ASCUS
Meaning of ASCUS: The mildest abnormal result on a cervical screening test, and usually a prompt for a virus test rather than for treatment.
Definition of ASCUS
ASCUS stands for atypical squamous cells of undetermined significance, the mildest abnormal finding reported on a cervical screening sample. The flat surface cells taken from the cervix look slightly unusual, but not enough to say whether the appearance reflects infection, irritation, or an early precancerous change. It is the most common abnormal screening result and most cases resolve without treatment.
What does the result actually mean?
A screening sample collects flat squamous cells from the surface of the cervix. A pathologist or automated system compares their appearance to normal. Cells that look clearly precancerous are graded accordingly. This category exists for the cells that fall short of that: slightly enlarged nuclei or altered shape, changes that inflammation, healing, low estrogen after menopause or infection can all produce. The report is therefore a statement of uncertainty rather than a diagnosis.
What follows the result?
Because the cell appearance cannot settle the question, attention turns to whether high risk human papillomavirus is present, since that virus causes essentially all cervical cancer.
| Virus test result | What it indicates |
|---|---|
| Negative | Risk very low; routine screening intervals resume |
| Positive | Closer look at the cervix with a magnifying instrument |
A human papillomavirus DNA test can often be run on the sample already taken, which avoids a second visit. Where colposcopy follows, any suspicious area is sampled and graded properly.
Is the result a reason to worry?
The absolute risk attached to this result is low. Most abnormalities of this grade reflect a transient infection that the immune system clears within a couple of years, particularly in younger people, and the cells return to normal without intervention. Progression to cancer, when it happens at all, takes many years and passes through recognizable stages that screening is designed to catch. The purpose of following up an uncertain result is to identify the small number of cases that are not going to resolve.
How does it differ from other reported grades?
Reporting runs on a ladder. This category sits at the bottom, above normal. Above it come low grade and then high grade changes, which describe cells with increasingly clear precancerous features. A separate category exists for atypical cells where a high grade change cannot be excluded, and that one is treated more urgently. The grades describe cell appearance, not depth of invasion, and none of them is cervical cancer.
Also known as
Used in a sentence
The screening sample was reported as ASCUS with reflex testing for high risk human papillomavirus.
Good to know
The result reports uncertainty rather than disease, and the presence or absence of high risk human papillomavirus, not the cell appearance alone, determines what follow-up is warranted.