Diagnosis

DIAGNOSIS, DIAGNOSTICS (from Greek diagnosis-recognizing). The term diagnostics encompasses all those actions and reasoning by which the individual picture of a disease is reduced to diseases and peculiarities of the organism known to science at a given time; the term diagnosis, however, denotes the name given to a disease in a specific particular case. History of diagnostics. The beginning of D. goes back to the depths of centuries, as generally does the beginning of medicine and any culture. D., like the history of medicine as a whole, reflects not only the main stages of cultural and socio-economic development of humanity, but also all the details of this growth. Moreover, it is precisely socio-economic factors that explain the state and progress of D.: for example, the appearance of plague in Western Europe in the 14th century gave rise to extensive study (and recognition) of this disease and spurred the development of the question of infectious diseases - the number of types of infectious diseases, which had previously been counted as 5, grew to 8, and soon to 11-13. In particular, the development of technology as a significant lever and indicator of progress armed D. with new methods of recognizing disease (for example, mirrors in gynecology, ophthalmology, etc., X-ray fluoroscopy); the perfection of diagnostic instruments (for example, the gynecological chair) corresponded to the level of technology. The connection between medicine, resp. D., and technology is not expressed by simple and casual service of the first by the second; this connection is fundamental: thus, the works of Pasteur, caused by the needs of the chemical industry, were immediately transferred to medicine and received exceptional importance for D. The history of D. could be divided into periods according to the level of development and application of technology in it. However, it is not this, but the class structure of society that imposes characteristic features on medicine, resp. D.; as long as society had not gone beyond the framework of primitive communism, medicine, resp. D., was the property of all: for example, among the ancient Assyrians there was a custom of bringing patients out onto the road and allowing passersby to "examine" the patient, giving advice. Complicating conditions force D. to transform into a more skillful, developed state. Philosophical schools, successes of exact sciences, the state of general medical disciplines (anatomy, physiology, pathology), medical schools as moments playing in relation to D. the role of prerequisites, have important significance in the development of D., however only special, since their own state is determined by the same circumstances mentioned above. Their insufficient development allowed for long wandering around questions about the essence of disease and classification of diseases, which had a harmful effect on the development of questions of D.: explanation of the causes of disease was assumed either in the settlement of a spirit in the body, or in its corrupted juices, etc., or disease was given the significance of a local process. As the basic diagnostic method, intuition, based on observation and experience, is put forward (especially since the time of Hippocrates); diagnosis for a long time retained individualistic traits - experiment, laboratory, technology gradually conquered their place in diagnostics, with the general progress. At the same time, for a long time the attention of medicine was diverted to treatment and prognosis; not what causes the disease was interesting, but what eliminates it - said the Roman empiricists. Thus, diagnostics grew gradually. - Its first stage, the stage of primitive medicine, in its initial, empirical stage descends to prehistoric life, when at the basis of the physician's thought (and action) lies a primitive reflex act, in essence close to similar manifestations in higher animals, for example, a monkey extracting a splinter with its hand. But the experience of one generation was passed on to another - empirically primitive medicine was created. The more obvious and frequently a disease occurred, the better it was recognized; but this was reduced (except for visible wounds and fractures) to establishing little and mainly what now in the overwhelming majority of cases constitutes only symptoms of disease - vomiting, diarrhea, fever. Subjectively - pain, objectively - the above-mentioned signs determined the disease, and the method of diagnosis was visibility. In other words, the primitive character of primitive medicine corresponded to the primitiveness of D.-With the transition to patriarchal society, when the division of social labor begins, when priests are singled out, concentrating in themselves experience and knowledge (including medicine), and natural phenomena (not excluding health and disease) find explanation in the action of supernatural forces - spirits (demons), - a demonic "theory" of explaining diseases arises. It is clear that at this stage of social development medicine and all the more D. do not stand high; moreover - religion hinders the development of medicine as a whole and D.-True, along with demonism empiricism is also preserved, which at the highest stage of patriarchal society often steps forward significantly; thus, Indians knew fever - burning "suddenly" or "with slow fire", "cold" and "burning", returning daily, the next day or on the third. Accordingly D also rose. Thus, among Egyptians inspection, palpation and auscultation were already applied; inspection of the form of the body, its color and the position of organs was used; the abdomen was palpated in relation to consistency; attention was for the first time paid to body temperature. "Make the patient lie down", "you will find that under your fingers with the hand in a calm position there occurs a vibratory movement", "the ear will hear here" - such are the remarks of papyri. In temples books of the god Thoth were stored, of which the sixth contained semiotics and D. Later in Greece two most remarkable schools - the Knidian (Euryphon, Ctesius) and the Cossack (Hippocrates) opened a new era in medicine, for which the ground was prepared in the form of knowledge accumulated over centuries, which remained to be united, synthesized. In the field of D. Hippocrates (see) deserves attention. The symptoms of disease in Hippocrates are presented more clearly, often more vividly than in his predecessors; for example, the description of marsh cachexia is given as follows: "Always huge, hard spleen, abdomen drawn in, lean and hot, their shoulders and collarbones protrude, devoid of flesh. Their body melts away due to the spleen. They are