically listen for it. On the other hand, fixation on one possible interpretation may cause us to over-read a radiograph or electrocardiogram. Also, if a test result for a suspected disease is negative, we may be lead to abandon our postulate too soon [15]. Nevertheless, we cannot know that which we do not already know and are unlikely to find thatwhich we do not suspect. 
Personal Bias 
Our interpretations tend to be biased [15, 20] and may go astray because experience wills our perspective [19, 21]. Just as Moby Dick has different meanings to Ahab and Starbuck, so too may a patient's cough suggest asthma to an allergist and esophageal reflux to a gastroenterologist: To a carpenter everything tends to look like a nail. With the flush of excitement that comes when we think we know the meaning of the sign, we might well stop a moment to reflect on the advice of Francis Bacon: ".whatever (the) mind seizes and dwells upon with peculiar satisfaction is to be held in suspicion, and that so much the more care is to be taken in dealing with such questions to keep the understanding even and clear" [22]. Our interpretations are by nature subjective and prejudicial, objectivity the goal. 
Contexts 
As in all forms of symbolic communication, the medical sign is not an autonomous messenger; the meaning that we construe must conform with its contexts [21, 23-25]. Diarrhea in an elderly bedridden patient spells (among other possibilities) fecal impaction, in a healthy youngster, the "summer complaint," a benign, unspecified transitory gastroenteritis. Ventricular premature beats have a grave import in patients with congestive heart failure but rarely so in the healthy. A low cholesterol level is a good sign, but not if the patient is malnourished—it all depends. Facts presented in a void are devoid of meaning. To ignore context is to invite misunderstanding and chaos in diagnosis and all forms of interpretation. 
Once named, a disease (disorder or condition) becomes a sign. The physician and patient must now join hands to interpret and comprehend the disease—to tell the story as it were—in terms of how it is expressed in and experienced by the patient [26]. The same pneumonias are not the same; the patient may be immunosuppressed. My headache is not your headache. A minor hangnail could have been a devastating consequence for a concert pianist. Understanding must be expanded to account for the circumstances surrounding the patient: family and employer sentiments, third-party regulations, societal and ethical restraints and other—often conflicting—contingencies [27]. In the end, many, many contexts have converged to bring greater and greater specificity and particularity of meaning to our interpretation. Contexts serve to reduce the ambiguity of the sign [24] and crystallize diagnosis. 
	The Interpretive Process 
I have been talking about the elements of interpretation and now the process itself. At times in medical care no interpretation is necessary. A splinter under the nail and scoliosis of the spine speak for themselves; in terms of disease alone, sign and meaning coincide. In some instances we derive meaning by following "if-it's-this-it's-that" rules or algorithms, or by assessing a datum (sign) as it relates to other data within a physiologic framework—as in working through fluid and electrolyte problems. The latter are two traditional types of diagnostic reasoning as described by Kassirer [28]; the semiotic equivalent of the third type, probabilistic reasoning, follows. 
More often we proximate meaning; rather than certitude, we deal with what is most likely [28-30]. Inferring from the signs what might be wrong, we test for truth and discriminate among competing diagnostic possibilities by examining for the presence of a mosaic of harmonious signs that we might expect to find if our conjecture (or one of them) was tenable. In the patient whose head nods with each heartbeat, we selectively inquire of the presence of leg cramps with exertion and look for a rib notching on the chest film and a delayed weak femoral pulse as further supporting signs of coarctation of the aorta, as opposed to aortic insufficiency. The more supporting signs that we can amass, the greater the particularity of description [31] and the less uncertain we are of that which is being portrayed. 
The corroborative signs are mustered selectively through communication and informed participatory interpretation, by the physician conducting a pointed, exploratory question-and-answer conversation with the patient and other sign sources. After selectively questioning the patient and suspecting angina pectoris, we elect to do a graded exercise test. In choosing this particular test, we are asking a leading question: Do the ST segments of the electrocardiogram become depressed with exercise and, if so, to what degree? The test results—the ST changes—is a yes or no, loud or soft answer to our question and a supporting or detracting sign. In a literary sense, we have narrowed the gap of uncertainty between writer and reader [32] by teaming up with the patient and other sign authors to rewrite and clarify the text; we have become both the creator of the information as well as its interpreter. 
