Pap Test

Pap test checks for changes in the cervix that may become cancer.  The cervix is the opening of the uterus at the top of the vagina.  It is covered by a thin layer of tissue.  This tissue is made up of cells.  As these cells develop, the cells at the bottom layer slowly move to the surface of the cervix.  During this process, some cells may become abnormal or damaged.  Damaged cells grow differently, causing an abnormal pap test.  An Abnormal Pap Test result may mean that further testing and follow up are needed.

The main cause of abnormal pap test results  is infection with HPV (human papillomavirus).  There are many types of HPV, some linked to cancer.  HPV infection is very common in women younger than 20 years. 

If you have an abnormal pap test, some terms can be confusing, most labs use the "Bethesda System" to describe the results. This system uses the term Squamous.  This  refers to the type of tissue that covers the cervix.  With this system your results are placed in several groups.

Normal (negative)

Atypical squamous cells of undetermined significance (ASC -US) - changes in the cervical cells have been found.  The changes are almost always a sign of an HPV infection but may indicate precancer is present.  ASC-US is the most common abnormal Pap test results.

Squamous intraepithelial lesion (SIL) abnormal changes are seen in the cells that may be a sign of precancer.  SIL can be low grade (LSIL) or high grade (HSIL).  LSIL almost always indicates that an HPV infection is present, but may also indicate mild precancer changes.  HSIL indicates more serious changes.  CIS is a severe form of HSIL, most likely to progress to cancer.

Atypical squamous cells (ASC-H) changes in the cervical cells have been found.  These changes are not clearly HSIL, further testing is needed.

Atypical glandular cells (AGC) cell changes are seen that suggest pre-cancer of the upper part of the cervix or uterus.

Cancer - abnormal cells may have spread deeper into the cervix or to other tissues.