Cervical Length Scan

Cervical Length Scan


The cervix length is the measurement of the closed part of the Cervix during pregnancy and can be assessed from 14-16 weeks onward.
This measurement is clinically useful in the prediction of pre-term birth (PTB).

The aim is to determine if the cervix is long enough to hold the pregnancy and to establish the risk of early labor or of late miscarriage.
Cervix length should be measured every two weeks between 14-24 weeks of gestation in women with a history of PTB and 20-24 weeks in women with no history of PTB.


A short cervix cannot provide enough protection for the baby, and is more likely to dilate prematurely. Consequently, having a shorter than normal cervical length can sometimes lead to a premature birth or a late miscarriage.

It is not always necessary to have a Cervical Length Scan during pregnancy. However, your doctor may advise you to have this scan if you have already had a premature delivery or a late miscarriage, or you are expecting twins.

This can be done at any stage starting at week 16 of pregnancy, but is most helpful when done sequentially at week 17 and 21 of pregnancy.

The most accurate way to obtain cervical length is through transvaginal ultrasound. So, an empty bladder is required for this scan.

A cervical scan typically takes around 30 – 45 minutes.

Generally, the cervical length should be more than 25 mm. If we find out you have a shortened cervix in your first appointment, we may recommend you to have a rescan in 2 to 3 weeks. If your cervix is consistently less than 25 mm, your doctor may advise you to take progesterone or to insert a cervical cerclage.

This scan is done transvaginally by our accredited sonographers, and it will not pose any harm to your baby or your pregnancy.

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