A Pap smear is a routine screening tool designed to detect changes in the cells of the cervix that could potentially develop into cancer. When performed during pregnancy, an abnormal result can cause immediate concern. Pregnancy itself often causes temporary, non-cancerous changes in cervical cells, which may lead to a result flagged as abnormal. Understanding these results in the context of pregnancy is crucial for appropriate monitoring and care.
The Direct Link: How Pregnancy Affects Cervical Cells
The massive surge of hormones, particularly estrogen and progesterone, during pregnancy drives significant physiological changes in the cervix. These hormonal shifts cause cervical cells, especially in the transformation zone, to undergo rapid growth and transformation (metaplasia). These reactive cellular changes can sometimes cause the cells to appear atypical under a microscope, leading to a false alarm on the Pap test. The cervix also becomes highly vascularized, meaning it has increased blood flow. This increased blood supply makes the cervix more sensitive and prone to inflammation and minor bleeding, which complicates cell sample interpretation.
Understanding Abnormal Pap Results During Pregnancy
An abnormal Pap result is categorized using specific terminology that indicates the degree of cellular change observed. The vast majority of abnormal Pap smears detected during pregnancy fall into low-risk categories, which frequently regress spontaneously after delivery.
Categories of Abnormal Results
- Atypical Squamous Cells of Undetermined Significance (ASCUS): The mildest and most common finding, meaning cells look slightly abnormal but the cause is unclear.
- Low-Grade Squamous Intraepithelial Lesion (LSIL): Indicates mild changes often caused by a human papillomavirus (HPV) infection.
- High-Grade Squamous Intraepithelial Lesion (HSIL): Represents significant and moderately to severely abnormal cell changes with a higher potential to become cancer if left untreated.
- Atypical Glandular Cells (AGC): Refers to changes in the mucus-producing cells in the cervical canal or uterus, requiring careful follow-up.
Next Steps: Diagnosis and Monitoring While Pregnant
Following an abnormal Pap result, the standard next step is usually a colposcopy, a visual examination of the cervix using a magnifying instrument. Colposcopy is safe to perform at any point during pregnancy and is the primary tool for detailed assessment. Diagnostic excisional procedures and endocervical sampling are avoided due to the risk of bleeding or pregnancy complications. Biopsies are performed only if there is a strong suspicion of invasive cancer. For most low-grade and even high-grade lesions, monitoring involves repeating the colposcopy every 12 to 24 weeks, or deferring the full diagnostic evaluation until six to twelve weeks postpartum.
Managing Severe Abnormalities During Pregnancy
When a high-grade abnormality (such as HSIL or CIN 2/3) is confirmed by biopsy, treatment is almost always deferred until after delivery. This conservative approach is used because these precancerous conditions progress slowly, and intervention risks (like preterm birth) outweigh the benefits during gestation. Observation via repeated colposcopy is the preferred management strategy throughout the pregnancy. The rare exception is the confirmation of invasive cervical cancer, which requires immediate attention and a complex, multidisciplinary management plan. For high-grade pre-cancerous lesions, the method of delivery is typically not affected, and a vaginal birth is usually safe and preferred.