constantly hungry, suffer from strong thirst, are prone to frequent and dangerous dropsies, diarrhea and dysentery; they also suffer from prolonged 4-day fevers, ending in dropsy or death". The description of apoplexy is even better: "Sanura derepenite invadit dolor circa caput; et statim vox intercipitur, et stertit et os hiat; si quis ipsum vocet aut moveat solura suspirat: nihil autem intellegit et multum mingit et mingere se non sentit" ("A healthy person suddenly feels headache; he immediately loses the power of speech, snores, and the mouth remains open; and if he is called or pushed, he only groans; at the same time he lacks consciousness, he passes much urine, but does not feel it himself"). For diagnosing the disease Hippocrates used inspection, palpation and auscultation: "Judgments are made by means of eyes, ears, nose, hands and other known methods to us, i.e. by sight, touch, hearing, smell and taste". He recommends beginning the examination with the face, paying attention to its redness, tearfulness of the eyes, fear of light, color of the apple of the eye, pupils, color and smell of the tongue; he pays attention to the forms and position of organs, to the rigidity of the neck, swallowing, frequency of breathing, state of perspiration, pulsation of arteries, especially - temporal. Hippocrates also developed auscultation of respiratory organs: he knew tracheal rales, fine-bubble moist ("Applying the ear to the side of the patient and auscultating it for a longer or shorter time, we hear inside as if boiling of vinegar"), noise of pleural friction, compared by him to the crunching of a leather strap. He did not neglect body temperature either, determined by applied cold clay: "Ubi in corpus sudor est, illic morbum esse declarat. Et ubi in corpore frigiditas aut caliditas est, hie morbus est" ("Where there is sweat in the body, this reveals disease; where in the body there is cold or heat, there is disease"). For determining exudative pleurisy he used shaking of the patient. He also practiced questioning of the patient; for example, he says that to determine the beginning of suppuration one must ask about the day when the patient felt chill. When examining the patient Hippocrates at the same time tried to make a prognosis, which is evident for example from the following: "In pneumonia, rusty sputum mixed with a small amount of blood is salutary and brings great relief at the beginning of the disease; but if it appears on the seventh day, then this is a less reliable sign". Hippocrates also attached importance to the external appearance of secretions; by smell, taste and other signs he recommended determining the property of urine, sputum and blood. He also used some instruments for examination, for example for studying the uterus - a probe (speculum). The later Alexandrian school also has its merits in history: the anatomist Herophilus became famous for his research on the pulse (fullness, frequency, strength, rhythm), the significance of which for D. was already taken into account by Hippocrates. Herophilus proved the connection of the pulse with the work of the heart and applied water clocks to study the question.

Next, the school of empiricists (Phyllinus of Cos, Serapion of Alexandria-II century, Heraclides), which dealt with the study of individual questions, based its observations on its own, others' conclusions by analogy, which allowed for the improvement of the study of symptomatology and diagnosis of diseases. In Roman medicine, three schools struggled against each other- the empirical, the dogmatic, and the methodical. The representative of the dogmatists, Soranus, who finally linked Greek and Roman medicine and brought it to the height to which it later did not reach in Rome, brilliantly described the signs of diseases, distinguishing them from symptoms (more varied and less constant) and dividing them into subjective (weakness, fatigue, thirst, dizziness) and objective (appearance of the patient, pulse, breathing). He is credited with the foundation of differential diagnosis. He practiced inspection and palpation and was the first to introduce (later forgotten) percussion, noting the tympanic sound (in application to the abdomen). He developed auscultation in detail (distinguishing by ear noises in the abdomen, chest, rumbling in the intestines, resonant and scraping noises in pleurisy, hissing in pneumonia). He also paid attention to body temperature, and described the examination of the pulse in detail; with the help of touching with objects, he also examined sensitivity. Soranus particularly improved the examination of sputum and urine, describing abnormal impurities in them-blood, pus, sand deposits, fatty substances. In the field of gynecology, he invented a chair for examining female patients.-After Soranus, individual schools and doctors contributed to the development of diagnosis with clarification and individual points; thus, Archigenes developed the doctrine of the pulse, Antimus-indications for surgical operations, Aretheus deepened the description of a number of diseases (his work 'On the causes and signs of acute and chronic diseases' masterfully presents the question) and was the first to be able to auscultate the heart. Among the eclectics, Galen (see) united and synthesized, like Hippocrates, all the experience and knowledge of ancient medicine as a whole, bringing it to its culmination point; after him, doctors split into specialties to accumulate experience anew, and for a long time were influenced by both Hippocrates and Galen. Just like his predecessors, Galen placed more emphasis on prognosis and treatment than on diagnosis. Nevertheless, he also merits in diagnosis. Thus, Galen diagnosed fever mainly on the basis of heat and pulse, which he described in detail, dividing it into numerous kinds.-After Galen, medicine stagnated; this period (II-VIII centuries) was the end of the declining Roman Empire. Creative thought was more replaced by translations and compilations; encyclopedism was emerging, superstitions and incantations were developing; such was especially the medicine of Byzantium. Indeed, there were bright spots against this background-Oribasius (IV century), who wrote a compilation in 70 books, Aetius, who left a vivid picture of medicine in the 6th century (made the first attempts to describe the localization of brain diseases), Alexander, who wrote '12 medical books', Actuarius (XI century), who attached great diagnostic importance to the study of urine, which he collected in stacks, and distinguished in it the sediment, its less dense part, and the cloud.