ASC-H on a Pap smear of the cervix

by Adnan Karavelic, MD FRCPC
September 25, 2023

What does ASC-H mean?

ASC-H stands for atypical squamous cells, cannot rule out HSIL. It means that abnormal squamous cells were seen in your Pap smear.  These abnormal cells raise the possibility that a more serious pre-cancerous disease called high-grade squamous intraepithelial lesion (HSIL) may be present in your cervix.

Normal cervix

What causes ASC-H?

Causes of ASC-H in the cervix include human papillomavirus (HPV) infection, inflammation, postmenopausal status, prior radiation therapy, and inadvertent sampling of endometrial cells.

Does ASC-H on a Pap smear mean cancer?

No. ASC-H does not mean cancer. However, it can mean that a precancerous condition called high grade squamous intraepithelial lesion (HSIL) may be present in your cervix. For this reason, your doctor may recommend a follow-up Pap smear to rule out the presence of HSIL or similar conditions.

Does ASC-H mean that I have human papillomavirus (HPV)?

Not necessarily. While HPV is a common cause of ASC-H, other conditions that affect the cervix can also cause this change. These conditions include atrophy of the squamous cells in postmenopausal women, metaplastic squamous cells, and inflammation. Normal endometrial cells can also be mistaken for abnormal-looking squamous cells.

What does ASC-H look like under the microscope?

The cells in ASC-H are called atypical because when examined under the microscope they have an abnormal shape and size compared to the healthy squamous cells that are normally found in the cervix. In particular, the part of the cell that holds the genetic material, the nucleus, is larger than normal while the body of the cell is smaller. The atypical cells are also usually darker than normal cells. Pathologists call these cells hyperchromatic. The abnormal cells may be found in small groups or as individual cells.

This image shows abnormal squamous cells from a Pap test that were diagnosed as ASC-H.

Other helpful resources:

Choosing Wisely Canada

Cancer Care Ontario

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