Second trimester · 16 to 24 weeks · Sevenoaks, Kent
Cervical Length Scan (16–24 Weeks)
A consultant-led scan that measures the length of your cervix, the neck of the womb, to assess your risk of late miscarriage and preterm birth. If your cervix is shorter than expected, early detection means monitoring and treatment can start in good time.
- Consultant-led scan from 16 weeks
- Accurate transvaginal measurement
- Clear results and a personalised plan
Medically reviewed by Professor Ranjit Akolekar, MBBS, MD (Res), MRCOG, Consultant in Fetal Medicine and Obstetrics · Last reviewed October 2026
Cervical length scan £100
An accurate measurement of your cervix, interpreted by a consultant in fetal medicine. Your scan includes:
- Consultant-led transvaginal ultrasound
- Accurate measurement of your cervical length
- Your results explained during your appointment
- A written report of your results
Cervical length · © The Pregnancy Clinic
Why cervical length matters
One of the most useful ways to assess the risk of preterm birth.
The cervix in pregnancy
The cervix is the neck of the womb. In a healthy pregnancy it stays long and closed, supporting your pregnancy until your baby is ready to be born.
Early shortening
In some pregnancies the cervix shortens earlier than expected, often without any symptoms. In general, the shorter the cervix, the higher the chance of late miscarriage or preterm birth.
Timely treatment
When a short cervix is found early, treatments such as progesterone or a cervical stitch can be offered, which can reduce the risk of preterm birth.
Safe and accurate
A transvaginal scan gives the clearest, most reliable measurement. It is safe for you and your baby, and does not increase the risk of miscarriage, infection or preterm labour.
Most cervical length scans are reassuring. Identifying the risk of preterm birth early is an important part of comprehensive antenatal care.
Who should have a cervical length scan
Helpful in every pregnancy, and particularly important if you have risk factors.
Especially important if you have had
- A previous late miscarriage or preterm birth
- Previous treatment to the cervix, such as LLETZ for an abnormal smear
- A short cervix in a previous pregnancy
- An unusually shaped womb, such as a bicornuate uterus
- A caesarean birth at full dilation in a previous pregnancy
Cervical shortening can also happen in women with no obvious risk factors.
When the scan is done
- Between 16 and 24 weeks, the best time to identify early shortening
- From around 14–16 weeks if you have risk factors, repeated every 2 weeks until 24 weeks
- At around 20–22 weeks if you have no risk factors, often alongside your anatomy scan
- At this stage, a cervical length of more than 25 mm is reassuring
If your cervix is short
Expert, unhurried support from a fetal medicine specialist.
If your cervix is shorter than expected, your consultant will explain what this means for you and discuss your options in detail. Depending on your situation, these may include:
- Closer monitoring with repeat cervical length scans
- Treatment with vaginal progesterone
- Consideration of a cervical stitch (cerclage)
- A clear plan, shared with your NHS maternity team
- A second opinion consultation + scan if you have had a concerning result elsewhere
A short cervix does not mean your baby will come early
It means the chance of preterm birth is higher. Many women with a short cervix go on to have healthy pregnancies and give birth at or near term, with the right monitoring and treatment.
Whatever your result, you will leave your appointment with a clear explanation and a personalised plan for the rest of your pregnancy.
Your cervical length scan appointment
Private, unhurried and explained as we go.
Before your scan
No special preparation is needed, though an empty bladder makes the scan more comfortable. Please bring your maternity notes and any previous scan reports.
During your scan
A small, gentle probe is placed into the vagina to give a clear, accurate measurement. It takes only a few minutes and should not be painful.
After your scan
Your consultant explains your result and, if any follow-up or treatment is needed, agrees a personalised plan with you.
Your scan journey
Where the cervical length scan fits in your pregnancy.
Prefer everything planned for you? See our scan packages →
Why families trust us
Consultant-led care, recommended by our patients.
Led by Professor Ranjit Akolekar, Consultant in Fetal Medicine and Obstetrics, with over 25 years’ experience in high-risk pregnancy and more than 250 published studies. Read more →
What our patients say
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Health insurance and self-pay accepted · No GP referral needed
Cervical length scan: your questions answered
What is the cervix, and why is it assessed in pregnancy?
The cervix is the neck of the womb. In a healthy pregnancy it stays long and closed until labour approaches at term. In some pregnancies it shortens earlier than expected, which is linked with a higher chance of late miscarriage or preterm birth. If early shortening is found, treatments such as progesterone or a cervical stitch can be offered to reduce this risk.
What is a cervical length scan?
An ultrasound scan that measures the length of your cervix. The most accurate way to do this is with a transvaginal scan, where a small probe is gently placed into the vagina to give a clear and reliable measurement.
Is the scan done abdominally or internally?
Internally. An abdominal scan does not always give a clear view of the cervix and can lead to inaccurate measurements, so a transvaginal scan is recommended for assessing cervical length.
Is a transvaginal scan safe for my baby?
Yes. Transvaginal ultrasound is safe in pregnancy and does not increase the risk of miscarriage, infection or preterm labour.
When is the cervical length scan done?
Usually between 16 and 24 weeks, the best time to identify early shortening. If you have risk factors, monitoring may start from around 14–16 weeks and be repeated every 2 weeks until 24 weeks. Without risk factors, the scan is often done at around 20–22 weeks, alongside the anatomy scan.
Who should have a cervical length scan?
It can be offered to all women, and is particularly important if you have had a previous late miscarriage or preterm birth, treatment to the cervix such as LLETZ, a short cervix in a previous pregnancy, an unusually shaped womb, or a caesarean birth at full dilation. Cervical shortening can also happen in women with no obvious risk factors.
What is a normal cervical length?
Between 16 and 24 weeks, a cervical length of more than 25 mm is considered reassuring. In pregnancies that reach full term, the average cervical length is around 30–32 mm. In general, a longer cervix is more reassuring.
What happens if my cervix is shorter than expected?
Your options will be discussed in detail with your fetal medicine consultant. Depending on your situation, this may include closer monitoring, treatment with progesterone, or a cervical stitch.
Does a short cervix mean I will have my baby early?
No. It means the chance of preterm birth is higher, but many women with a short cervix go on to have healthy pregnancies and give birth at or near term, with the right monitoring and treatment.
Will I receive a clear plan after the scan?
Yes. Most cervical length scans are reassuring. Your result will be explained during your appointment, with time for your questions, and if any follow-up or treatment is needed, we will agree a personalised plan with you.
More answers in our pregnancy FAQs.
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