-Having adopted and preserved Greek medicine, the Arabs (Aaron, Avicenna), using the experience of existing medical institutions (hospitals for slaves, troops, Christian infirmaries), developed diagnosis, introducing many new elements. Avicenna's compilative guide-'The Canon of Medical Art'-has not lost its significance in the East to this day; in addition, he carefully described leprosy, which he named for the first time lepra. XI-XV centuries constituted a new era. The Salernian school and the school of Montpellier created nothing noteworthy in diagnosis. Even less so could the schools that arose somewhat later in Bologna, Padua, and Paris do so: the dominance of scholasticism, characterized by detachment from life, one-sidedness, dependence on theology, and the influence of Aristotle under the guise of serfdom feudalism, veiled by the church, stifled all living things.-At the end of the XV century and at the beginning of the XVI century, the era of the Renaissance began, which developed into the Reformation: authors appeared, for example, Ramus, who opposed scholasticism and sought new methods in clinical practice. The Reformation in medicine was begun by Paracelsus (XVI century), who proved the inadequacy of the traditional four humors; his merits include the doctrine of metabolism, syphilis, and in diagnosis-of experiment. Nevertheless, his inability to give anything clear led him himself to mysticism, metaphysics, and subjectivism. The XVII century was more productive: advances in anatomy and physiology could not but influence subsequent achievements in diagnosis, as well as the mechanistic doctrine of Descartes (XVII century), which had a great influence on medicine. At the same time, discoveries in the field of chemistry and physics created two schools-iatrochemists and iatrophysicists; the former put forward the doctrine of the ferment (Helmont), returning to the humoral theory, while the iatrophysicists, reducing everything to mechanics, developed physical research methods; thus, Santorio Santorio used scales, a hygrometer, and other instrumental methods; Delebe began clinical education by teaching diagnosis at the patient's bedside.-The XVIII century continued the movement of the previous century: the influence of Leibniz and Wolff helped to expel mysticism from medicine and begin to apply physics, mathematics, and microscopy in it: this was all the more important since there were still attempts, for example, in Stahl (animist), to explain everything by 'life force'. However, Bordeu, trying to subordinate theory to practice, applied the thermometer and the magnifying glass for the first time, proposed a classification of diseases; for diagnosis he demanded the application of analogy and observation. The Vienna school (XVIII century) introduced many new elements in diagnosis: one of its pupils-Auenbrugger discovered percussion in 1761, which, however, spread only thanks to Corvisar; this led to the development of auscultation. However, the final restoration of the forgotten auscultation belongs to Laennec (1819), who invented the stethoscope. But in the XVIII century, a return to vitalistic views is also noted: Bordes became a harbinger of new vitalism, Barté substantiated the 'vital' principle. The German school, in the person of Ralle, also put forward a speculative 'life force'; Mesmer, using natural philosophy, put forward the concept of fluid. Nevertheless, diagnosis also had its merits here; for example, Barté's merit is his analytical research method.-But the vigorous development of medicine and diagnosis belongs to the XIX and XX centuries. From the beginning of the XIX century, clinical and laboratory directions arose in medicine. In 1806, Corvisar's first major work on semiotics appeared. Laennec could now approach the development of diagnostic issues more closely, particularly auscultation. With its help, he established a number of symptoms of diseases (cavities, metallic tone, crepitant rales), dividing them into types. Laennec also described new diseases, for example, cirrhosis of the liver. The development of medicine moved forward quickly; new descriptions of diseases appeared (for example, Rouset determined apoplexy from hemorrhage, Bouillaud-disease of the endocardium). New discoveries in theoretical medicine were also of great importance: Schwann (1810-82) discovered the animal cell, Meyer had already founded histology; Virchow (see) created cellular pathology, Claude Bernard (see), founder of the latest experimental method, who discovered the function of the pancreas, glycogen, etc., played a major role for diagnosis. Other successes of diagnosis also belong to this time: for example, Frank proved the presence of sugar in urine, Addison discovered a disease that received his name. Finally, venereal diseases (syphilis and its manifestations) were fully studied, and new classifications were proposed for skin diseases (the foundation of new dermatology-Hebra, 1841); in the field of neurology (which had separated into an independent discipline since Charcot's time), myelitis, neuralgias, neuritis, progressive muscular atrophy, etc., were studied in more detail, as well as mental diseases; kidney and liver diseases were also studied in more detail; descriptions of new diseases appeared (stomach ulcer, anemia). All these discoveries are connected with new data in the fields of anatomy, pathology, and physiology (see Internal Diseases). Accordingly, diagnosis was enriched with new methods of recognizing diseases and their signs; in particular, Pirori invented the plessimeter (1826), Wintrich-the percussion hammer, Marey-the sphygmograph, Recamier-mirrors for uterine examinations, Desorme-the endoscope, Türck and Czermak-the laryngoscope, Helmholtz-the ophthalmoscope. With the help of a microscope, the formed elements of blood began to be recognized and their quantity counted; examinations of protein and sugar in urine, etc., also began to be performed. The number of pulse beats and respiratory movements began to be counted; the thermometer became a necessary accessory for diagnosis in the clinic. Thus, to physical methods, instrumental methods were added. However, the modern flourishing of diagnosis begins only after 1870: medicine owes this to Pasteur, who discovered microorganisms, after which a series of bacteriological discoveries began. In connection with this, the doctrine of immunity (see) and its application to diagnosis (Wasserman reaction, Widal reaction, Pirquet reaction) were developed. X-ray fluoroscopy and radiography were used for the diagnosis of diseases. Microscopic examination of blood, gastric juice, sputum, urine, and feces received full development. Instrumental research methods improved and new ones were created, for example, endoscopy.

