Schiller Test - Screening of Cervical Cancer

Schiller test is a test that can be used during gynecological examination to help the doctor find areas with suspicious lesions in the cervix.

Schiller test
Schiller test

Schiller test is named after the doctor Walter Schiller, who around 1930 described the method of researching cancer cells in the cervix by staining the same with an iodine-based solution, lugol solution call or Schiller solution.

An alternative embodiment of the Schiller Test can be done by replacing the Lugol solution of acetic acid (vinegar).

In this article we will explain what the Schiller test, what are your applications currently in the screening of cervical cancer and what the results mean positive Schiller test and negative Schiller test.

What is Schiller test?

One of the goals of the gynecological examination is directly visualize the cervix, also called uterine cervix. In many cases, only the naked eye is possible to note the presence of lesions on the cervix, either typical inflammatory lesions of cervicitis, ulcers, sores, etc. Schiller test and the test of acetic acid are made to increase our ability to identify areas of cervical lesions, which frequently may appear normal to the naked eye.

The test is done with a swab, a kind of very long cotton swab. The gynecologist soaks the tip of the swab which is coated cotton, with iodine (or acetic acid) and "paint" the entire cervical region, as if using a brush. After a minute of waiting, the doctor back to visualize the cervix to try to identify areas that were little stained.

The logic behind the test is the following: normal cells of the cervix and the vagina are rich in glycogen, a large molecule made of several small glucose molecules. Iodine can impregnate the tissues rich in glycogen, keeping the dark (painted). Since cancer cells or precancerous are poor in glycogen and therefore not impregnated with iodine, while remaining lighter, usually yellowing, and easily distinguishable from the rest of the healthy tissue that remained stained brown (Colour iodine).

We call positive Schiller test every time there is some yellowish area of the cervix, which is not colored with the lugol, suggesting the presence of atypical cells. On the other hand, the negative Schiller test occurs when the entire cervix is stained brown, indicating the presence of tissue rich in glycogen and therefore healthy for the entire painted area. When there are areas that do not stain, but are not yellowed, in general, we believe that the test is negative.

The test acetic acid has a similar logic, but the mechanism is different. Acetic acid dehydrated cells heterogeneously, and its most pronounced effect on atypical cells than in healthy cells. The end result is a light gray staining throughout the tissue is composed of cells suspected.

There are large differences in outcome between the two tests. Staining with acetic acid should be the test of choice for women with iodine allergy history.

The presence of white spots in the cervix after the use of acetic acid or the absence of iodine impregnation in certain areas stained with Lugol indicate the performance of colposcopy and biopsy tissue, if any visible changes in tissue morphology unstained. Schiller positive test does not necessarily indicate the existence of a cancer. It is only the first step in tumor screening.

Utility of Schiller test

The great advantage of Schiller test is the fact that it is very cheap and is available even in areas with few technical resources. Another advantage is the absence of significant and absolute contraindications, side effects (the patients with allergy to iodine may use acetic acid).

The test Schiller and acetic acid have been widely used for decades by gynecologists as a way to track malignant lesions of the cervix. However, in recent years its use as a screening test has become less frequent, particularly in areas with easy access to new medical and laboratory features.

Currently, the most common way to track cervical cancer is through Pap test, also called cervical cytology test. During the pelvic exam, the doctor collects cervical material and its hole with a trowel and a brush in order to capture cells so a pathologist can view them under a microscope, looking for malignant cells. The material collected in the pap smear can also be used for HPV research, which is the virus that causes the appearance of cervical cancer.

The Schiller and acetic acid testing may be falsely positive in menopausal women or in cases of cervicitis (inflammation / infection of the uterine cervix). It is also good to remember that not all poor cells in glycogen are necessarily malignant or premalignant. Therefore, many doctors staining of the uterine cervix as lugol or acetic acid no longer considered necessary because the pap smear is a more reliable and lower rates of false positives and false negative test.

However, although they are no longer used as a screening test, Schiller or acetic acid test are further useful for the gynecologist. If the Pap test is suggestive of premalignant lesion, the patient must undergo a colposcopy with biopsy of the cervix to rule out the existence of a cancer in early stages. During this procedure, the use of Lugol or acetic acid helps the gynecologist to identify suspicious areas and choose the best spots to be biopsied.

So now, in areas with resources, the use of Schiller or acetic acid test usually restricted to those patients who will be submitted to biopsy of the cervix. In the poorest places, with fewer resources and without access to Pap test, the Schiller test may also be used as an option for screening of cervical cancer.

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