The Papanicolaou test, commonly known as a Pap test or smear test, is a routine procedure used for health screening. This test involves the collection of cells from the cervix, which is the lower, narrow end of the uterus that opens into the vagina. The purpose of this cell collection is to have the sample examined microscopically in a laboratory. This analysis detects any changes in the cells that may be abnormal or precancerous.
Screening Role and Detection Focus
The Pap test serves as a preventative screening measure rather than a diagnostic tool for established disease. Its primary function is to identify cellular changes, often referred to as dysplasia, that occur before full-blown cervical cancer develops. These precancerous cell changes are overwhelmingly caused by persistent infection with certain high-risk types of the Human Papillomavirus (HPV). HPV is a common sexually transmitted infection, and the Pap test works to find the effects of this virus on the cervical cells. In current practice, the Pap test is often performed alongside an HPV test, known as co-testing, to provide a more comprehensive assessment of risk.
The Examination Process and Preparation
Patients should follow preparation guidelines before the appointment to ensure the accuracy of the test. For approximately two days prior, it is recommended to avoid sexual intercourse, douching, and using any vaginal creams, spermicides, or medicines. These actions can potentially wash away or obscure the cervical cells, making the laboratory analysis less reliable. Scheduling the test outside of the menstrual period is also ideal, as heavy bleeding can interfere with the sample quality.
The physical procedure is quick, typically lasting only a few minutes. The patient lies on an exam table with their feet supported in stirrups, similar to a regular pelvic exam. A healthcare provider gently inserts an instrument called a speculum into the vagina to hold the walls open and allow a clear view of the cervix. Next, a small collection tool, such as a brush or a spatula, is used to gently swab cells from the surface of the cervix. Screening frequency varies based on age and previous results; many guidelines suggest screening starting around age 25 with primary HPV testing every five years, or co-testing every five years until age 65.
Interpreting the Results Terminology
The results of a Pap test are classified using specific terminology that describes the appearance of the cervical cells. The most favorable result is “Negative for Intraepithelial Lesion or Malignancy” (NILM), which means no abnormal cells were found. An “Unsatisfactory” result means the lab sample could not be analyzed due to insufficient cells, or the sample was obscured by blood or mucus, requiring a repeat test.
“Atypical Squamous Cells of Undetermined Significance” (ASCUS) is the most common abnormal finding, indicating cells that look slightly unusual but do not clearly point to a precancerous condition. Low-grade changes are called “Low-grade Squamous Intraepithelial Lesion” (LSIL), which suggests mild abnormalities often associated with HPV infection. LSIL corresponds to Cervical Intraepithelial Neoplasia Grade 1 (CIN 1) and frequently resolves on its own.
More serious findings include “High-grade Squamous Intraepithelial Lesion” (HSIL), which indicates moderately or severely abnormal cells that have a higher likelihood of progressing to cancer if left untreated. HSIL is sometimes referred to as CIN 2 or CIN 3. The result “Atypical Squamous Cells, cannot exclude HSIL” (ASC-H) is also a significant finding, as it means the cells are abnormal enough that a high-grade lesion cannot be ruled out.
Required Actions Following Abnormal Findings
An abnormal Pap test result usually does not mean cancer is present, but it does require further investigation. The first step following a significant abnormal result, such as HSIL or ASC-H, is often a procedure called a Colposcopy. During this procedure, the healthcare provider uses a magnifying instrument called a colposcope to get a highly detailed view of the cervix.
A mild vinegar-like solution is typically applied to the cervix during the Colposcopy, which causes abnormal areas to turn white, making them easier to identify. If suspicious areas are found, a small tissue sample, or biopsy, is taken to confirm the diagnosis and determine the severity of the cell changes. If the biopsy confirms moderate to severe precancerous changes (CIN 2 or CIN 3), treatment is typically recommended.
Common therapeutic procedures to remove the abnormal tissue include the Loop Electrosurgical Excision Procedure (LEEP) or cryotherapy. LEEP uses a thin, electrically charged wire loop to precisely cut away the affected area, often performed in the clinic under local anesthesia. After treatment, patients require regular follow-up Pap and HPV testing to ensure the abnormal cells do not return.