A Pap smear is a screening procedure designed to detect changes in cervical cells that could potentially develop into cancer. It involves collecting cells from the cervix for microscopic examination. During pregnancy, intense hormonal fluctuations often lead to benign cellular alterations that can cause the Pap smear result to be classified as “abnormal.” Pregnancy does not cause cancer, but these changes can mimic true cellular dysplasia, resulting in a confusing reading.
Pregnancy’s Impact on Cervical Cells
Gestation introduces profound hormonal shifts, primarily elevated estrogen and progesterone, which dramatically affect the cervical environment. These changes often cause cervical ectropion, where soft glandular cells from inside the canal push onto the visible surface of the cervix. Since these delicate cells are prone to inflammation and irritation, the Pap smear may show reactive cellular changes.
Increased blood flow (hyperemia) makes the cervix softer and more easily injured during sample collection. This inflammation and the presence of reactive glandular cells can lead the smear to be classified as atypical. Additionally, the uterine lining can undergo decidualization, a transformation of stromal cells in response to progesterone.
These decidual cells may shed and be collected during the Pap smear. They are large and can sometimes possess enlarged or atypical-looking nuclei, potentially confusing the pathologist. Understanding that these are temporary, non-cancerous changes related to supporting the pregnancy is important when interpreting an abnormal result.
Understanding Abnormal Pap Smear Results
An abnormal Pap smear means some cells showed changes, but it does not confirm cancer is present. Results are classified using specific terminology to indicate the level of cellular change. The least concerning finding is Atypical Squamous Cells of Undetermined Significance (ASC-US), meaning cells look slightly abnormal, often due to inflammation or infection.
Low-Grade Squamous Intraepithelial Lesion (LSIL) suggests mild cellular changes, often caused by Human Papillomavirus (HPV). LSIL is a low-level abnormality that frequently resolves spontaneously, especially after delivery. High-Grade Squamous Intraepithelial Lesion (HSIL) represents more significant and potentially precancerous changes, indicating a higher likelihood of moderate or severe dysplasia.
The underlying cause for true dysplasia is almost always a persistent infection with high-risk types of HPV. While pregnancy can cause benign changes that mimic these abnormalities, classifications like LSIL and HSIL refer specifically to changes associated with this viral infection. Identifying the specific classification helps determine the appropriate management plan.
Next Steps Following an Abnormal Result
The primary goal following an abnormal Pap smear during pregnancy is to rule out the presence of invasive cervical cancer. For most mild abnormalities like ASC-US or LSIL, the standard approach is watchful waiting, deferring definitive treatment until after delivery. Many low-grade lesions regress on their own once the cervix returns to its non-pregnant state.
If the result indicates a more significant change, such as HSIL, a colposcopy is typically recommended. A colposcopy is a safe procedure during pregnancy that uses a magnifying device to closely examine the cervix. Because of increased blood flow and cervical changes, the examination may be more challenging, so it is often performed by a provider experienced in obstetrical colposcopy.
Invasive Procedures
Biopsies, which involve removing a small tissue sample, are generally avoided unless the colposcopy strongly suggests the presence of invasive cancer. Excisional procedures, such as a Loop Electrosurgical Excision Procedure (LEEP) or cone biopsy, are almost always postponed until after delivery. These procedures carry a risk of complications like preterm birth and are only performed during pregnancy if an immediate cancer diagnosis is suspected.
For high-grade lesions, surveillance is usually maintained through repeat colposcopy and cytology every 12 to 24 weeks during the pregnancy. This careful monitoring ensures that the lesion does not progress, while avoiding procedures that could affect the pregnancy. Postpartum follow-up is then scheduled, typically around four to twelve weeks after delivery, to re-evaluate the cervix and proceed with any necessary treatment.