Medical diagnosis (abbreviated as Dx,See List of medical abbreviations: D for variants. 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 a diagnosis with the medical context being implicit. The information required for a diagnosis is typically collected from a history and physical examination of the person seeking medical care. Often, one or more diagnostic procedures, such as medical tests, are also done during the process. Sometimes the 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. The study of patient outcomes following diagnosis is the field of survival epidemiology.
Medical uses A diagnosis, in the sense of diagnostic procedure, can be regarded as an attempt at classification of an individuals 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. A total evaluation of a condition is often termed a diagnostic workup.
A diagnostic procedure may be performed by various healthcare professionals such as a physician, physiotherapist, dentist, podiatrist, optometrist, nurse practitioner, healthcare scientist 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 (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 they have 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 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 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 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 tests 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 slower and structured cognitive processing involved in a differential diagnosis. Such heuristics are important in decision making, but also a major source of medical error, especially with atypical presentations.
This may be the primary method used in cases where diseases are "obvious", or the provider's experience may enable them 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 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 erroneous suggestions.Decision support systems. 26 July 2005. 17 Feb. 2009 <http://www.openclinical.org/dss.html > 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), as well as testing (for example from ionizing radiation) and treatments that may cause harm.
On an individual level it is practically impossible to determine whether a diagnosed condition would have resulted in harm (justifying treatment) or overdiagnosis has occurred. Overdiagnosis is determined with population-based analysis and applies to conditions and the use of diagnostic testing, where overdiagnosis may result in a high number needed to treat. Screening mammography is a notable example for this.
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 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
Long lag times are often called "diagnostic odyssey".
Types Sub-types of diagnoses include:
Clinical diagnosis A diagnosis made on the basis of medical signs and reported symptoms, rather than diagnostic tests 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. Endoscopy diagnosis A diagnosis based on endoscopic inspection and observation of the interior of a hollow organ or cavity of the body. Tissue diagnosis