Atypical squamous cells, cannot rule out HSIL (ASC-H) of the cervix

by Adnan Karavelic, MD FRCPC
March 13, 2022

What does atypical squamous cells, cannot rule out HSIL (ASC-H) mean?

The result atypical squamous cells, cannot rule out HSIL (ASC-H) means that your pathologist saw abnormal-looking squamous cells in your Pap test.  These abnormal cells seen in ASC-H raise the possibility that a more serious pre-cancerous disease called high-grade squamous intraepithelial lesion (HSIL) may be present in your cervix.

What causes ASC-H?

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

Why is ASC-H considered a preliminary result?

ASC-H is considered a preliminary result and not a final diagnosis because some non-cancerous conditions can show similar changes. 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.


What happens after an ASC-H result on a Pap test?

After an ASC-H result, your doctor should refer you to a specialist who will perform a colposcopy. A colposcopy allows your doctor to see the entire outer surface of the cervix. ​ During the colposcopy, the doctor will look for any abnormal areas on the surface of your cervix. If an abnormality is found, the doctor may remove a small tissue sample in a procedure called a biopsy. Your doctor may also take a small sample of tissue from the endocervical canal and endometrium. ​

If the tissue removed at the time of the colposcopy finds a precancerous condition such as HSIL your doctor will talk with you about options to remove the disease. There are many factors to consider when deciding which treatment option is best for you. Talk to your doctor about the options available.

Other helpful resources:

Choosing Wisely Canada

Cancer Care Ontario

A+ A A-