In medicine, a swab is the removal of the body's own substances, which are located on the surface of mucous membranes or on wounds.

What is a smear?

A medical smear is the removal of endogenous tissue from the surface of wounds or mucous membranes with sterile cotton swabs for further microbiological diagnosis.

Such a swab is then examined by laboratory technology in further steps. Depending on the type of smear, different methods are used for this purpose: For example, the material removed from a smear can be applied to a nutrient medium on which any pathogens that may be present form a culture.

In addition, the material can also be applied to a glass slide and fixed. After staining the appropriate smear, the body's own material can then be evaluated under a microscope. To remove a swab, various instruments can be used. These instruments include, for example, small spatulas or brushes, but also sterile cotton swabs.

Function, effect & goal

A smear is used in medicine, for example in the form of a so-called cytological smear (also referred to as a cell smear) or in the form of a microbiological smear. If a cytological smear is performed, it comes to a removal of certain endogenous cells.

For example, such a swab can help to rule out tumors or to detect a cancer at an early stage. The analysis of removed cells is usually done under the microscope. Usually, special microscopes are used for this purpose, such as the so-called phase-contrast microscope.

For the early detection of cancer, a microbiological smear is used, for example, in gynecology (gynecology). The smear is also referred to here as Pap smear or gynecological portio smear. And also for the early detection of lung cancer, a smear can be taken from the bronchi.

For example, a microbiological smear can be used to further define the sources of infection. For this purpose, material is removed from a wound, for example with a cotton swab. If pathogens of a herd of infection have then been determined, a targeted therapy (for example by the administration of antibiotics) is possible.

However, a microbiological smear can also serve other purposes: If, for example, mucosal cells are removed from the oral cavity, the DNA of a corresponding person can be extracted from it. Such a smear is used, for example, if a paternity is to be demonstrated or parentage reports are to be created or if a genetic fingerprint is performed. Different types of typing may also be the subject of a microbiological smear.

Parts of the body where a swab is taken comparatively frequently are, for example, wounds which heal only slowly. This is often the case with diabetics. In addition, the throat is a body area where smears are often made. For example, a swab serves to confirm diseases such as purulent angina. In gynecology, a smear is usually taken in the form of secretions from the vagina or in the form of cells from the cervix. Among other things, especially a smear of vaginal secretions here confirm a fungal infection or other infections.

Risks & Dangers

As a rule, there are very few risks associated with a smear. If, for example, a smear is taken from the cervix in women, slight spotting may occur in exceptional cases. However, these bleeding are usually harmless and after a short time self-releaving.

In addition to the preponderance of risk of smear a corresponding smear is usually painless. Depending on which culture a woman comes from, however, it is possible that the corresponding patient first has to overcome a pubic border during a gynecological smear. However, this is not related to the smear.

Occasionally, a smear can lead to the risk of the smear having to be repeated. This is the case, inter alia, if sufficient quantities of endogenous material have not been taken or if there are laboratory difficulties in preparing the material.

In the case of a swab used for early detection of cancer, there is also a low risk that a result determined in the laboratory may be defective. For example, so-called 'false-positive' test results occur in some cases. This is the case when a smear is considered conspicuous although the patient is healthy.

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