10 Week Scan

A 10 Week Scan is a detailed ultrasound examination performed at around 10 weeks of pregnancy to assess the baby’s early development. Although the fetus is still very small, many important structures can already be seen, including the early brain, spine, abdominal wall, limbs and heart position. In our view, with modern high-resolution ultrasound and advanced NIPT, the 10 Week Scan has the potential to become the main early screening scan and may eventually replace the traditional 12–13-week screening scan. At present, however, a targeted follow-up scan at 12–13 weeks remains important in selected cases, especially when NT is increased or early anatomy is not completely reassuring.

The 10 Week Scan is different from the standard 12 Week Scan because it is performed earlier, usually by transvaginal ultrasound, which can provide higher resolution than a standard 12-week transabdominal scan. This allows very detailed assessment of early fetal anatomy, including the brain, spine, abdominal wall, limbs, heart position and NT, at a stage when many important developmental features can already be seen. In our experience, 10 weeks is also the best time to use diagnostic 3D ultrasound, as the fetus is small enough to acquire high-quality 3D volumes for detailed review and audit. Currently the 12 Week Scan remains standard first-trimester ultrasound, but the 10 Week Scan can provide earlier reassurance, earlier detection of significant problems and better integration with NIPT.

At the 10 Week Scan, many key fetal structures can already be assessed reliably, especially when high-resolution transvaginal ultrasound and 3D imaging are used. This includes the early brain, skull, spine, abdominal wall, stomach, bladder, cord insertion, limbs, hands and feet, fetal movements, heart position and basic cardiac activity. NT can also be assessed at this stage and is one of the most important early markers of fetal health. Some structures are still very small or immature, so the 10 Week Scan should be seen as an early detailed assessment rather than a complete replacement for all later anatomical checks.

At the 10 Week Scan, we can potentially detect a range of major structural abnormalities, particularly those affecting the brain, skull, spine, abdominal wall, limbs, bladder and early heart position. Examples include severe brain (alobar holoprosencephaly)and skull (acrania) abnormalities, major spinal defects, large abdominal wall defects, abnormal limb development, severe bladder enlargement, increased NT, early hydrops and some major cardiac or body-position abnormalities. The scan can also identify findings that may suggest a higher risk of genetic or syndromic conditions, even when NIPT is low risk. However, understandably not all abnormalities are visible at 10 weeks, and some develop or become clearer later in pregnancy, so follow-up imaging is strongly recommended.

The best approach is to use both — starting with a transabdominal scan (TAS) and then offering a transvaginal scan (TVS) for a more detailed assessment.
We begin with TAS. No full bladder is needed, and in most cases TAS provides excellent diagnostic images to confirm the number of babies, document the heartbeat, observe fetal movements, and measure the crown–rump length (CRL). In many pregnancies, TAS is also preferred for measuring the NT at 10 weeks because, due to gravity, the baby often lies on its back, which can make the mid-sagittal view easier to obtain.
TAS can give a useful overview of early fetal anatomy, but a precise, structured assessment of fetal structures at 10 weeks is usually better with TVS. Once we have obtained as much information as possible abdominally, we offer TVS. In our experience, most patients choose to proceed, as TVS typically provides the highest-resolution views for early anatomy and can also help with NT measurement when the fetal position is optimal.
If the baby’s position is not suitable for a direct NT measurement (for example, an oblique or coronal view), there is also the option of using a reconstructed 3D dataset to obtain an accurate measurement.

The main limitation of the 10 Week Scan is that the fetus is still very small and some organs are not yet fully developed or easy to assess. Even with high-resolution transvaginal ultrasound and 3D imaging, not every abnormality can be seen at this stage. Some problems, especially more subtle heart, brain, kidney, facial, skeletal or growth-related abnormalities, may only become visible later in pregnancy. Image quality can also be affected by fetal position, maternal anatomy, fibroids, bleeding, or technical factors. Therefore, a normal 10 Week Scan is very reassuring, but it cannot guarantee that the baby has no structural or genetic condition, and follow-up scans are needed.

