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Medical diagnosis (abbreviated Dx, Dx, or Ds) is the process of determining which
disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
or condition explains a person's symptoms and signs. It is most often referred to as diagnosis with the medical context being implicit. The information required for diagnosis is typically collected from a
history History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the invention of writing systems is considered prehistory. "History" is an umbrella term comprising past events as well ...
and physical examination of the person seeking medical care. Often, one or more diagnostic procedures, such as
medical test A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, diagnostic imaging, genetic ...
s, are also done during the process. Sometimes
posthumous diagnosis A retrospective diagnosis (also retrodiagnosis or posthumous diagnosis) is the practice of identifying an illness after the death of the patient (sometimes in a historical figure) using modern knowledge, methods and disease classifications. Altern ...
is considered a kind of medical diagnosis. Diagnosis is often challenging because many signs and symptoms are nonspecific. For example, redness of the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...
( erythema), by itself, is a sign of many disorders and thus does not tell the healthcare professional what is wrong. Thus differential diagnosis, in which several possible explanations are compared and contrasted, must be performed. This involves the correlation of various pieces of information followed by the recognition and differentiation of patterns. Occasionally the process is made easy by a sign or symptom (or a group of several) that is pathognomonic. Diagnosis is a major component of the procedure of a doctor's visit. From the point of view of
statistics Statistics (from German: '' Statistik'', "description of a state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, indust ...
, the diagnostic procedure involves
classification test Given a population whose members each belong to one of a number of different sets or classes, a classification rule or classifier is a procedure by which the elements of the population set are each predicted to belong to one of the classes. A perfe ...
s.


Medical uses

A diagnosis, in the sense of diagnostic procedure, can be regarded as an attempt at classification of an individual's condition into separate and distinct categories that allow medical decisions about treatment and prognosis to be made. Subsequently, a diagnostic opinion is often described in terms of a disease or other condition. (In the case of a wrong diagnosis, however, the individual's actual disease or condition is not the same as the individual's diagnosis.) A diagnostic procedure may be performed by various
healthcare professional A health professional, healthcare professional, or healthcare worker (sometimes abbreviated HCW) is a provider of health care treatment and advice based on formal training and experience. The field includes those who work as a nurse, physician ( ...
s such as a physician, physiotherapist, dentist,
podiatrist A podiatrist ( ) is a medical professional devoted to the treatment of disorders of the foot, ankle, and related structures of the leg. The term originated in North America but has now become the accepted term in the English-speaking world for ...
, optometrist, nurse practitioner,
healthcare scientist A healthcare scientist or medical scientist is a scientist working in any of a number of health related disciplines. Healthcare scientists may work directly for health service providers, or in academia or industry. Healthcare scientists typically ...
or physician assistant. This article uses ''diagnostician'' as any of these person categories. A diagnostic procedure (as well as the opinion reached thereby) does not necessarily involve elucidation of the etiology of the diseases or conditions of interest, that is, what ''caused'' the disease or condition. Such elucidation can be useful to optimize treatment, further specify the prognosis or prevent recurrence of the disease or condition in the future. The initial task is to detect a medical indication to perform a diagnostic procedure. Indications include: * Detection of any deviation from what is known to be normal, such as can be described in terms of, for example,
anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having i ...
(the structure of the human body),
physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemic ...
(how the body works),
pathology Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in ...
(what can go wrong with the anatomy and physiology),
psychology Psychology is the science, scientific study of mind and behavior. Psychology includes the study of consciousness, conscious and Unconscious mind, unconscious phenomena, including feelings and thoughts. It is an academic discipline of immens ...
(thought and behavior) and
human homeostasis In biology, homeostasis (British also homoeostasis) (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and i ...
(regarding mechanisms to keep body systems in balance). Knowledge of what is normal and measuring of the patient's current condition against those norms can assist in determining the patient's particular departure from homeostasis and the degree of departure, which in turn can assist in quantifying the indication for further diagnostic processing. * A complaint expressed by a patient. * The fact that a patient has sought a diagnostician can itself be an indication to perform a diagnostic procedure. For example, in a
doctor's visit A doctor's visit, also known as a physician office visit or a consultation, or a ward round in an inpatient care context, is a meeting between a patient with a physician to get health advice or treatment plan for a symptom or condition, mo ...
, the physician may already start performing a diagnostic procedure by watching the gait of the patient from the waiting room to the doctor's office even before she or he has started to present any complaints. Even during an already ongoing diagnostic procedure, there can be an indication to perform another, separate, diagnostic procedure for another, potentially concomitant, disease or condition. This may occur as a result of an
incidental finding Incidental medical findings are previously undiagnosed medical or psychiatric conditions that are discovered unintentionally and during evaluation for a medical or psychiatric condition. Such findings may occur in a variety of settings, including ro ...
of a sign unrelated to the parameter of interest, such as can occur in comprehensive tests such as radiological studies like magnetic resonance imaging or blood test panels that also include blood tests that are not relevant for the ongoing diagnosis.