For diagnostic purposes, recourse is had to special methods, for example, research into blood pressure or research into reflexes (for example, Westphal's, Babinski's). D. also serves graphic methods (see). D. is established on the basis of taking into account the work and functions of individual organs (for example, glands). In short, D. is armed not only by questioning, observation, exact knowledge of the signs of diseases, not only by physical and instrumental examination, but also by laboratory, bacteriological, operative methods, subordinating to the tasks of diagnosis all medical knowledge as a whole, utilizing technique and experiment; not only intuition helps to sort out the disease, all the data obtained from all methods and techniques of research, but also systematic thinking, applying for analysis and synthesis inductive and deductive methods. In connection with the successes of diagnostic research methods, new symptoms are discovered, new nosological units are isolated, and corresponding classifications of diseases are created. In other words, D. of diseases bears the imprint of the prevailing general pathological views of each epoch (organopathology or humoralism, anatomical or functional substrate). Russian medicine, resp. D., does not deviate in its development from subordination to the general laws of the development of medicine, passing through all stages of the socio-economic development of the Russian people and repeating what had to be passed through by the general history of medicine. In particular, Russian medicine goes from deep antiquity, being connected in the times of Kievan Rus' and the Moscow period with the monastery and the church. Already in the 10th-12th centuries, many diseases were known to it, for example, such as tabes, tumors of the lymphatic glands. The development of truly scientific medicine begins in the early 19th century with surgery, as called forth by the needs of the then statehood, conducting military campaigns (see Surgery); however, the brilliant period of Russian surgery begins with Pirogov, who founded experimental medicine and left many treatises that anticipated in the field of anatomy and surgery even the achievements of Europe. Internal diseases did not stand high until the middle of the 19th century; in it the views of Brown and Broussais predominated. All these circumstances determine the state of D. for the same period.-On the heels of Pirogov came outstanding surgeons-Gruber, Bobrov, Pavlov, Dyakonov, Skliossovsky, Vyiaminov; famous pediatricians appear-Rauhfus and Filatov, gynecologist Snegirev, psychiatrist Korsakov, who left works which retain enormous value for D. to this day. If the state of internal medicine until this time is characterized by the fact that Toporkov considered percussion and auscultation to be quackery, then the appearance of Botkin, Zakhar'in, and Ostroumov (see) lays the foundation of Russian medical schools. Zakhar'in, a 'Hippocratist,' empiric, attached great importance to the anamnesis, bringing it to an unprecedented height, providing the physician with an 'individual' picture of the disease; observation at the bedside of the patient was his basic method of recognizing the disease; he demanded individualization in the evaluation of the disease, the ability to correlate the observed symptoms with the specific condition of the organism. Botkin puts individualization at the head of his practice and advances the study not of the disease, but of the patient; however, he bases this study on a scientific basis: patho-anatomical changes, etiological and pathogenetic moments he correlates in establishing the diagnosis; stating for example that changes in the function of the heart do not always coincide with the patho-anatomical picture, he put forward functional D.; he is the one who described the postsystolic murmur in narrowing of the mitral orifice; he also developed the question of the significance of the wandering kidney in pathology, of the infectious origin of catarrhal jaundice, of the role of the breakdown of protein bodies of the blood in fever, etc.; in accordance with this he introduces laboratory methods. Ostroumov, close to Botkin, proceeding from the fact that the disease in different individuals can manifest differently depending on the constitution of the patient, etc., deepened D. in this direction and in particular-the collection of the anamnesis. Other authors advanced D. further: Dashkevich with his doctrine of fever, Stol'nikov with his method of determining protein in the urine, Obraztsov with his methodical palpation, Mechnikov with his doctrine of inflammation, phagocytosis, the role of a number of microbes, etc. Finally Sechenov with his development of the question of the reflexes of the brain, of the gases of the blood, of the coefficient of absorption of CO₂, the works of Pavlov on digestion and conditioned reflexes, Kravkov on pharmacodynamics, as well as their students and scientists of recent times in all fields of medicine and related knowledge, in particular in the field of bacteriology, endocrinology, genetics, etc., open brilliant perspectives for D., which already now in the USSR stands at the level of world knowledge, based on biological data, on the broad study of diseases in medical institutes and armed with instrumental and other methods for recognizing diseases. This is especially favored by the general conditions and direction of Soviet medicine and scientific research work in the USSR, where collective methods of work and materialistic world-view (see Dialectical materialism and medicine) contribute to the successful development of diagnostics.

A. Shchegolkov - Essence and methods of diagnosis. The data on which a diagnosis is based are extremely diverse. They include the patient's complaints, indications from those around them, data on heredity, living conditions, in general the anamnesis of the given disease (anamnesis morbi), life anamnesis (anamnesis vitae), objective examination, and everything that is learned through communication with the patient. The study of the obtained data reveals a number of objective or subjective peculiarities and deviations, which are known under the name of symptoms and form the basis of our clinical, applied concept of disease. From the symptoms observed at the moment of examination is formed what is called in diagnosis status praesens. Adding to status praesens the history of the development and origin of symptoms, as well as those symptoms that were present but then disappeared and are known only from the anamnesis, one obtains what is called the picture of the disease, which characterizes the given disease more fully than status praesens alone. The centuries-old experience of observing patients has shown that symptoms repeat and that certain of them often occur together, develop in the same sequence, end similarly, and lead to similar results. From such frequently occurring characteristic symptom complexes is created the clinical concept, the concept of a certain disease. When approaching diagnosis, the physician has at his disposal the picture of the disease of the given case, and in addition he is armed, on the basis of his study and experience, with knowledge of a large number of symptoms and diseases. Encountering some symptom or combination of them and recalling in which diseases this sign (or their combination) he has encountered or described by others (as far as he knows), he builds a hypothesis about the existence of such-and-such a disease in this case. Having assumed the existence of one disease A or another, which possesses a number of symptoms (a, b, c...), he compares his assumption with