A pap smears tests a sample of cells from your cervix to detect pre-cancerous changes or cancer. A pap smear can detect several different types of abnormal cells. The type of cells, their shape and size and color all indicate whether the changes are benign or pre-cancerous, or if you have cancer. Sometimes your doctor cannot tell why the cells look different, but in other cases the abnormal cells might result from infection with human papillomavirus (HPV) or from cervical cancer.
Unknown Cause
Normally your cervix has small, thin, flat cells called squamous cells lining the surface. Sometimes a pap smear detects minor changes in these cells that make them look abnormal, but they are likely not pre-cancerous. A bacterial infection, hormonal changes or a polyp or cyst could all cause abnormal cells in your pap smear.
If you have abnormal cells that do not look pre-cancerous, your pap smear is typically coded positive, and the results might read ASC-US for atypical squamous cells-undetermined significance. Your doctor might test you for HPV. If you have HPV, she might want to monitor you more closely for additional changes. If you do not have HPV, then the atypical squamous cells are probably not a cause for concern.
HPV Infection
Human papillomavirus causes genital warts and some strains can cause cervical cancer. Infection with any strain of HPV can change the cells in your cervix and cause a positive pap smear. If you are infected with a low-risk strain of HPV your body will probably fight off the virus and your pap smear will be normal on your next annual test. If you have a persistent infection with a high-risk strain of HPV, your pap smear might show abnormal cells coded ASC-H or LSIL. ASC-H indicates abnormal squamous cells with a higher risk of being pre-cancerous. LSIL indicates low-grade squamous intraepithelial cells that are pre-cancerous with the risk of developing into cancer year later. HSIL indicates high-grade squamous intraepithelial cells that are severely abnormal with a strong chance that they will develop into cancer.
Cervical Cancer
Cancer causes cells to grow out of control and changes the cell's genetic code, making cancer cells look very different their normal counterparts. Several types of abnormal cells indicate that you have cervical cancer. Cancer of the lining of your cervix, called squamous cancer, shows in severely abnormal squamous cells. Cancer of the glands of your cervix near its opening (adenocarcinoma) produces severely abnormal glandular cells. If the cancer spreads beyond the surface layer, your pap smear might show cervical epithelial neoplasia (CIN) cells, graded from 1 (least serious) to 3 (most serious).