Procedure

General components which are present in a diagnostic procedure in most of the various available methods include: * Complementing the already given information with further data gathering, which may include questions of the medical history (potentially from other people close to the patient as well), physical examination and various
diagnostic test A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, diagnostic imaging, genetic ...
s.
A diagnostic test is any kind of
medical test A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, diagnostic imaging, genetic ...
performed to aid in the diagnosis or detection of disease. Diagnostic tests can also be used to provide prognostic information on people with established disease. * Processing of the answers, findings or other results. Consultations with other providers and specialists in the field may be sought. There are a number of methods or techniques that can be used in a diagnostic procedure, including performing a differential diagnosis or following medical algorithms. In reality, a diagnostic procedure may involve components of multiple methods.


Differential diagnosis

The method of differential diagnosis is based on finding as many candidate diseases or conditions as possible that can possibly cause the signs or symptoms, followed by a process of elimination or at least of rendering the entries more or less probable by further
medical test A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, diagnostic imaging, genetic ...
s and other processing, aiming to reach the point where only one candidate disease or condition remains as probable. The result may also remain a list of possible conditions, ranked in order of probability or severity. Such a list is often generated by computer-aided diagnosis systems. The resultant diagnostic opinion by this method can be regarded more or less as a diagnosis of exclusion. Even if it does not result in a single probable disease or condition, it can at least rule out any imminently life-threatening conditions. Unless the provider is certain of the condition present, further medical tests, such as medical imaging, are performed or scheduled in part to confirm or disprove the diagnosis but also to document the patient's status and keep the patient's medical history up to date. If unexpected findings are made during this process, the initial hypothesis may be ruled out and the provider must then consider other hypotheses.


Pattern recognition

In a pattern recognition method the provider uses experience to recognize a pattern of clinical characteristics. It is mainly based on certain symptoms or signs being associated with certain diseases or conditions, not necessarily involving the more cognitive processing involved in a differential diagnosis. This may be the primary method used in cases where diseases are "obvious", or the provider's experience may enable him or her to recognize the condition quickly. Theoretically, a certain pattern of signs or symptoms can be directly associated with a certain therapy, even without a definite decision regarding what is the actual disease, but such a compromise carries a substantial risk of missing a diagnosis which actually has a different therapy so it may be limited to cases where no diagnosis can be made.


Diagnostic criteria

The term ''diagnostic criteria'' designates the specific combination of signs and symptoms, and test results that the clinician uses to attempt to determine the correct diagnosis. Some examples of diagnostic criteria, also known as clinical case definitions, are: * Amsterdam criteria for hereditary nonpolyposis colorectal cancer *
McDonald criteria The McDonald criteria are diagnostic criteria for multiple sclerosis (MS). These criteria are named after neurologist W. Ian McDonald who directed an international panel in association with the National Multiple Sclerosis Society (NMSS) of America ...
for multiple sclerosis * ACR criteria for systemic lupus erythematosus * Centor criteria for strep throat


Clinical decision support system

Clinical decision support system A clinical decision support system (CDSS) is a health information technology, provides clinicians, staff, patients, or other individuals with knowledge and person-specific information, to help health and health care. CDSS encompasses a variety of ...
s are interactive computer programs designed to assist health professionals with decision-making tasks. The clinician interacts with the software utilizing both the clinician's knowledge and the software to make a better analysis of the patients data than either human or software could make on their own. Typically the system makes suggestions for the clinician to look through and the clinician picks useful information and removes erroneous suggestions. Some programs attempt to do this by replacing the clinician, such as reading the output of a heart monitor. Such automated processes are usually deemed a "device" by the FDA and require regulatory approval. In contrast, clinical decision support systems that "support" but do not replace the clinician are deemed to be "Augmented Intelligence" if it meets the FDA criteria that (1) it reveals the underlying data, (2) reveals the underlying logic, and (3) leaves the clinician in charge to shape and make the decision.