reality, and if it turns out that besides a, there are no other symptoms common to the disease he assumes and this case, but there are others in this case which are not characteristic of the disease he assumes, then the hypothesis has to be considered refuted, and instead of disease A, another disease B with symptoms a', b', c' etc. should be assumed. This entire process of comparison, due to frequent repetition, occurs the faster the more experienced the physician, and in the mind is replaced by the concepts of similarity-dissimilarity. Such a diagnosis succeeds easily and simply if recognition is based on a sufficient number of characteristic symptoms. Methodical comparison is an operation very frequent in descriptive sciences. The botanist and zoologist, in determining a plant or animal, and the physician in diagnosing a disease are in a similar situation; however, the physician's position is many times more difficult: clinical symptoms are more complex than the data of descriptive sciences already because in them function and time play a large role. The complexity of the picture of disease would not be an insurmountable difficulty for D.-classification by symptoms if there were not still one more fundamental obstacle. Every classification is based on the existence of constant signs, whereas the clinical picture of diseases is poor in constant signs and varies more than the species of animals and plants. In textbooks, the description of every disease is invariably accompanied by an indication of the possibility of great diversity in it. Individual symptoms sometimes drop out completely, others may change to the point of being unrecognizable (polymorphism of symptom). The coincidence of symptoms existing in 'pure', uncomplicated cases ceases with the appearance of any complications, and when the general similarity is lost, a diagnosis cannot be made. Moreover, many diseases, at least during one or another period of their development, give no symptoms—neither objective nor subjective. This is explained by the fact that there are many signs of diseases that are inaccessible to clinical observation, and are accessible only to pathological, histological, etc. research. However, the botanist and zoologist can dissect their objects, while the physician, dealing with a sick human being, is limited in his methods of research and observation. Consequently, the physician must recognize diseases on the basis not of all their inherent signs, but only of certain ones, namely those accessible to clinical observation, i.e. symptoms. Thanks to this, diagnosis would rarely be possible if, in the study of diseases and symptoms, besides the descriptive, the explanatory method of study were not also applied. Detailed acquaintance with many pictures of diseases shows that the appearance of recurring symptoms and symptom complexes is not accidental; more comprehensive (not only clinical) research has shown that the signs of disease can be clearly connected with each other. Between individual symptoms there sometimes exists a dependence, and it can be so obvious that no special knowledge is required for its understanding (pain-insomnia-exhaustion or improper configuration of the lower extremity and lameness). But especially important is the connection of symptoms—obvious clinical signs—with signs inaccessible to clinical observation, hidden but necessary for the characterization of the disease. Neither anatomy nor physiology is sufficient for clarifying the connection of disease signs with each other. They give a concept of the organism, at every step regulate the course of diagnostic thought, and help in the examination of the patient, but they do not pay special attention to the question of what anatomical-physiological regularities in the living conditions are most often disturbed and what new phenomena (including symptoms) arise in this case. The individual organ and individual function do not stand in the organism in isolation, but through the nervous system and humorally are connected with others. Therefore, when the function or integrity of any organ changes, other organs are also drawn into the pathophysiological picture, and the result is very complex, and one can only approximately predict what symptoms will result from this. Thus, it is not always possible to mentally construct a symptom as a conclusion from the data of normal anatomy and physiology; only clinic, autopsy, and experiment bring clarity into this field. Thanks to all these studies, many symptoms receive a visual explanation. One always seeks the connection of a symptom with other signs, and the very concept of a symptom becomes complete if it is accompanied by some explanation of its appearance or origin. Most symptoms are connected with a definite organ or definite function (jaundice, excretion of large amounts of protein in urine, coughing up sputum, enlargement of the spleen, goiter). Sometimes the connection seems so clear that the symptom is not even described, but one speaks directly of the organ. E.g. instead of saying 'a smooth flat body is palpable in the left hypochondrium,' one speaks directly of enlargement of the spleen, although such conclusions are not always correct. For other symptoms the connection with the organ is unclear, and the localization of the symptom cannot be determined (appetite, general condition, elevated temperature). In such cases sometimes a dependence is established between the symptom and some pathological process (e.g. infection and fever or tumor and cachexia). Certain frequently occurring disturbances have also been found that give similar groups of symptoms and often appear in the most diverse diseases (stasis, inflammation). In general, however, it is not important to have a deep explanation of symptoms. For diagnosis, pursuing purely practical aims, it is important that a firm connection, even if not completely understood, with some morbid process or etiological factor has been established. In diagnosis, the attitude toward the symptom is purely semiotic: the symptom is considered as an indicator of certain morbid phenomena in the organism. And just as in chemistry indicators were used without yet having an explanation either for the dependence of color on structural regrouping or for the meaning of pH, so many symptoms, which are used daily, await their detailed study. The connection of symptoms with organs has been discovered by various paths and has been studied to such an extent that, knowing the organ and the nature of the pathological process, one can even enumerate what symptoms will appear in this case. Conversely, starting from the symptom, one cannot without error indicate to which organ it belongs (not all reverse conclusions are true), because the same symptoms can be given by different organs. Therefore, to indicate the diseased organ one can often do so only by taking into account several symptoms pointing to the same organ. The probability of a correct D. increases in this case (e.g. pain in the right hypochondrium and jaundice, protein in urine and casts, etc.). This is the explanation of the advice given to the beginning physician—to as far as possible not make diagnostic conclusions on the basis of one symptom. The more symptoms are explained by one morbid process or lesion of one organ, the more probable, generally speaking, the corresponding D. appears to us. This is especially manifested in cases of fine localization of the focus in various diseases of the nervous system. On the other hand, one is sometimes led into error in this way if one deals with multiple foci (e.g. two tumors). The transition from symptom to organ is already part of D.

