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First-trimester dating scan, 11-13+6 weeks - accurate dating and combined trisomy screening.

Performed at 11 weeks + 2 days to 13 weeks + 6 days, the first-trimester dating scan measures the fetal crown-rump length (CRL) to accurately date the pregnancy, and - when the parents choose - combines nuchal translucency (NT) with maternal PAPP-A and β-hCG for combined trisomy 21/18/13 screening.

A fetal-medicine sonographer performing a first-trimester dating scan in a private London clinic

Indicative pricing

What a private first-trimester dating scan costs in London.

Indicative ranges across UK private providers.

In short

£180–£320, with dating and viability confirmed the same visit.

Scan type Indicative range
Standard first-trimester dating scan £180–£320
Dating scan + nuchal translucency £220–£380
Combined trisomy screening (NT + PAPP-A + β-hCG) £300–£500
Combined screening + fetal-medicine consult £500–£850
Non-invasive prenatal test (NIPT) add-on £400–£650
Urgent same-week appointment £350–£600

Prices vary by clinic, whether nuchal translucency and combined biochemistry are added, and whether a same-visit fetal-medicine consultation is included.

The problem

A first-trimester scan is only as good as who measures the NT.

Nuchal translucency has to be measured to Fetal Medicine Foundation criteria to be valid - a millimetre matters. We route you to an FMF-certified fetal-medicine sonographer, not a generalist.

  • Want the full combined screen?

    FMF-standard NT plus PAPP-A and β-hCG, with a single risk figure returned within days.

  • Screening came back high risk?

    Same-week fetal-medicine consult, NIPT, or CVS pathway - the next step, not just the number.

What it shows

What a first-trimester dating scan answers.

The scan answers a set of specific questions - dating, viability, chorionicity, combined trisomy risk and major structural anomalies. These are the findings we most often report.

  • Accurate gestational-age dating

    CRL between 45-84 mm dates the pregnancy to within 3-5 days.

  • Nuchal translucency measurement

    Fluid at the back of the fetal neck, measured to FMF standards.

  • Combined trisomy 21/18/13 risk

    NT + PAPP-A + β-hCG + maternal age produces a single risk figure.

  • Multiple pregnancy (mono/di-chorionic)

    Confirms twins or more and determines chorionicity - critical for later care.

  • Early structural anomalies (major)

    Anencephaly, large abdominal-wall defects and other major structural findings.

  • Anembryonic pregnancy

    An empty gestational sac - a missed miscarriage picked up early.

  • Molar pregnancy

    The characteristic ultrasound appearance of gestational trophoblastic disease.

  • Red flag: NT > 3.5 mm - urgent fetal-medicine referral

    A markedly increased nuchal translucency warrants same-week fetal-medicine review.

Next steps

What can follow a first-trimester scan.

The scan is a fork in the road. These are the options - from reassurance to invasive testing and onward specialist care.

  • Reassurance if low risk

    A low combined risk with a normal early anatomy survey is powerful reassurance to carry into pregnancy.

  • Non-invasive prenatal testing (NIPT)

    A maternal blood test analysing cell-free fetal DNA - used contingent on an intermediate combined risk, or as a primary screen.

  • Chorionic villus sampling (CVS)

    A diagnostic test between 11 and 13 weeks - the answer when parents want certainty after a high-risk screen.

  • Amniocentesis (from 15 weeks)

    The alternative diagnostic test later in pregnancy, when CVS is no longer possible.

  • Anomaly scan at 20 weeks

    The definitive structural survey - every pregnancy should have one, regardless of first-trimester findings.

  • Maternal-fetal medicine referral

    A same-week consultant fetal-medicine review when the scan flags anything unusual.

  • Multi-disciplinary team review

    For complex findings, a joint fetal-medicine, obstetric and neonatal team meeting.

  • Postnatal paediatric planning

    Where a diagnosis is made, planning for delivery, neonatal care and long-term follow-up starts now.

Safety and red flags

One of the safest tests in medicine - with a few things to know.

Ultrasound is exceptionally safe in pregnancy. The practical points are what the scan can and cannot answer, and which findings need urgent onward care.

  • Painless, radiation-free

    A handheld probe and gel - no needles, no radiation, no contrast.

  • Warm gel used

    The contact gel is warmed, so the transabdominal scan is comfortable from the first touch.

  • Position on the couch

    You lie on your back with a moderately full bladder - that is the whole preparation.

  • Transvaginal is safe in pregnancy

    Where views are limited, a transvaginal scan is safe at this stage and quickly gets the answer.