Other diagnostic procedure methods

Other methods that can be used in performing a diagnostic procedure include: * Usage of medical algorithms * An "exhaustive method", in which every possible question is asked and all possible data is collected.


Adverse effects

Diagnosis problems are the dominant cause of medical malpractice payments, accounting for 35% of total payments in a study of 25 years of data and 350,000 claims.


Overdiagnosis

Overdiagnosis is the diagnosis of "disease" that will never cause symptoms or death during a patient's lifetime. It is a problem because it turns people into patients unnecessarily and because it can lead to economic waste ( overutilization) and treatments that may cause harm. Overdiagnosis occurs when a disease is diagnosed correctly, but the diagnosis is irrelevant. A correct diagnosis may be irrelevant because treatment for the disease is not available, not needed, or not wanted.


Errors

Most people will experience at least one diagnostic error in their lifetime, according to a 2015 report by the National Academies of Sciences, Engineering, and Medicine. Causes and factors of error in diagnosis are: * the manifestation of disease are not sufficiently noticeable * a disease is omitted from consideration * too much significance is given to some aspect of the diagnosis * the condition is a rare disease with symptoms suggestive of many other conditions * the condition has a rare presentation


Lag time

When making a medical diagnosis, a lag time is a delay in time until a step towards
diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine "cause and effect". In systems engin ...
of a disease or condition is made. Types of lag times are mainly: * ''Onset-to-medical encounter lag time'', the time from onset of symptoms until visiting a health care provider * ''Encounter-to-diagnosis lag time'', the time from first medical encounter to diagnosis ** Lag time due to delays in reading x-rays have been cited as a major challenge in care delivery. The Department of Health and Human Services has reportedly found that interpretation of x-rays is rarely available to emergency room physicians prior to patient discharge. Long lag times are often called "diagnostic odyssey".


History

The first recorded examples of medical diagnosis are found in the writings of Imhotep (2630–2611 BC) in ancient Egypt (the Edwin Smith Papyrus). A Babylonian medical textbook, the ''Diagnostic Handbook'' written by Esagil-kin-apli (
fl. ''Floruit'' (; abbreviated fl. or occasionally flor.; from Latin for "they flourished") denotes a date or period during which a person was known to have been alive or active. In English, the unabbreviated word may also be used as a noun indicatin ...
1069–1046 BC), introduced the use of empiricism,
logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from prem ...
and rationality in the diagnosis of an illness or
disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
. Traditional Chinese Medicine, as described in the Yellow Emperor's Inner Canon or Huangdi Neijing, specified four diagnostic methods: inspection, auscultation-olfaction, interrogation, and palpation.
Hippocrates Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history o ...
was known to make diagnoses by tasting his patients' urine and smelling their sweat.


Word

Medical diagnosis or the actual process of making a diagnosis is a cognitive process. A clinician uses several sources of data and puts the pieces of the puzzle together to make a diagnostic impression. The initial diagnostic impression can be a broad term describing a category of diseases instead of a specific disease or condition. After the initial diagnostic impression, the clinician obtains follow up tests and procedures to get more data to support or reject the original diagnosis and will attempt to narrow it down to a more specific level. Diagnostic procedures are the specific tools that the clinicians use to narrow the diagnostic possibilities. The plural of diagnosis is ''diagnoses''. The verb is ''to diagnose, ''and a person who diagnoses is called a ''diagnostician''.


Etymology

The word ''
diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine "cause and effect". In systems engin ...
'' is derived through
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
from the Greek word διάγνωσις (''diágnōsis'') from διαγιγνώσκειν (''diagignṓskein''), meaning "to discern, distinguish".