But it is not only necessary to know where the cause that produces the symptom is located, but also what it consists of. Most of our diagnostic conclusions contain two statements, one of which indicates the affected organ, and the other speaks of the process that caused the disease of this organ (e.g., cancer ventriculi). All symptoms of the disease are also divided into two groups for these diagnoses. For example, in lobar pneumonia, some symptoms (bronchial breathing, dullness, sputum) indicate a lesion of the lung. These symptoms remain for some time after the crisis, when the patient already feels well. Others speak of inflammation and give a series of signs of intoxication (elevated temperature, disturbance of cardiac activity, etc.); their conclusion marks the crisis and is associated with overcoming the infection. As a result of the interpretation of various symptoms, the clinical picture no longer appears as a disconnected collection of symptoms, but gives way to the concept of disease as a system of affected organs, tissues, and functions. The process of examining the patient and collecting symptoms should be distinguished from the diagnosis itself. Usually both tasks—the examination and the establishment of the diagnosis—are performed simultaneously, but sometimes they can be done at different times and even by different individuals. In the latter case, the one making the diagnosis almost always wishes to see the essential symptoms himself. Only in the case of very characteristic phenomena can one dare to make a diagnosis in the absence of the patient. This is caused not so much by the fact that the person collecting the symptoms could have made a mistake or missed a symptom, but by the fact that the direct impression of the symptom significantly helps in making the Diagnosis. No symptom can be described exhaustively. Small details, shades of color, the luster and dryness of the skin, the impression of the first pectoral sound, bronchial breathing, the density of the spleen, etc.—all of this may prove to be very important. Various phenomena are described as one symptom. Pallor—in septic patients, in malignant anemia, in Bright's disease, during an attack of angina pectoris—all fall under the general definition 'pallor.' For an experienced diagnostician, these symptoms are immediately distinct from one another, although often he cannot explain what the difference consists of. The symptom itself, due to the multitude of unnoted peculiarities, can acquire such a characterizing force that, contrary to the general rule, a conclusion about the disease is made on the basis of one symptom. Of course, the diagnosis should be confirmed as much as possible by other data. The use of subtle, not fully recognized signs for diagnosis forms the basis of the concept of 'intuition' that develops in experienced physicians. Many symptoms are not measurable (jaundice), but even measurement in centimeters and various coefficients often give less than one glance at the patient. When encountering a particular symptom, another very essential diagnostic act is performed: the evaluation of the importance of the symptom. Since the picture of the disease is changeable and some symptoms may even be absent in typical diseases, the question arises: can one diagnose disease A, which usually proceeds with symptoms a, b, c..., if symptom a is absent. The answer to such questions can be obtained by imagining the conditions under which the symptom arises; for example, a heart murmur may not appear if the heart is weakened, or pneumonia may not give a temperature in a very weakened patient. It is also necessary to consider the method of finding the symptom. For example, auscultation with a frequent pulse does not always reveal whether there is a systolic or diastolic murmur. The possibility of palpating the spleen depends on so many reasons (abdominal distension, thickness of subcutaneous fat, position of the organ) that the symptom itself becomes not very reliable. This shows that the absence of one or another clinical sign cannot always be given decisive importance. The clinical manifestation of the disease depends on many circumstances, and therefore every symptom contains an element of chance. When examining the picture of the disease, one encounters another question: is it possible, finding among other signs symptom a, to base the diagnosis of disease A (a, b, c... t), in which this symptom occurs, only on its basis? Such symptoms that would occur in only one disease are few. As a rule, the diagnosis rests not on one, but on several symptoms. Some combinations of signs are so characteristic that they immediately clarify the situation. However, even entire groups of symptoms do not always decide the diagnosis. The question of the reliability of the diagnosis is decided not only by knowledge of the symptoms: in addition to symptoms, other data are also used that clarify the reason for the peculiarities of the clinical picture. One cannot think of the patient outside of a known environment, and therefore the study of living conditions and working conditions gives substantial assistance for the diagnosis; for example, it would be difficult to recognize carbon monoxide poisoning if the environmental conditions did not explain the entire clinical picture. During epidemics, diagnosing an unclear disease as typhus fever is easy in places where outside of an epidemic it would be impossible. Notable clinicians (Zakhar'in, Ostroumov) always attached great importance to the life situation. The anamnesis clarifies a great deal. Already the fact of how a particular disease developed, whether the onset was acute, whether it recurred, etc., is important for excluding various possibilities. But much else is also learned from the anamnesis. A schematic description of the disease changes in each real case. The variability of the disease picture depends on the variability of both the patient's organisms and the surrounding environment; in an exhausted and hungry patient, the symptoms and course will be different than in a well-fed one. The personal characteristics of a particular patient: how he reacts to various harmful influences, various idiosyncrasies, the very important diagnostic indication of the existence of a place of lowered resistance (locus minoris resistentiae)—all these data are clarified from the anamnesis. The doctrine of 'typical individuality' gives the important diagnostic concept of constitution and indicates the methodology for its study. Knowledge of heredity is of great importance, as it speaks of a familial predisposition to various diseases. All these data prepare the ground for recognizing the disease. The diagnosis, which is a strictly logical conclusion from the symptoms, is rarely made in practice; between a convincing conclusion and a poorly substantiated assumption there are many transitions. Ultimately, a definite diagnosis is made on the basis of all diagnostic material not because it cannot be otherwise, but because 'it most often happens this way.' In other words, empirical probability is taken into account. The data are not always sufficient to form an idea of the disease present. Therefore, one cannot assert that a diagnosis can always be made. On the contrary, it is undoubtedly the case in many instances that a diagnosis cannot be made and that recognition of the disease should be abandoned. Meanwhile, life requires a diagnosis, and the physician is left only to make a more or less probable assumption where the diagnosis cannot be sufficiently substantiated. Almost always it is possible to choose from all possibilities several between which the diagnosis fluctuates (differential diagnosis). Atypical pictures of the disease are characterized either by a poverty of symptoms or by a confusion of the clinical picture. In the first case, one can sometimes get out of the difficulty by waiting for some time until new symptoms appear (e.g., at the beginning of an infection); however, this method is a way around the difficulty and is associated with the danger of being late with treatment. In various new growths, for example, the success of therapy depends on early diagnosis and early surgical intervention. Meanwhile, new growths initially give few bright symptoms, and often the diagnosis is only possible in an inoperable state. With a confused clinical picture, the situation is somewhat different. The task that arises in the clinic appears in this form: given a series of symptoms (a, b, c)—to imagine a disease that could underlie them, if it is known that none of the typical symptom complexes is suitable for diagnosis. The diagnosis of such a disease cannot be made by comparison with well-known samples, and the picture of the disease represents a complex combination of circumstances that conscious analysis can only partially dissect. To a greater or lesser degree, such a situation is repeated in every diagnosis. And here observation of the course of the disease, its improvement and worsening, as well as the appearance of new symptoms, can give an answer, although sometimes a belated one. For purely clinical purposes, the diagnosis should note: 1) the primary disease, 2) the so-called complications, i.e., diseases that arise as a result of the primary disease, 3) a concurrent or accidental disease ('every patient has the right to suffer from two diseases'). Thus, observing a case of perforative appendicitis with peritonitis at the same time as arteriosclerosis in the same subject, the diagnosis of the disease should be formulated as follows: appendicitis (main diagnosis), perforative peritonitis (complication), arteriosclerosis (concurrent disease).