	Quantifying Medical Decisions 
Turning for a moment to medicine proper, clinical epidemiology, decision analysis, and evidence-based medicine have provided quantitative methods to guide us in the retrieval and critical appraisal and use of medical information in making clinical decisions [15, 16, 33-39]. These advances constitute some of the most important additions to the medical canon of the last quarter century. 
Touching but lightly on some of these developments, the numeric diagnostic strength of an ever-increasing number of signs is now available [16] and is expressed as the sign's sensitivity and specificity and likelihood ratio, the latter being the odds that a given sign would occur (or be absent) in a patient with, as opposed to a patient without, the target disorder. If we are 50% sure in our minds that our patient with chest pain has coronary disease and the likelihood ratio of the electrocardiographic changes occurring on the graded exercise test is 10, we can read off a simple nomogram that the probability of disease has been increased to 90%; our interpretation has been numerically authenticated. 
Semiotics emphasizes that the sign must be interpreted in terms of its contexts; Bayes theorem that the likelihood of a test correctly predicting the presence or absence of disease depends not merely on the strength of the test but on the likelihood of the patient having the condition in the first place. Both are making the same point; the before-test likelihood of disease (prevalence) is a numeric expression of the effects of risk factors and other contexts. Even though two patients have similar chest pains as presenting signs, positive electrocardiographic changes on a graded exercise test would be far more likely to indicate coronary disease in an overweight hypertensive 60-year-old male cigarette smoker than in a 24-year-old female jogger with mitral valve prolapse. The contexts of the sign and, therefore, the probability of disease differ [40]. 
Decision Analysis 
The interpretation of a sign is usually followed by some appropriate action [41], which in medicine translates into doing what is best for the patient. Just what is best, however, may be difficult to say. We would have no problem recommending hip replacement for a degenerated hip to an otherwise vigorously healthy star athlete. Surgery would likely be successful and, if so, of immense value to the patient. On the other hand, in a 70-year-old sedentary accountant with a history of a previous pulmonary embolus after an automobile accident and with increasing symptoms of prostatism, determining whether it would be best to operate would be far from clear. Using decision analysis, the most propitious course of action can be determined by weighing and comparing consequences; the act with the most highly valued outcome is the winner. The values of the differing outcomes are derived by multiplying the probabilities of the outcomes taking place by their assigned numeric utilities or net benefits (relative preference) for the patient [42]. We can also establish ascending threshold levels of probability of disease at which,moving up in ascending order, we would be advised to stop and observe, test, or treat the patient [43]. Just as I discussed in diagnosis, we must eventually incorporate the concerns of patients, society, and other contexts into our final management decisions. 
	Discussion 
The care of the patient turns on diagnosis and understanding, and these we attain by wresting meaning from signs, from anything sensed or perceived concerning the patient. Diagnosis begins with having an ear for language, with semantics, that part of semiotics that has to do with the meaning of words and phrases. Words are but arbitrary sounds standing for what is meant, and we must know the vernacular as well as the scientific tongue if we are to understand our patients. When the granddaughter says that grandpa is stubborn, she may mean that he is constipated, not obstinate. In a person with shortness of breath, the phrase, "the air won't go down far enough" or "doesn't do me any good" denotes hyperventilation and anxiety as opposed to congestive heart failure and other causes of dyspnea. 
Communication is not limited to the spoken word. If our good ol' boy had said nothing, his manner would have screamed depression; Sherlock Holmes diagnosed his case when the dog did not bark. Medical education imparts to us a specialized vocabulary of signs and how to interpret them. We must know the caprice as well as the dependability of signs. We can count on Kayser-Fleischer rings meaning Wilson disease, but a patient's apparent cyanosis can be caused by having used silver-containing nose drops as a child, and one can be blue at the beginning of a chill but be in no need of oxygen therapy. A person carrying a stethoscope does not have to be a doctor; one can smile and still be a villain. 
