What it is

The Pap smear or Papanicolau test, commonly referred to as a "smear," is a valuable screening test for the prevention of women's health. Its function is to identify women at risk of developing cervical (cervix, portio) uterine cancer in the future. The Pap test identifies pre-cancerous lesions (CIN, dysplasia) and very small, often asymptomatic, cervical cancers that can degenerate to malignant forms. Its specificity is high, about 98 %. Early detection of pre-tumoral forms prevents the onset of the tumor itself and allows complete treatment of the lesion with outpatient therapies. Therefore, periodic performance of the examination is a recognized effective means of identifying cellular alterations that precede the onset of cancer by many years. The majority of women with malignancy, in fact, had never had a Pap test during their lifetime. In addition, it offers useful information on a woman's hormonal balance and highlights some sexually transmitted diseases such as Human Papilloma Virus (HPV) and infections caused by local pathogens (Bacteria, Mycetes, Trichomonas, Gardnerella, etc.).

When you should do it 

All women should have regular Pap tests every 1 to 3 years starting at age 25 or the age at which they start having sex until age 65. According to the European and National Oncology Commission Guidelines, all women in the age group of 25 to 65 years should have a Pap test at least every three years, while in the United States the Pap test is performed annually. Some Authors also recommend periodic annual Pap-testing starting from the beginning of sexual activity. According to other Authors after 3 consecutive negative Pap tests, the cadence can also be three years if one has not changed partners and there are no other risk factors. The Pap test can also be performed during pregnancy, preferably by the 8th month of gestation. Virginal women can have a Pap test (without the use of a speculum), even if they have an extremely low risk of developing cervical cancer. Women older than 64 years who have never had a Pap test should have one. Women who have already been vaccinated against the HPV virus should likewise have a regular Pap test even if their risk of cancer is low.

The Pap test can be performed during all phases of the menstrual cycle except during menstruation. Should menstruation occur close to the test, the examination should be postponed and a new appointment arranged. Persons with latex allergies should notify health care providers for the selection of gloves suitable for the procedure. The use of oral or vaginal contraceptives or the presence of an intrauterine IUD do not interfere with the test result. Taking oral or intramuscular medications does not present a contraindication for performing the Pap test. In the 48 hours prior to the test, it is preferable to abstain from sexual intercourse and at least in the 24 hours prior to the test to avoid the insertion inside the vagina of ovules, medicines, intimate solutions, gels, foams, vaginal irrigations, candles, etc. These products could, in fact, alter the Pap test result, making it less reliable.

The Pap-Test is' a very simple, quick and painless examination, except for some discomfort during the sampling. It is performed by the gynecologist in the outpatient clinic during the routine gynecological examination. The patient lies on the couch in the gynecological position. The gynecologist inserts the speculum (a small retractor) into the vagina to visualize the upper part of the vagina and the cervix (neck, portio) of the uterus. At this point, he or she performs cell harvesting of the neck and cervical canal using a soft brush (cytobrush). After the examination there may be small amounts of blood loss that is irrelevant to the progress of the pregnancy.

In the conventional Pap Test, the cells are then smudged and fixed with a spray on a slide. In the liquid-phase Pap Test (Thin prep), cells are placed in a liquid contained in a small jar, and then a machine sets up a cytology preparation on a "thin layer." Next, the cells are stained and examined under a microscope by a pathologist.  

Today, according to more recent indications, the HPV Viral DNA Test can be combined with the Pap-Test.

Results

In Italy, the recommended and most frequently used classification of Pap Test abnormalities is the Bethesda System:

Negative: no evidence of intraepithelial or neoplastic lesion

LSIL: low-grade squamous intraepithelial lesion, including HPV/mild dysplasia, CIN1

HSIL: high-grade squamous intraepithelial lesion, including moderate and severe dysplasia, carcinoma in situ / CIN2, CIN3

AIS: glandular cells suspicious for in-situ adenocarcinoma of the cervix

Carcinoma: squamous carcinoma cells

ASC-US: atypical squamous cells, not further classifiable

ASC-H: atypical squamous cells, HSIL cannot be ruled out

AGC: atypical glandular cells, specifying whether endometrial, endocervical, glandular or not otherwise specified

Adenocarcinoma: Endocervical, endometrial, extrauterine or not otherwise specified adenocarcinoma

CTM: Malignant tumor cells not otherwise specified

In the presence of a positive result, further diagnostic investigation is indicated: colposcopy and possibly biopsy, HPV viral typing, or simple repetition of the Pap-test at short intervals.

Pap test is an effective method for the prevention of invasive cervical cancer. However, its sensitivity is 60-70%. That is, false negatives are possible: tests that come back negative in the presence of cervical cancer. They can occur for a variety of reasons: the lesion was not reached by the sampling or the collection of malignant cells did not occur or the malignant cells were masked by those of inflammation. However, progression to the malignant form is slow, and the lesion can be identified at a subsequent Pap test. Very rarely cervical cancer arises after a negative test but before the next examination (so-called interval cancer).