ASC-US and LSIL are the two most common and mildest abnormal smear test results. ASC-US means atypical cells that cannot be clearly classified, and LSIL means low-grade changes, most often caused by a passing HPV infection. In most cases neither needs treatment — just further checks and follow-up, as decided by your doctor.
What ASC-US means
ASC-US stands for atypical squamous cells of undetermined significance. Put simply: the cytologist saw cells that look slightly different from normal, but not different enough to call them an intraepithelial lesion.
There can be several reasons:
- a passing HPV infection,
- inflammation or a vaginal infection,
- hormonal changes, for example around the menopause,
- dryness and thinning of the lining,
- irritation after sex or after using vaginal medicines.
ASC-US is the most common smear abnormality and in most cases is not linked to any significant change on the cervix.
What LSIL means
LSIL stands for low-grade squamous intraepithelial lesion. The appearance of the cells points to an active HPV infection — the virus alters how the cells look, and the cytologist can see this. On histopathology, LSIL usually corresponds to CIN 1.
Importantly, LSIL is a description of what the cells look like, not a disease. In most women, especially younger ones, the body clears the virus within a year or two and the changes disappear without treatment.
Are ASC-US and LSIL dangerous
Both results are low-risk. They do not mean cancer or a high-grade pre-cancerous change. Their significance is that in a small proportion of women a higher-grade change may be hiding behind this picture, one the smear did not pick up. That is why the result is checked with a further test — not in order to treat, but to make sure nothing more important has been missed.
For a general overview of the Bethesda system and other results (ASC-H, HSIL, AGC), see Abnormal smear test — what does it mean and what next?.
What next — the usual steps
Follow-up depends on the result, your age and whether your HPV status is known. In general:
After ASC-US:
- your doctor will usually order an HPV test — if the smear was liquid-based (LBC), it can be run on the same sample,
- HPV negative — returning to your usual screening schedule or a repeat smear is most often enough,
- HPV positive — colposcopy is usually advised; all the more so for type 16 or 18.
After LSIL:
- in adult women the doctor usually refers for colposcopy,
- in young women (roughly under 25), in whom LSIL very often clears on its own, a common option is watchful waiting with a repeat smear after 12 months,
- in pregnancy colposcopy can be done, but a biopsy is usually postponed until after the birth.
A check-up after 6–12 months is one option, not a rule. Your doctor may suggest it when the picture is mild, HPV is negative or the patient is young. It is not a way of “waiting out” a result that calls for colposcopy.
For help reading an HPV result, see Positive HPV test — what happens next?.
What colposcopy involves
Colposcopy is an examination of the cervix under magnification through a colposcope — an instrument that stays outside the body. It feels much like having a smear taken: a speculum, wiping the cervix with a weak acetic acid solution and often with iodine solution, then examining the image. It takes 10–20 minutes and needs no anaesthetic.
With ASC-US and LSIL the colposcopy picture is often normal or shows only minor changes. If the doctor sees an area that needs assessing, a biopsy may be taken — a small tissue sample for histopathology. Only that result shows whether the change needs treatment or simply monitoring.
How to prepare (2 days without sex, tampons or vaginal medicines; not during a period) is described in the guide on abnormal smear tests.
When not to delay
An ASC-US or LSIL result is not an emergency, but it should not be left without a next step. Book a consultation within the next few weeks if:
- the HPV test found type 16 or 18,
- this is your second abnormal result in a row,
- an earlier abnormal result was never followed up,
- you have bleeding after sex, between periods or after the menopause,
- you have unusual discharge or pain in the lower abdomen.
If your doctor advised a check-up in 6 or 12 months, put the date in your diary and keep it — watchful waiting only works if the next test actually happens.
How it works at Sonar Clinic
ASC-US and LSIL results are discussed by Barbara Ossowska, MD — a doctor in gynaecology and obstetrics training. Within gynaecology and obstetrics she takes LBC smears and HPV tests and performs ultrasound scans.
A possible pathway:
- Gynaecological consultation to discuss the result and agree a plan — 220 PLN.
- HPV test, if not yet done: consultation + LBC smear + HPV test (14 genotypes) — 520 PLN.
- Colposcopy — if the doctor considers it appropriate. Colposcopy will be available at Sonar Clinic soon; until then, the doctor will advise during the consultation where to have the examination.
Bring your smear result and any earlier results you have. To book, call +48 880 018 703 or use online booking on the doctor’s profile. Sonar Clinic is at ul. Gubińska 8A, Wrocław. Consultations are held in Polish; please let us know when booking if you need language support.
This content is for information only and does not replace a medical consultation. If symptoms are sudden or getting worse, contact a doctor or call 112.