A Pap smear (Papanicolaou test) is a routine screening method that detects abnormal cells on the cervix that could potentially lead to cancer. The test involves collecting and examining a small cell sample under a microscope. While an abnormal result can be alarming, it is a common finding and does not typically indicate cancer. It means some cells look unusual and require further monitoring or attention. Most changes found are not severe and often resolve on their own.
Common Non-HPV Causes of Abnormal Findings
A variety of temporary, non-precancerous conditions can cause cervical cells to appear atypical during a Pap test. One frequent cause is inflammation (cervicitis), which irritates the cervical tissue and alters the appearance of cells. This cellular change is often reactive, meaning the cells are responding to an irritant.
Benign infections are another common source of abnormal results, as they change the cellular structure seen by the pathologist. Infections such as bacterial vaginosis (BV), yeast infections, and trichomoniasis cause irritation and inflammation. These infections are treatable with medication, and subsequent Pap tests usually return to normal once the infection clears.
Hormonal fluctuations, particularly those related to menopause or pregnancy, can also affect cervical cells. For example, the lack of estrogen after menopause can cause tissue thinning (atrophy), making cells look altered. Sometimes, an abnormal reading is due to a technical issue, such as an insufficient sample collection or recent sexual activity. In these cases, the test is repeated after a short period to ensure an adequate sample is obtained.
Understanding Precancerous Cellular Changes
The most significant cause of abnormal Pap smear results is the Human Papillomavirus (HPV), a common sexually transmitted infection. High-risk types of HPV are responsible for nearly all cases of cervical cancer, but the infection usually causes precancerous cellular changes. Pathologists use a standardized reporting system called the Bethesda System to classify the degree of abnormality found in the cervical cells.
The mildest category is Atypical Squamous Cells of Undetermined Significance (ASC-US), indicating cells look slightly abnormal but the cause is unclear. Following this are Low-Grade Squamous Intraepithelial Lesions (LSIL), which often represent a temporary HPV infection. LSIL is equivalent to mild dysplasia (CIN 1), and these low-grade changes frequently clear up spontaneously.
More concerning results include High-Grade Squamous Intraepithelial Lesions (HSIL), which encompass moderate to severe dysplasia (CIN 2 or CIN 3). HSIL suggests a greater degree of cellular change and a higher probability of progressing to cancer if left untreated. Less common are Atypical Glandular Cells (AGC), which originate from glandular tissue deeper in the cervix or uterus. High-grade lesions nearly always require intervention to remove the abnormal tissue and prevent progression.
Navigating Follow-Up and Treatment Options
An abnormal Pap result initiates a clinical pathway determined by the severity of the cellular changes reported. For mild abnormalities like ASC-US, the provider may order a reflex HPV test to check for high-risk HPV strains. If high-risk HPV is detected, or if the initial result was LSIL or higher, the next common step is a colposcopy.
A colposcopy is a diagnostic procedure where the cervix is examined using a specialized magnifying instrument. During this in-office procedure, a mild acetic acid solution is applied to the cervix, which temporarily turns abnormal areas white. If suspicious areas are identified, a small tissue sample (biopsy) is taken and sent to a lab for definitive analysis.
If the biopsy confirms moderate to severe precancerous lesions (HSIL), a treatment procedure is usually recommended to remove the affected tissue. Common excisional treatments include the Loop Electrosurgical Excision Procedure (LEEP) or cryotherapy. LEEP uses a thin, electrically charged wire loop to precisely remove the abnormal section. These interventions aim to prevent the progression of precancerous cells to invasive cancer. Follow-up Pap and HPV tests are typically scheduled every six to twelve months.