The sign alone is not the agent of meaning; the answer to a diagnostic puzzle often lies in its contexts. Overbreathing in an otherwise healthy college student spells anxiety; in an obese elderly postoperative patient, a pulmonary embolus; or bacteremia if a catheter has just been changed. Our diagnostic abilities are as good as, but no better than, our experience; we never heard the click of mitral valve prolapse until we heard about the condition. But even the most prodigious sign vocabulary cannot prevail against sloppy work and bias. Oh, how easy it is while hurrying through rounds in the nursing home to miss the slightly turned-out foot of the silent broken hip, or, in our preoccupation with the lungs, to overlook mitral stenosis in a patient with hemoptysis. 
References to semiotics appear infrequently in the medical literature and usually in relation to psychiatry. Some psychotic patients cannot distinguish between the sign and that which it signifies [44]. Some emotional disorders may arise from distorted stereotyped misinterpretation of signs. An innocent casual remark from another person may be interpreted as if it were coming from the dominating mother of the patient's childhood. Panic attacks may be detonated by harmless palpitations being mistakenly perceived as a harbinger of an impending heart attack. 
The word "semiotics" appears more frequently in European medicine and usually in the sense of a manifestation or sign of a condition, such as the radiographic semiotics or the echocardiographic semiotics of a certain disorder [45]. What I have said about sign interpretation as a primary activity of the clinician applies with equal cogency to understanding legal matters and interpreting literary and ancient religious texts [46-48]. Nietzche may have been close to the truth when he asserted that there are no facts, only interpretation [49]. Epistemology, hermeneutics, phenomenology, linguistics, and information theory all bear on questions of interpretation and knowing. In deconstruction and other branches of literary and art criticism, the debate goes on; for example, whether there can be any one agreed upon meaning of a literary work or painting [4]. 
Some diagnoses are obvious at a glance while others follow automatically from fixed rules and binding physiologic relationships. For the most part, we make a series of inferences of what is wrong until we arrive at a reasonably secure point for action [50]. In semiotic language, we set out to reduce uncertainty by conducting an exploratory conversation with the patient and other sign sources through which we selectively probe and uncover signs that we might expect to be present if our postulate was true or be absent if it were not. Suspecting a kidney stone in a patient with excruciating back pain, we ask if the patient paces about in an effort to relieve the pain; suspecting thyrotoxicosis in a listless elderly patient with atrial fibrillation, we order a thyroid profile. To choose a test or look up a point in the literature is to ask a discriminating question and the test results in an answer—and a sign; creative interpretation is the key. In literary terms we join the patient, the laboratory, and other sign authors to clarify and rewrite the text; reader and writer become one. 
We always prefer to go beyond the logic of sign reasoning and make the reliability of our decision mathematically explicit, but in the hurly-burly of practice, this is not always possible or necessary. Whatever the case, to arrive at a codable medical diagnosis in our quest for meaning is only halfway home. As with lawyer and client, we are involved in telling the patient's story. "The story is the most basic way we have of organizing our experience and claiming meaning for it" [51]. At the same time other stories must be given their say, what the situation means to the family, society, ethicists, insurance companies, and others. 
The sign is the badge and mover of civilization—without signs nothing is conceivable [3]—but its use entails certain risks that must be heeded if we are to "keep the understanding even and clear" [22]. The meaning that we give the sign is inferred and thus haunted by uncertainty. In their ambiguity medical signs may lead us down several trails, and we must often think in terms of what is most likely rather than in absolutes. Because interpretation is subjective, it is subject to bias and to the constraints of personal experience. Finally, the contexts in which the sign appears shape the meaning of the sign and in some cases may change it altogether. 
The emphasis on sound clinical reasoning and the grafting of the quantification methods of clinical epidemiology and decision theory into medical thought has dramatically increased the quality of medical research and journal reports and promises to go far in improving the accuracy and appropriateness of the clinician's diagnoses and management choices. At the same time, in a complementary fashion, some knowledge of semiotics stands to further our cause: "Man's achievements rest upon the use of symbols (signs)" [52], as does much of our understanding and care of the patient. 
	Author and Article Information 
Requests for Reprints: John F. Burnum, MD, 400-C Paul Bryant Drive, East, Tuscaloosa, AL 35401. 
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