Medical diagnosis (abbreviated Dx or DS) is the process of
determining which disease 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 and physical examination of the
person seeking medical care. Often, one or more diagnostic procedures,
such as diagnostic tests, are also done during the process. Sometimes
posthumous diagnosis is considered a kind of medical diagnosis.
Diagnosis is often challenging, because many signs and symptoms are
nonspecific. For example, redness of the skin (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, the diagnostic procedure
involves classification tests.
2 Medical uses
3.1 Differential diagnosis
3.2 Pattern recognition
3.3 Diagnostic criteria
3.4 Clinical decision support system
3.5 Other diagnostic procedure methods
4 Adverse effects
4.3 Lag time
5 Society and culture
5.2 Social context
5.3 Concepts related to diagnosis
6 See also
8 External links
Main article: History of medical diagnosis
The first recorded examples of medical diagnosis are found in the
Imhotep (2630–2611 BC) in ancient Egypt (the Edwin Smith
Papyrus). A Babylonian medical textbook, the Diagnostic Handbook
Esagil-kin-apli (fl.1069–1046 BC), introduced the use of
empiricism, logic and rationality in the diagnosis of an illness or
disease. Traditional Chinese Medicine, as described in the Yellow
Emperor's Inner Canon or Huangdi Neijing, specified four diagnostic
methods: inspection, auscultation-olfaction, interrogation, and
Hippocrates was known to make diagnoses by tasting his
patients' urine and smelling their sweat.
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, but in
the case of a wrong diagnosis, the individual's actual disease or
condition is not the same as the individual's diagnosis.
A diagnostic procedure may be performed by various health care
professionals such as a physician, physical therapist, optometrist,
healthcare scientist, chiropractor, dentist, podiatrist, nurse
practitioner, 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
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 (the structure of
the human body), physiology (how the body works), pathology (what can
go wrong with the anatomy and physiology), psychology (thought and
behavior) and human homeostasis (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, 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 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
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 tests.
A diagnostic test is any kind of medical test performed to aid in the
diagnosis or detection of disease. Diagnostic tests can also be used
to provide prognostic information on people with established
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.
Main article: 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 tests and other processing until, aiming to reach the point
where only one candidate disease or condition remains as probable. The
final result may also remain a list of possible conditions, ranked in
order of probability or severity.
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
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.
Main article: Clinical case definition
The term diagnostic criteria designates the specific combination of
signs, 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
Amsterdam criteria for hereditary nonpolyposis colorectal cancer
McDonald criteria for multiple sclerosis
ACR criteria for systemic lupus erythematosus
Centor criteria for strep throat
Clinical decision support system
Clinical decision support systems 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
Other diagnostic procedure methods
Other methods that can be used in performing a diagnostic procedure
An example of a medical algorithm for assessment and treatment of
overweight and obesity.
Usage of medical algorithms
An "exhaustive method", in which every possible question is asked and
all possible data is collected. This is often referred to as a
Use of a sensory pill that collects and transmits physiological
information after being swallowed.
Using optical coherence tomography to produce detailed images of the
brain or other soft tissue, through a "window" made of zirconia that
has been modified to be transparent and implanted in the skull.
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.
Main article: 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.
Further information: Medical error
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
the condition has a rare presentation
When making a medical diagnosis, a lag time is a delay in time until a
step towards diagnosis 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
Society and culture
The plural of diagnosis is diagnoses. The verb is to diagnose, and a
person who diagnoses is called a diagnostician. The word diagnosis
/daɪ.əɡˈnoʊsɪs/ is derived through
Latin from the Greek word
διάγνωσις from διαγιγνώσκειν, meaning "to
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.
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
A treatment plan is proposed which may include therapy and follow-up
consultations and tests to monitor 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
Relevant information should be added to the medical record of the
A failure to respond to treatments that would normally work may
indicate a need for review of the diagnosis.
Concepts related to diagnosis
Sub-types of diagnoses include:
A diagnosis made on the basis of medical signs and patient-reported
symptoms, rather than diagnostic tests
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
characteristics of the pathogen involved.
A diagnosis based primarily on the results from medical imaging
studies. Greenstick fractures are common radiological diagnoses.
The single medical diagnosis that is most relevant to the patient's
chief complaint or need for treatment. Many patients have additional
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.
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.
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
possible, respect the presence of a condition, with the
Diagnosis work done before birth
Diagnosis of exclusion
A medical condition whose presence cannot be established with complete
confidence from history, examination or testing.
therefore by elimination of all other reasonable possibilities.
The diagnosis of two related, but separate, medical conditions or
co-morbidities; the term almost always refers to a diagnosis of a
serious mental illness and a substance addiction.
The diagnosis or identification of a medical conditions in oneself.
Self-diagnosis is very common.
A type of telemedicine that diagnoses a patient without being
physically in the same room as the patient.
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.
Providing symptoms allows the computer to identify the problem and
diagnose 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
and presents a diagnosis.
The diagnosis of "disease" that will never cause symptoms, distress,
or death during a patient's lifetime
A vague, or even completely fake, medical or psychiatric label given
to the patient or to the medical records 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, such as the labeling of
normal responses to physical hunger as reactive hypoglycemia.
The labeling of an illness in a historical figure or specific
historical event using modern knowledge, methods and disease
Diagnostic and Statistical Manual of Mental Disorders
International Statistical Classification of
Diseases and Related Health Problems (ICD)
Merck Manual of
Diagnosis and Therapy
Misdiagnosis and medical error
Preimplantation genetic diagnosis
List of diagnostic classification and rating scales used in psychiatry
List of diseases
List of disorders
List of medical symptoms
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^ Jingfeng, C. (2008). "
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^ Making a diagnosis, John P. Langlois, Chapter 10 in Fundamentals of
clinical practice (2002). Mark B. Mengel, Warren Lee Holleman, Scott
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^ Decision support systems. 26 July 2005. 17 Feb. 2009
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Look up diagnosis in Wiktionary, the free dictionary.
Media related to
Medical diagnosis at Wikimedia Commons
Basic medical terms used to describe disease conditions
Acronym or abbreviation
Medical examination and history taking
History of the present illness
Past medical history
Eyes (Ophthalmoscopy, Swinging-flashlight test)
Hearing (Weber, Rinne)
Peripheral vascular examination
Jugular venous pressure
Ankle-brachial pressure index
Murphy's punch sign
Back (Straight leg raise)
Knee (McMurray test)
Wrist (Tinel sign, Phalen maneuver)
Shoulder (Adson's sign)
Mini–mental state examination
Cranial nerve examination
Upper limb neurological examination
Ballard Maturational Assessment
Cervical motion tenderness
Assessment and plan
Allied health professions
Health information management
Medical school (Academic health science centre, Teaching hospital)
Skills / Training