High-resolution ultrasound is especially important at 10 weeks because the fetus is still very small and even tiny anatomical details matter. Better image resolution allows the sonographer to see early structures more clearly, measure NT more accurately and identify subtle findings that may be missed with lower-quality imaging. Transvaginal ultrasound often provides excellent resolution at this stage, and diagnostic 3D can also be very helpful for reviewing the fetal anatomy in detail. Without high-resolution equipment and specialist experience, a 10 Week Scan can easily become unreliable or falsely reassuring.

The 10 Week Scan and NIPT work very well together because they check different things. NIPT is highly effective for screening the most common chromosomal conditions, such as Down syndrome, Edwards syndrome and Patau syndrome, but it cannot assess the baby’s anatomy. The 10 Week Scan adds an early structural assessment, including NT, brain, spine, abdominal wall, limbs, early heart position and other key developmental features. This means that NIPT can provide powerful genetic screening, while the scan can identify structural findings or increased NT that may suggest the need for extended NIPT, diagnostic testing or targeted follow-up imaging. Together, they give earlier and broader information than either test alone.

Yes. NIPT is excellent for screening selected chromosomal conditions, especially Down syndrome, Edwards syndrome and Patau syndrome, but it cannot examine the baby’s anatomy. American College of Obstetricians and Gynecologists specifically notes that structural defects may occur with or without aneuploidy, which is why ultrasound assessment remains important even when cfDNA/NIPT is low risk.

The 10 Week Scan can potentially detect problems that NIPT may miss, such as major brain or skull abnormalities, spinal defects, abdominal wall defects, limb abnormalities, abnormal early heart position, hydrops and increased NT. Some of these findings may also be early signs of genetic or monogenic conditions that are not covered by basic NIPT panels. NHS Genomics also states that NIPT is not designed to detect fetal genetic conditions outside the targeted aneuploidies.

So, the 10 Week Scan and NIPT are best seen as complementary tests: NIPT assesses selected genetic risks, while the scan assesses early fetal anatomy and markers of fetal health.

If something abnormal is suspected at the 10 Week Scan, we will explain the finding clearly, discuss what it may mean, and usually recommend a planned follow-up rather than making conclusions from one early scan alone. Depending on the finding, this may include extended NIPT, diagnostic testing such as CVS, or a targeted scan at 12–13 weeks to reassess the anatomy, NT and early heart development. In some cases, further specialist scans may also be arranged later in pregnancy, including a detailed anomaly scan and fetal heart scan. The aim is to give you earlier information, reduce uncertainty where possible, and create a clear, individual plan for the next steps.

A targeted follow-up scan at 12–13 weeks is often recommended because some structures become clearer as the baby grows, and some findings seen at 10 weeks need to be confirmed or reassessed. This scan allows us to review the NT, check whether any early concern has resolved, progressed or become more specific, and examine the anatomy in more detail, including the brain, spine, abdominal wall, limbs and early heart development. It is especially important when NT was increased, the 10 Week Scan was technically limited, or any structural concern was suspected. The aim is not simply to repeat the scan, but to use the extra development between 10 and 12–13 weeks to make the assessment more precise and guide the next steps.

A reliable 10 Week Scan should be performed by a specialist who is experienced in early fetal anatomy, high-resolution transvaginal ultrasound and first-trimester diagnosis. The fetus is very small at 10 weeks, so the scan requires excellent image optimisation, careful use of magnification, understanding of normal 10-week anatomy, and awareness of which structures can and cannot be assessed at this stage.

Experience with NT measurement at 10 weeks is particularly important, because the technique and interpretation are not the same as in the standard 11–13-week window. The sonographer also needs to recognise early signs of major structural problems, know when a finding is likely to be normal developmental variation, and understand when targeted follow-up or genetic testing should be recommended.

In addition, good practice should include ongoing audit, image review, peer feedback and correlation with 12–13-week and later pregnancy outcomes. In our view, the 10 Week Scan should not be treated as a routine “quick look” scan, but as a specialist early fetal assessment requiring appropriate training, equipment and quality assurance.