Sometimes the diagnosis of the main disease (not to mention the accompanying ones) is extremely complicated by the presence of severe complications; for example, apoplexy of the brain or hemiplegia can be complications of various main diseases, such as arteriosclerosis, brain tumor, certain acute infectious diseases. The formulation of the anatomical diagnosis is made according to the same principle. The desire to obtain as many signs as possible for Diagnosis has led to the invention of numerous research methods. Initially, medicine was satisfied almost exclusively with the data of clinical observation; palpation, pulse examination, and some individual sound symptoms constituted a meager addition to the observation elevated to a cult; only the end of the 18th century and the beginning of the 19th century are marked by the development of the technique of percussion and auscultation. From this time on, research methods are given ever greater importance; this area is diligently developed thanks to the development of natural science and technology: microscope, chemical analysis, bacteriology, X-rays, and many others have become constant tools for diagnosis. At the same time, the technique becomes more complicated, and all research can no longer remain in the hands of one person. Part of it is separated into a specialty that moves to the laboratory or a special office. It is quite clear that the complication of the technique must be justified by the results it gives for the purpose of diagnosis. The laboratory and special office provide new, accurate, and reliable data; one even gets the impression that the diagnosis is made not in the clinic, but in one of the auxiliary institutions. Such a view is not entirely correct: the picture of the disease is often and unexpectedly illuminated by a laboratory symptom (e.g. tuberculosis bacteria in sputum, positive Weber reaction in excreta), the laboratory can give one or more symptoms that immediately decide the diagnosis and do not allow two interpretations, but the diagnosis in the clinical sense requires something else: it requires illumination of the entire picture of the disease. Knowledge of the main pathological process is insufficient for this purpose. Even tuberculosis bacteria in sputum say nothing about the nature of the process, whether it is in the right or left lung, how extensive it is, whether there are cavities, how the disease has reacted on other organs and on the general condition, etc.; meanwhile all these data are extremely important, because from them the prognosis and treatment mainly depend. Just as from laboratory data one can see that the patient has nephritis, but shortness of breath, as well as many other symptoms existing in the patient, receive no explanation from this; their origin is clarified only at the patient's bedside. Diphtheria bacteria do not prove diphtheria disease and can be found even in a healthy carrier; furthermore, the Widal reaction does not yet mean that typhus is present, but may indicate that typhus was once present. The laboratory is not interested in diagnosis; it is concerned with the question of finding this or that given in the analyzed material; responsibility for diagnosis lies with the one who has all the symptoms, i.e. the observing physician. For the latter, laboratory data are no different from all others, and as with every symptom, he must also be able to relate to the laboratory one critically. Many laboratory data are obtained by complex techniques requiring experience and good technique. Bacteriological analysis depends, for example, on the observance of various conditions; in cases where the diagnosis depends on the results of the analysis, the research should be repeated as much as possible, especially if the laboratory's answer disagrees with clinical data. The result of the analysis may sometimes be unconvincing for Diagnosis, despite a categorical answer. One should always keep in mind that laboratory research also depends on when and how the material for analysis was taken (e.g. in diabetes there may be no sugar at all in morning urine). Analysis does not always have decisive significance, and more often the diagnosis is in less direct dependence on the data of analyses (urobilin and bilirubin in urine, absence of hydrochloric acid, sarcines, etc.). In these cases, analyses nevertheless give essential conclusions in combination with clinical data. The development of medical knowledge is due in large part to the laboratory; this has created such credit for laboratory symptoms that many of them are presented as proof without sufficient verification. Thanks to the comprehensive application of penetrating rays, there has been an extremely close rapprochement between diagnosis and radiology. Here research always requires the presence of the patient himself. Radiology has been separated into a special specialty mainly because of the need to have technical special knowledge and technical experience. The radiologist's symptoms are primarily morphological-shadows of organs. Information about the size, shape, and density of organs and deeper parts before the introduction of X-rays into the clinic was obtained by means of palpation, percussion, and partly auscultation-methods in which for diagnosis hearing and touch are applied. Thanks to the discovery of Roentgen it became possible to use for this purpose the eye, which is trusted more than any other sense organ. Both percussion and fluoroscopy, dividing organs hidden from observation, rely on the difference in mass of organs. X-ray research methods have the advantage that the depth of the organ's location does not hinder the research. Moreover, the mutual arrangement of organs is easier to imagine on the basis of the rectilinear projections obtained when researching with X-rays than from the very complex acoustic data of percussion, which until recently were not even explained. From this, however, it does not follow that the new physical method-fluoroscopic-will completely displace the old ones; the latter undoubtedly successfully compete with it in many cases; of course the best results are obtained when using both X-ray methods and old methods together. The greatest productivity is ensured to the fluoroscopic method if it is applied in the presence of the radiologist and the treating physician. The desire to grasp as much as possible with the eye has led to the appearance of a special method-endoscopy. With this method, such body cavities are inspected which without endoscopy would be accessible to inspection only with large wounds due to the narrowness of natural openings and the curvature of channels (cystoscope, gastroscope, rectoscope, laryngoscope). Despite the brilliant results, endoscopy does not always solve the diagnosis; for example, to determine the nature of an ulcer in the rectum or in the larynx, and endoscopy cannot always do so, despite good visibility of the pathological processes. The impossibility to clarify the nature of the pathological process with the naked eye hinders diagnosis in many openly lying