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determination of the nature of a disease or ailment. A clinical diagnosis is based on the medical history and physical examination of the patient: it may be confirmed with X-Rays, CAT Scans (Computerized Axial Tomography), MRI (Magnetic Resonance Imaging), and other laboratory tests. Diagnosis by physical examination includes ascertaining temperature, pulse, and blood pressure and involves the use of palpation, to detect enlarged organs and other abnormalities; tapping, to delineate some of the internal organs; and listening, to interpret sounds from organs such as the heart and lungs. Instruments that facilitate physical examination include the sphygmomanometer for blood pressure; the stethoscopestethoscope
[Gr.,=chest viewer], instrument that enables the physican to hear the sounds made by the heart, the lungs, and various other organs. The earliest stethoscope, devised by the French physician R. T. H. Laënnec in the early 19th cent.
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 for listening to the heart and lungs; the ophthalmoscopeophthalmoscope
, instrument used for examining the inner structure of the eye. The device was invented by the German physiologist H. L. F. von Helmholtz in 1851. His model consisted of three plates of glass pressed together and mounted on a handle at a 45° angle.
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 to examine the inner eye; and the laryngoscope and bronchoscopebronchoscope
, long, tubular instrument with a light at the tip that is inserted through the windpipe and bronchial tubes to examine these structures. By passing other instruments through it, foreign bodies and obstructions can be removed and tissue or secretions may be removed
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 to view the larynx, windpipe, and other air passages. Recent innovations in electronics have made it possible for any of these devices to be fitted with video cameras and lights, so that the interior of the body can be viewed on video monitors and recorded on videotape for future reference. In diagnostic tests, the blood, urine, tissues, and other excretions and secretions of the body are examined for evidence of chemical imbalance, cellular change, and the presence of pathogenic organisms. Exploratory surgery and the insertion of visual equipment through a small incision (e.g., laparoscopy and arthroscopy) may be used to assist in diagnosis.



in medicine, the process of identifying a disease and designating it with accepted medical terminology— that is, making a diagnosis. The science of the methods of making a diagnosis is called diagnostics.

Diagnosis is based on the thorough and systematic study of a patient that includes (1) anamnesis—purposeful questioning concerning the complaints, history of the condition, and history of the life of the patient, (2) physical examination (inspection, palpation, percussion, auscultation), testing of visual and auditory acuity and reflexes with special devices, testing of the range of movements in the joints, and so forth; (3) analysis of the results of laboratory tests of blood and various excretions (feces, urine, sputum, pus, and so forth); X-ray examinations: graphic methods—recording on paper or film the movements of the heart (cardiography), blood vessels (sphygmography), and so forth; electrodiagnostic studies (electrocardiography, electroencephalography, and so forth); endoscopy—inspection of the interior of certain organs (for example, the stomach and urinary bladder) using special optical instruments; biopsy—the study of small pieces of tissue excised from the patient or of material obtained by puncturing bone marrow and lymph nodes with a special needle. In certain diseases, important diagnostic data are obtained with radioactive isotopes (radioisotopic diagnosis). Bacteriological and serological (using serum) methods are very important in diagnosing infectious and allergic diseases. In order to make a diagnosis in difficult cases, physicians sometimes resort to an exploratory operation, so that they may examine and study local changes directly.

In order to identify a disease, it is generally necessary to find a fairly large number of symptoms and combinations of symptoms and to determine their intensity. Since different diseases may share the same symptoms (for example, headache, fever, vomiting), differential diagnosis is used. The starting point is usually the selection of the most characteristic, prominent, and positively known (pathognomonic) symptom. The disease is compared with others that show a similar symptom. Less commonly, the diagnosis is made by excluding similar diseases.

To avoid the errors caused by insufficient medical experience, especially in diagnosing rare diseases, attempts were made starting in the 1950’s to make diagnoses with the help of computers, using symptoms (detected by the physician) whose significance in various diseases was calculated beforehand. Development of this approach (cybernetic medicine) is impeded by the difficulties encountered in evaluating symptoms quantitatively and by the imperfect classification of diseases.

In making a diagnosis, the physician attempts to find the cause of the disease and its accompanying diseases and complications and to assess the severity of the functional disorders (functional diagnosis). He also takes into account the particular physiological characteristics of the patient. Thus, a diagnosis must reflect the characteristics that distinguish a given patient from other patients with the same disease. An early, accurate, and maximally concrete diagnosis facilitates well-considered and efficacious therapy and often makes it possible to forecast possible variations in the course of the disease.

