Reassurance through your pregnancy
Preterm birth, a serious complication in pregnancy occurs in 6-8% of women. The risk of spontaneous preterm birth increases as the length of the cervix (neck of the womb) decreases.
About Cervical Length
Ultrasound scanning may be used to assess the length of the cervix in women at high risk of preterm birth. We will recommend an assessment after 16 weeks in high risk pregnancies. There is no proven benefit in assessing the cervix by ultrasound in women with no risk factors for preterm birth.
Women at high risk or preterm birth include:
- Prior very preterm birth (<32 weeks gestation)
- Previous cervical surgery (eg. cervical cone biopsy)
- Women with a cervical suture
- Women with suspected cervical incompetence
- Multiple pregnancies
What is a normal cervical length in pregnancy?
- At 20 weeks gestation the average cervical length is 40mm
- At 34 weeks gestation the average cervical length is 34 mm
The Cervical Length scan
We measure the cervical length by performing a simple trans-vaginal ultrasound examination is required to accurately measure the length of the cervix. We check for the following:
- Length of the cervix (normally >25mm)
- Funneling of the membranes at the internal os.
- Dilatation of the cervix
- Location of a cervical suture (if present)
The Cervical Length Scan results
If you are found to have a cervix which is shortened or dilated we will liaise with your healthcare team and your hospital letting them know our findings and provide them with a report, we will also organise any follow-up appointments you may it be needed.