scans-tests-and-screening

What you need to know about a cervical length pregnancy scan

Understanding why you need a cervical length pregnancy scan

Why do I need a cervical length pregnancy scan?

During pregnancy you might be asked to go for a cervical length scan. We explain why you might need one and what it shows.

Cervical length pregnancy scan

During pregnancy you might be asked to go for a cervical length scan. These are totally safe and are done via ultrasound. Your cervix is where your womb opens into your vagina and the scan is able to show whether your cervix is opening, which happens before your baby is due.

Why do I need a cervical length scan?

Your cervix should be closed throughout pregnancy and opens just before you give birth. As your body gets ready for labour your cervix softens and shortens which causes the mucus plug that has sealed the entrance to your womb (uterus) during your pregnancy to come away.


If you do have a scan and the cervix is opening early there is the possibility that you’ll be able to get a cervical stitch. This prevents the cervix opening further and keeps the mucus plug in. The stitch will be removed a few weeks before your due date.  If you’re later than 16 weeks doctors may be worried about the safety of the baby as well as risk of infection. 

Who has a scan?

You may be asked to have a scan if you’re expecting twins, if you’ve had surgery, if you’ve previously had a late miscarriage or your baby was premature. If you do have a scan you will normally have one at 16 weeks, 20 weeks24 weeks and if your cervix is closed you’ll have no further scans. Sometimes you’ll get fortnightly scans during the second trimester and vaginal swabs to look for infection.


What you need to know about a cervical length pregnancy scan