  • Screening, not diagnosis

    The combined test gives a risk figure - a high risk is not a diagnosis, and needs NIPT or CVS to confirm.

  • Anti-D planning in RhD-negative women

    If invasive testing follows, RhD status guides anti-D prophylaxis - we flag this to the fetal-medicine team.

  • A normal scan is not a full clear

    The anomaly scan at 20 weeks is the definitive structural survey - first-trimester ultrasound catches only major findings.

  • NIPT sometimes a follow-on

    For borderline or intermediate combined risk, NIPT is often the next step before considering invasive testing.

  • Bring dating and prior imaging

    Your LMP date, any prior scan and - for repeat pregnancies - previous obstetric history materially sharpen the report.

  • NT > 3.5 mm
  • Suspected structural anomaly
  • Molar pregnancy
  • Missed miscarriage
  • Ectopic pregnancy
  • Monochorionic multiples with size discordance
  • High combined risk (> 1:150)
  • Reduced fetal movement (later)
  • Placenta praevia / vasa praevia flag

Reading your report

A first-trimester report can look intimidating. It isn’t.

Whatever the finding, the report keeps to the same four parts.

A consultant fetal-medicine sonographer reviewing first-trimester ultrasound images on a clinical workstation, London

A quiet reminder

The report is written for your obstetrician, not for you - and that’s normal.

If you would like us to talk you through it before your follow-up, just ask.

  1. 01 Header

    Indication and gestational age

    Your details, the reason for the scan, LMP-based gestational age and the scan gestation.

  2. 02 Technique

    Transabdominal and transvaginal views

    Which approach was used, image quality, and whether views met FMF criteria for NT.

  3. 03 Findings

    CRL, NT, biochemistry, anatomy survey

    Crown-rump length, nuchal translucency, PAPP-A and β-hCG values, and the early anatomy survey.

  4. 04 Impression

    The conclusion: read this first

    Dating, viability, chorionicity, combined risk figure and the concrete next step - read this first.

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Frequently asked

Everything we get asked about the first-trimester dating scan.

Quick answers on cost, timing, NT vs NIPT, and when CVS or amniocentesis come in.

  • What does a first-trimester dating scan show?

    It confirms the pregnancy is in the uterus and viable, dates it accurately using crown-rump length (CRL), and - when parents choose - combines nuchal translucency with maternal PAPP-A and β-hCG to give a single combined risk for trisomy 21, 18 and 13. It also detects the most major structural anomalies and confirms singleton or multiple pregnancy.

  • When should the scan be done?

    The window is 11 weeks + 2 days to 13 weeks + 6 days - CRL between 45 mm and 84 mm. Outside that window the combined risk calculation is invalid, and dating is done from second-trimester biometry instead.

  • What is nuchal translucency?

    A small pocket of fluid at the back of the fetal neck. All fetuses have some - the measurement, when combined with maternal blood biochemistry and age, adjusts the background risk for trisomy 21, 18 and 13. An NT above 3.5 mm warrants urgent fetal-medicine referral regardless of the combined risk figure.

  • Is combined screening the same as NIPT?

    No. Combined screening uses ultrasound plus a maternal blood test to produce a risk. NIPT (non-invasive prenatal testing) analyses cell-free fetal DNA in a maternal blood sample and is more accurate - but still a screen, not a diagnosis. Diagnosis requires CVS or amniocentesis.

  • When would I need CVS or amniocentesis?

    When screening returns a high risk - typically > 1:150 on combined screening, or a high-risk NIPT - and the parents want a definitive answer. CVS is performed at 11-13 weeks; amniocentesis from 15 weeks.

Sources

Published 2026-07-30 · Reviewed by Pulse Atlas Editorial Board, · Next review 2027-07-30 · Reading time ~5 min

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In practice, in London

Where first trimester dating scan sits in a private London pathway

With first trimester dating scan, the London question is usually about report turnaround and the radiologist reading it - not whether the scan is available. On the NHS, first trimester dating scan typically sits behind a triage step and a wait that can stretch from a few weeks into months. In London’s private sector, the same appointment often lands within days. That speed matters when symptoms are disrupting work, sleep, or a plan you’d already committed to - and it’s the single most common reason people call us in the first place.

A private first trimester dating scan pathway in London usually looks like this: an initial consultation, any diagnostics booked at a nearby facility (most within Zone 1 or 2), and a written report sent to you and your GP within a few days. The consultants we work with hold NHS posts alongside their private lists, which keeps the standards consistent across both settings. For first trimester dating scan specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.

The value is knowing which consultant reads this particular presentation best, which unit turns reports around fastest, and which pathway won’t hit a dead end if the findings point somewhere unexpected.