A pathologicoanatomical diagnosis is made post-mortem by a specialist (pathological anatomist) who bases his diagnosis on the study of the findings of the autopsy and on the chemical and microscopic analysis of tissues in comparison with the results of studies made while the patient was living. Pathologicoanatomical diagnosis is of value is finding and analyzing inaccuracies in diagnoses made during life; it is also used in forensic medicine.


Osipov, I. N., and P. V. Kopnin. Osnovnye voprosy teorii diagnoza, 2nd ed. Tomsk, 1962.
Metodicheskie problemy diagnostiki Moscow, 1965. (Collection of articles.)
Brodman, K. “Postanovka diagnoza pri pomoshchi vychislitel’noi mashiny.” In Elektronika i kibernetika v biologii i meditsine. Moscow, 1963. Page 361. (Translated from English.)
Diagnosis in veterinary medicine is divided into general and special diagnosis. The objective of the former is preliminary familiarization with the sick animal (anamnesis); determination of its external appearance; study of the skin, integuments, subcutaneous tissue, superficial lymph nodes, and visible mucosae; and measurement of the body temperature. Special diagnosis involves an examination of the internal organs, blood, urine, gastrointestinal contents, cerebrospinal fluid, and so forth. Inspection, palpation, percussion, probing, catheterization, roentgenoscopic and graphic studies (roentgenoscopy, roentgenography, sphygmography, electrocardiography, and so forth) are among the clinical methods used. Diagnostic allergic tests (tuber-culinization, malleinization, and so forth) are used extensively to diagnose infectious and parasitic diseases. Bioassays (inoculation of living tissues and live animals) are necessary in diagnosing a number of infectious diseases (for example, anthrax, brucellosis, tuberculosis, botulism, and tularemia).


Klinicheskaia diagnostika vnutrennikh boleznei sel’skokhoziaistvennykh zhivotnykh, 2nd ed. Edited by V. I. Zaitsev. Moscow, 1964.



(computer science)
The process of locating and explaining detectable errors in a computer routine or hardware component.
Identification of a disease from its signs and symptoms.
In taxonomic study, a statement of the characters that distinguish a taxon from coordinate taxa.


1. Med
a. the identification of diseases by the examination of symptoms and signs and by other investigations
b. an opinion or conclusion so reached
2. Biology a detailed description of an organism, esp a plant, for the purpose of classification
References in classic literature ?
It confirms my diagnosis, as you doctors express it.
That diagnosis lies aloft in our life or unconscious power.
But you've located the diagnosis all right enough--it's under my coat, near the ribs.
His diagnosis was correct, however, for he was seized with occasional sicknesses, during which he vomited blood and suffered great pain.
He submitted this diagnosis to conscience, and conscience graciously approved and accepted it.
Research by the Alzheimer's Society has revealed that more than half of people living with dementia in Wales have not received a formal diagnosis The report found of 43% of people who have received a diagnosis, many have not had adequate information and support needed to live well with dementia.
The report also identi-fies a number of barriers to receiving a diagnosis of dementia in Wales, including low public awareness, fear and stigma and an under-resourcing of socalled "memory services".
In an observational study of more than 20,000 older adults with pancreatic cancer, 10 antecedent diagnoses were found to be significantly associated with the cancer diagnosis.
When a patient is admitted to hospital, the team of doctors formulate a "working diagnosis," he explained.
Of those, 11,897 had an ICD-9 diagnosis code of 290.
A variety of laboratory tests for diagnosis of histoplasmosis, including fungal culture, histopathology, serologic tests, antigen detection, and molecular methods, have different sensitivities based on clinical manifestations and host status (9).
No one had stopped to consider that a) as a dancer of 18 years, I have far more awareness of my body than most, hence am able to differentiate a normal dancer's ache and pain from an abnormal and worrisome injury; b) as a medical professional, I have enough scientific and clinical know-how to construct my own diagnosis and research the source of my symptoms; c) the generic musculoskeletal exam may not be sensitive enough to pick up injuries on a strong and limber dancer; and d) I had already rested, iced, and souped myself up with enough anti-inflammatories to give me an ulcer.