Society and culture


Social context

Diagnosis can take many forms. It might be a matter of naming the disease, lesion, dysfunction or disability. It might be a management-naming or prognosis-naming exercise. It may indicate either degree of abnormality on a continuum or kind of abnormality in a classification. It's influenced by non-medical factors such as power, ethics and financial incentives for patient or doctor. It can be a brief summation or an extensive formulation, even taking the form of a story or metaphor. It might be a means of communication such as a computer code through which it triggers payment, prescription, notification, information or advice. It might be pathogenic or salutogenic. It's generally uncertain and provisional. Once a diagnostic opinion has been reached, the provider is able to propose a management plan, which will include treatment as well as plans for follow-up. From this point on, in addition to treating the patient's condition, the provider can educate the patient about the etiology, progression, prognosis, other outcomes, and possible treatments of her or his ailments, as well as providing advice for maintaining health. A treatment plan is proposed which may include therapy and follow-up consultations and tests to
monitor Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, West ...
the condition and the progress of the treatment, if needed, usually according to the medical guidelines provided by the medical field on the treatment of the particular illness. Relevant information should be added to the
medical record The terms medical record, health record and medical chart are used somewhat interchangeably to describe the systematic documentation of a single patient's medical history and care across time within one particular health care provider's jurisd ...
of the patient. A failure to respond to treatments that would normally work may indicate a need for review of the diagnosis. Nancy McWilliams identifies five reasons that determine the necessity for diagnosis: * diagnosis for treatment planning; * information contained in it related to prognosis; * protecting interests of patients; * a diagnosis might help the therapist to empathize with his patient; * might reduce the likelihood that some fearful patients will go-by the treatment.


Types

Sub-types of diagnoses include: ;Clinical diagnosis :A diagnosis made on the basis of medical signs and reported symptoms, rather than
diagnostic test A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, diagnostic imaging, genetic ...
s ;Laboratory diagnosis :A diagnosis based significantly on laboratory reports or test results, rather than the physical examination of the patient. For instance, a proper diagnosis of infectious diseases usually requires both an examination of signs and symptoms, as well as laboratory test results and characteristics of the pathogen involved. ;Radiology diagnosis :A diagnosis based primarily on the results from medical imaging studies. Greenstick fractures are common radiological diagnoses. ;Electrography diagnosis: A diagnosis based on measurement and recording of electrophysiologic activity. ;Tissue diagnosis :A diagnosis based on the macroscopic, microscopic, and molecular examination of tissues such as biopsies or whole organs. For example, a definitive diagnosis of
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
is made via tissue examination by a
pathologist Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in th ...
. ;Principal diagnosis :The single medical diagnosis that is most relevant to the patient's
chief complaint The chief complaint, formally known as CC in the medical field, or termed presenting complaint (PC) in Europe and Canada, forms the second step of medical history taking. It is sometimes also referred to as reason for encounter (RFE), presenting pr ...
or need for treatment. Many patients have additional diagnoses. ;Admitting diagnosis :The diagnosis given as the reason why the patient was admitted to the hospital; it may differ from the actual problem or from the ''discharge diagnoses'', which are the diagnoses recorded when the patient is discharged from the hospital. ; Differential diagnosis :A process of identifying all of the possible diagnoses that could be connected to the signs, symptoms, and lab findings, and then ruling out diagnoses until a final determination can be made. ; Diagnostic criteria :Designates the combination of signs, symptoms, and test results that the clinician uses to attempt to determine the correct diagnosis. They are standards, normally published by international committees, and they are designed to offer the best
sensitivity and specificity ''Sensitivity'' and ''specificity'' mathematically describe the accuracy of a test which reports the presence or absence of a condition. Individuals for which the condition is satisfied are considered "positive" and those for which it is not are ...
possible, respect the presence of a condition, with the state-of-the-art technology. ; Prenatal diagnosis :Diagnosis work done before birth ; Diagnosis of exclusion :A medical condition whose presence cannot be established with complete confidence from history, examination or testing. Diagnosis is therefore by elimination of all other reasonable possibilities. ;
Dual diagnosis Dual diagnosis (also called co-occurring disorders (COD) or dual pathology) is the condition of having a mental illness and a comorbid substance use disorder. There is considerable debate surrounding the appropriateness of using a single catego ...
:The diagnosis of two related, but separate, medical conditions or comorbidities. The term almost always referred to a diagnosis of a serious mental illness and a substance use disorder, however, the increasing prevalence of genetic testing has revealed many cases of patients with multiple concomitant genetic disorders. ; Self-diagnosis :The diagnosis or identification of a medical conditions in oneself. Self-diagnosis is very common. ; Remote diagnosis :A type of telemedicine that diagnoses a patient without being physically in the same room as the patient. ;
Nursing diagnosis A nursing diagnosis may be part of the nursing process and is a clinical judgment about individual, family, or community experiences/responses to actual or potential health problems/life processes. Nursing diagnoses foster the nurse's independent p ...
:Rather than focusing on biological processes, a nursing diagnosis identifies people's responses to situations in their lives, such as a readiness to change or a willingness to accept assistance. ;
Computer-aided diagnosis Computer-aided detection (CADe), also called computer-aided diagnosis (CADx), are systems that assist doctors in the interpretation of medical images. Imaging techniques in X-ray, MRI, Endoscopy, and ultrasound diagnostics yield a great deal o ...
:Providing symptoms allows the computer to identify the problem and
diagnose Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine "cause and effect". In systems enginee ...
the user to the best of its ability. Health screening begins by identifying the part of the body where the symptoms are located; the computer cross-references a database for the corresponding
disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
and presents a diagnosis. ; Overdiagnosis :The diagnosis of "disease" that will never cause symptoms, distress, or death during a patient's lifetime ; Wastebasket diagnosis :A vague, or even completely fake, medical or psychiatric label given to the patient or to the
medical record The terms medical record, health record and medical chart are used somewhat interchangeably to describe the systematic documentation of a single patient's medical history and care across time within one particular health care provider's jurisd ...
s department for essentially non-medical reasons, such as to reassure the patient by providing an official-sounding label, to make the provider look effective, or to obtain approval for treatment. This term is also used as a derogatory label for disputed, poorly described, overused, or questionably classified diagnoses, such as pouchitis and senility, or to dismiss diagnoses that amount to
overmedicalization Medicalization is the process by which human conditions and problems come to be defined and treated as medical conditions, and thus become the subject of medical study, diagnosis, prevention, or treatment. Medicalization can be driven by new evid ...
, such as the labeling of normal responses to physical hunger as reactive hypoglycemia. ; Retrospective diagnosis :The labeling of an illness in a historical figure or specific historical event using modern knowledge, methods and disease classifications.


