Differential diagnosis of diseases: types, methods and principles

Differential diagnosis (DD) is the ability to accurately recognize the disease and prescribe the necessary therapy in each case, since many pathologies have the same symptoms, and the approaches and principles of treatment for diseases differ. Thus, such a diagnosis allows you to establish the correct diagnosis in a short period of time and conduct adequate treatment, and as a result, avoid adverse effects.

The concept of DD

Let's look at an example of what it is. A doctor is having a runny nose. It would seem that the diagnosis is known, and nothing needs to be clarified. However, DD is necessary due to the fact that it is not known what causes the common cold: allergies, colds, or other factors. Thus, if the examination was carried out of poor quality, then the patient is inconclusively treated for chronic rhinitis for a long period, which is fraught with the onset of severe consequences in the form of atrophy of the mucous membrane.

Quite serious complications may appear due to the lack of differential diagnosis of cancer pathology. According to statistics, about a third of all malignant neoplasms were not detected initially, and they were treated like another disease. The lack of timely detection of the cause is fraught with the progression and weighting of the clinic pathology. Thus, it is important not only to identify the disease and make a diagnosis, but also to conduct a DD, which is available thanks to the latest technologies and qualified specialists.

DD methods

Differential diagnostic methods consist of the following steps:

• The first is to take an anamnesis, listen to complaints and identify symptoms. The doctor analyzes the information received from the patient and forms an opinion about the causes that provoked the pathology, as well as about impaired functions in the work of some organs and systems. It should be remembered that interviewing a patient is an unreliable diagnostic method, since it does not reflect the real state of the individual, but is based on his subjective judgment.
• The second is direct examination using physical methods. As a result, the clinical picture of the pathology is more accurately determined.
• The third is laboratory diagnostics. It is considered the decisive step in the differential diagnosis of the disease, as it helps to detect deviations in the body.
• The fourth is instrumental. At this stage, the degree of severity, as well as the location of the focus of the disease, is revealed with great accuracy. The following types of examinations are widely used and inspire confidence of medical personnel: endoscopy, ultrasound, radiography, MRI, manometry, cardiography, CT, encephalography, ECG. In some cases, several studies are done using different equipment.
• Fifth, the final diagnosis is made.

In the modern world, specially developed programs for personal computers are beginning to gain immense popularity, which allow partially or fully diagnosing the disease, including differential, reducing valuable time for diagnosis.

Principles of DD

There are certain principles of differential diagnosis, which determine the disease:

1. Comparison of the manifestations of a specific syndrome. Distinguish differences in signs that are observed in the patient and in the clinic of the established disease.
2. If the alleged syndrome has a special feature, and in the case under consideration it is absent, then this is a different syndrome.
3. If the doctor suggests a disease, and the patient has a symptom that is opposite to this disease, then this indicates that such a pathology is absent in the patient.

And, for example, the principles of DD in the abnormal development of children, formulated by V. I. Lubovsky, are as follows:

• Humanity - the timely creation of the conditions necessary for each small individual for the maximum development of his talents.
• Comprehensive study of children - the use of information obtained by all specialists in a collective review.
• Systemic and holistic study - the study of emotional-volitional behavior and cognitive activity of children.
• Dynamic study - take into account when examining children, not only those moments that they can fulfill and know at the time of the examination, as well as their ability to learn.
• A quantitative and qualitative approach in assessing the task done is to take into account not only the result obtained, but also the rationality of the decisions chosen, the method, sequence of actions, persistence in achieving the goal.

DD in the abnormal development of children

Differential diagnosis of child development solves the following problems:

• Making an accurate diagnosis, as well as determining the educational institution where the child will receive corrective and pedagogical education.
• Clarification of the diagnosis, delimitation of similar conditions with different psychophysical deviations.
• Determination of the means and ways of corrective work, as well as a forecast of the educational opportunities and development of the child.

Several areas of differential diagnosis should be distinguished:

• Intellectual disorders - mental retardation, mental retardation.
• Different forms of deficit development - these include disorders of the musculoskeletal system, vision and hearing.
• Violation of behavior and emotional sphere - psychopathy, autism.

To conduct DD, tests are used to help give the phenomenon under study a quantitative description and certain techniques, with their help the levels of the child’s psychological development are determined.

How is DD performed?

After collecting information about the patient, the doctor identifies the main and secondary symptoms of the disease. He further groups them by importance. All signs of the disease are combined into syndromes. Differential diagnosis can be called the basis for the diagnosis of a specific disease. During its implementation, several stages are distinguished:

• Determination of the main syndrome that is observed in the patient, and compilation of a list of probable pathologies.
• A detailed study of all the symptoms, especially the presenter, as well as an assessment of the general condition of the individual, the clinical picture is clarified.
• Comparison of the alleged disease with all those listed. As a result of this process, the main similarities and differences are distinguished.
• The analysis and systematization of information. This stage is called the most creative.
• By comparing all the data, improbable pathologies are excluded. The only correct diagnosis is justified and made.

The success of the differential diagnosis of the disease lies in the ability to correctly correlate objective examination methods and subjective data. An underestimation of a factor leads to a diagnostic error.