ulcers, as well as during various cavity operations. In some cases, microscopy of living tissue is already used for diagnostic purposes, e.g. in capillaroscopy and in ophthalmology (Spaltlampe). Usually, however, a piece of tissue is excised and microscoped according to the general rules of histological technique (biopsy). It is often impossible to accurately determine the nature of suffering hidden in the depths of the abdominal cavity, and many operations are conducted or at least begun with a diagnostic purpose (exploratory laparotomies). Exploratory laparotomies represent a convenient and reliable path for diagnosis in general, and their application should be welcomed, were it not for the dangers associated with them. The methods of research of individual important areas are mastered by specialists. Their often very perfect methods directly detect the location and nature of the disease. Distant and general symptoms as a rule interest the specialist less-all attention is concentrated on the local process, thanks to which sometimes a correct diagnosis is made by a non-specialist who takes into account the entire set of signs. This proves the great value for diagnosis of general and indirect signs of local diseases. Nevertheless, in controversial cases the decision (as much as possible) should be based on the data of direct research, because it is clear that this path gives more convincing results.-Clinical experiment is also attracted to diagnosis. The oldest form of it-Diagnosis ex juvantibus. The conclusion based on the success of treatment is a special case of recognition according to the course of the disease and in uncomplicated circumstances can be convincing (e.g. the patient for a long time suffered from trigeminal neuralgia, which quickly passed from treatment of a tooth, or unclear 'rheumatic' pains in the legs disappeared after mercury treatment). But with the complication of treatment and less clarity of the picture, the reliability of the proof ex juvantibus is small. Diagnosis ex juvantibus loses meaning with multidirectional therapy conducted simultaneously. Anatomical and functional diagnosis. Since clinical conclusions speak about anatomical changes, they are easily verified by autopsies or various research methods (endoscopy, examination, biopsy, etc.). Things are worse with all sorts of functional deviations, which for clinical medicine have no less importance; the ordinary concept of health is even more connected with function than with structure. It is also known that the parallelism of anatomical and functional changes is incomplete. Therefore it is necessary to approach the study of the disordered function directly, as physiology has long done for normal functions.

For this purpose, every function is considered as an experiment conducted under known conditions. For correct conclusions and observations, uniform experimental conditions must be created (pupil reflexes should be checked with relaxed accommodation, sugar in urine should be examined after eating). As clinical research developed, stricter requirements began to be applied to the study of function. Initially, one can be satisfied with a single qualitative study of function and obtain only 'yes' or 'no' answers during research (for example, HCl may be absent or present in gastric juice). Later, it became desirable to have a more complete understanding of organ activity and to develop methods for studying altered functions. In this area, there are still many difficulties, since what is simply called function in many cases must be broken down into several different functions; the kidney, for example, is a complex organ which, on one hand, excretes water, and on the other, a whole range of salts and organic substances. These functions can become independently disrupted in diseases and must be studied separately for diagnosis. In very severe lesions, when the question concerns the functional death of an organ, the investigation is simplified, and one can make conclusions about all other functions based on the absence of any one function. Such conclusions are justified in many, but not all, cases. The question of function is greatly complicated by the fact that it is difficult to separate organ function from the entire organism. The concept of an organ is first and foremost an anatomical concept; what is attributed to the activity of only the organ depends to a large extent not on itself. Water is retained and kidney secretion is reduced not only depending on whether the kidney is working strongly or weakly. Similarly, the retention of NaCl excretion is not in all cases evidence of kidney tissue damage. Because of this, the methodology of functional diagnosis, consisting of giving the body certain tasks, sometimes yields answers of such generality that it is difficult to draw conclusions about the activity of any particular organ from them (diuresis in edema). (For functional diagnosis of various organs, see the respective organs.) There are many symptoms (both subjective and objective) suitable for diagnosis. Some of them are obtained with great difficulty, and it is of course impossible to perform all investigations on each patient. Therefore, one beginning a Diagnosis initially uses simple, easily performable methods and begins to analyze the recognizable picture of the disease with an easily accessible symptom (in choosing it, the diagnostician is not restricted). Any bright symptom can serve for this purpose, but usually the diagnosis begins with considering the patient's complaints, which immediately direct attention in a certain direction (the physician finds himself in a difficult position when there are no guiding indications from the patient for diagnosis in cases where the patient, without presenting complaints, wishes to check his health). The complaints are supplemented by the simplest of all research methods - questioning; further investigation is largely just a control by objective methods of what has been obtained through questioning. Methodical reasoning alternates with various investigations, the diagnosis develops, becomes more and more complete and convincing. Complex methods are introduced only as needed. The simplest investigations of life-important organs must always be performed in order not to miss any symptom that may lie aside from the general path of diagnosis. Following the development of diagnosis, one can notice that the speculative diagnosis, based on the simplest clinical symptoms and subtle reasoning, is passing into the realm of tradition. It retains heuristic value, but the center of gravity of diagnosis is increasingly (as much as possible) transferred to direct investigation, thanks to which the diagnosis becomes more convincing and accessible. Assuming that before us is a sick person and that each disease has its own specific signs, one should strive to make a diagnosis based only on what the status provides; give more - the objective status (of course, this assumes great perfection of knowledge and the ability to investigate everything necessary for the diagnosis).