See also

* Diagnosis codes *
Diagnosis-related group Diagnosis-related group (DRG) is a system to classify hospital cases into one of originally 467 groups, with the last group (coded as 470 through v24, 999 thereafter) being "Ungroupable". This system of classification was developed as a collabora ...
* Diagnostic and Statistical Manual of Mental Disorders * Doctor-patient relationship *
Etiology (medicine) Cause, also known as etiology () and aetiology, is the reason or origination of something. The word ''etiology'' is derived from the Greek , ''aitiologia'', "giving a reason for" (, ''aitia'', "cause"; and , ''-logia''). Description In medicin ...
* International Statistical Classification of
Diseases and Related Health Problems (ICD)
* Medical classification * Merck Manual of Diagnosis and Therapy * Misdiagnosis and
medical error A medical error is a preventable adverse effect of care ("iatrogenesis"), whether or not it is evident or harmful to the patient. This might include an inaccurate or incomplete diagnosis or treatment of a disease, injury, syndrome, behavio ...
* Nosology *
Nursing diagnosis A nursing diagnosis may be part of the nursing process and is a clinical judgment about individual, family, or community experiences/responses to actual or potential health problems/life processes. Nursing diagnoses foster the nurse's independent p ...
* Pathogenesis *
Pathology Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in ...
* Prediction * Preimplantation genetic diagnosis * Prognosis * Sign (medicine) * Symptom


Lists

*
List of diagnostic classification and rating scales used in psychiatry The following diagnostic systems and rating scales are used in psychiatry and clinical psychology. This list is by no means exhaustive or complete. For instance, in the category of depression, there are over two dozen depression rating scales tha ...
* List of diseases * List of disorders * List of medical symptoms * :Diseases


References


External links

* {{DEFAULTSORT:Medical Diagnosis Medical terminology Nosology