Methods for diagnosing caries

The pathological process in the tooth tissues, as a result of which cavity defects appear, is called caries. Depending on its development, the choice of a diagnostic method is also carried out. If caries is a stain and is asymptomatic, then detecting it yourself is almost impossible. Doctor, reveals it using special equipment and tools. The types of differential diagnosis are identical to other medical examination methods. To make a differential diagnosis:

• Visual diagnostics. The doctor examines the oral cavity, paying attention to the spots and roughness areas on the enamel. Using the probe, irregularities on the teeth are revealed, and they are examined from all sides with the help of mirrors.
• Drying. This manipulation is carried out in order to diagnose the primary stage of the disease. The tooth is dried with cotton swabs. Damaged areas look dull.
• Staining. For carrying out use the so-called caries markers: fuchsin or methylene blue. Places damaged by caries, as well as their boundaries, after dyeing, become noticeable.
• X-ray Diagnosis is considered effective in the following cases: to identify deep tooth damage, a latent form of the disease, caries located under the gum or between the walls of the teeth. However, it is not possible to identify the disease at an early stage. Damaged areas of tooth tissue in the picture have a lighter appearance, unlike healthy ones.
• Orthopantomogram. With its help, damage is detected, and an idea of ​​the condition of all the teeth of the individual is obtained. This is a fairly accurate diagnostic method. For its use, a dental tomograph with a low dose of radiation.
• Thermal diagnostics. Cold or hot water irrigate the damaged area of ​​the tooth or apply cotton swabs previously moistened with a liquid of different temperatures. Depending on the pain of the individual, the presence of the disease is determined. If they pass after a few seconds, then this indicates caries, and if the pain bothers longer, the doctor may suspect pulpitis.

In addition, electroodontometry, transluminescence, etc. are used.

The need for DD for dental caries

It is impossible to perform differential diagnosis of teeth using only an examination of the oral cavity. Therefore, to make an accurate diagnosis, the above methods are used. The decision on their advisability is made directly by the attending dentist. The need for such a diagnosis is dictated by the fact that caries can be confused with other dental diseases. In order to distinguish caries from hypoplasia, staining is used, from pulpitis - thermodiagnostics, from non-carious lesions - x-rays. The disease in an advanced stage can provoke pulpitis, periodontitis and surgical intervention may be required.

Clinic and differential diagnosis of chronic pulpitis

The following types of chronic pulpitis are distinguished:

• Fibrous - occurs frequently, its predecessor is acute pulpitis. In an individual, pain mainly occurs during exacerbation. The doctor discovers a rather deep carious cavity. A tooth may differ in color from healthy teeth. Exposure to cold causes pain, which does not pass immediately after the termination of exposure. Tapping individual sections of the tooth is painless. This type of pulpitis is differentiated with acute focal, chronic gangrenous and deep caries.
• Gangrenous - the pain appears from the hot, as well as a change in temperature. At the very beginning, it grows, and then gradually subsides. There is an unpleasant odor from the oral cavity. It looks like a grayish tooth, there is a deep carious cavity. The surface layers of the pulp do not bleed. Percussion does not cause pain. Such pulpitis should be differentiated from chronic fibrous and chronic apical periodontitis.
• Hypertrophic - there are several clinical forms: pulp polyp and granulating. In the first case, the overgrown pulp tissue is covered with epithelial tissues of the gum and is considered a late stage of pathology. In the second case, granulation tissue grows from the cavity of the tooth into a carious cavity. This type of pulpitis is characteristic of children and adolescents. When chewing food, bleeding appears, pain is felt when biting solid foods. The tooth practically does not respond to temperature stimuli. Large dental deposits are observed on the diseased side of the tooth, as the individual spares it when chewing. Differentiate with overgrown granulations from perforation of the bottom of the tooth cavity and with the proliferation of the gingival papilla.

DD of community-acquired pneumonia

Consider the clinic and differential diagnosis of pneumonia that occurs outside the walls of the hospital, i.e., at home. It is also called outpatient. For the selection of adequate therapy, it is desirable to establish a diagnosis in a timely and correct manner, since often the symptoms of pneumonia are identical to other pathologies of the respiratory system, and their treatment methods are different.

In such cases, in order to clarify the diagnosis, differential diagnosis will be required. Pneumonia or pneumonia is a very serious disease. It can end in death, so it is especially important to start treatment in a timely manner, the effectiveness of which depends on the correct diagnosis. With pneumonia, using DD, the following diseases are excluded, having a similar clinic at the very beginning of the pathology:

• Bronchitis. A prerequisite for the occurrence of both diseases are acute respiratory processes. Sputum cough is present in both pneumonia and bronchitis. However, in the first case, the disease is more severe, general intoxication of the body is observed, the temperature rises, there are no wheezing dry rales, and, on the contrary, wet ones appear.
• Lung cancer. Initial symptoms are similar. If you suspect pneumonia, a person is prescribed a course of antibiotic therapy. If there is no result after a week, the patient is examined to exclude or confirm oncology. It is advisable to do the differential diagnosis of lung cancer at an early stage before the symptoms that occur when the tumor grows into nearby tissues and metastasizes.
• Tuberculosis. Diagnostic errors are often found when comparing this pathology and pneumonia. General symptoms: severe intoxication of the body, the presence of sputum, pale skin of the dermis, a temperature above 38 degrees, a dry cough, accompanied by pain. The difference is observed by the following criteria: the effectiveness of taking antibiotics for tuberculosis is absent; a tuberculin test for pneumonia is negative, and for tuberculosis, on the contrary, it is always positive; the results of bacteriological studies show nonspecific microflora in pneumonia, and in tuberculosis - mycobacteria (Koch's bacillus); in pneumonia, local clear infiltrative shadows are seen in pneumonia, and in tuberculosis these shadows are heterogeneous, there are foci of screening.

Thus, it allows you to make an accurate diagnosis of the differential diagnosis, and the treatment will be assigned to the individual adequate taking into account the pathogen that provoked this disease.

Conclusion

DD is a type of examination that provides an opportunity to avoid severe consequences and prescribe ineffective therapy. Its use is especially justified in ambiguous and severe cases. Its significance lies in the fact that for a short period of time, diseases that do not fall under certain signs and factors to establish the correct diagnosis are excluded. Conducting differential diagnosis requires from the doctor deep practical and theoretical skills, developed logical thinking.