12 Week Scan: What It Checks, What to Expect and What It Can Show

The 12-week scan, also known as the first trimester scan or dating scan, is one of the most important early pregnancy milestones. It provides reassurance, checks your baby’s early development and gives essential clinical information that guides pregnancy care.

This guide explains what the 12-week scan involves, what it checks for and how it helps your obstetric team monitor your pregnancy safely.

What Is the 12 Week Scan?

The 12-week scan is an ultrasound performed between 11 weeks and 13 weeks + 6 days of pregnancy.It is one of the key scans in early prenatal care and is recommended for all pregnant women.

The scan is usually performed abdominally (on your tummy), although some women may need a transvaginal scan if views are unclear.

What the 12 Week Scan Checks

The first trimester scan assesses several important areas:

• Confirms the pregnancy is viable

• Checks the baby’s heartbeat

• Confirms the number of babies (single or twins)

• Provides accurate dating of the pregnancy

• Assesses early development and major structures

• Measures nuchal translucency (NT)

• Helps assess the risk of chromosomal conditions such as Down syndrome

• Contributes to evaluating the risk of developing high blood pressure in pregnancy

• Checks the uterus, ovaries and surrounding structures

This scan provides your first detailed look at your baby’s early growth.

Nuchal Translucency (NT) Measurement

One of the most important parts of the 12-week scan is the NT measurement.This is a small pocket of fluid behind the baby’s neck. Measuring it helps:

• Estimate the risk of chromosomal conditions (including Down syndrome, Edwards syndrome and Patau’s syndrome)

• Inform whether further screening or diagnostic tests may be helpful

• Contribute to first trimester combined screening if you choose that option

Nuchal translucency is a screening tool, not a diagnosis. Your clinician will discuss results and next steps if further tests are recommended.

What the Scan Can Show at 12 Weeks

By 12 weeks your baby is more developed than many parents expect. The scan may show:

• Baby’s head, brain structures and skull

• The spine

• Arms, legs, hands and feet

• Early facial profile

• Stomach, bladder and abdominal wall

• Placental location

• Umbilical cord insertion

It also checks for early signs of conditions that may benefit from closer monitoring later in pregnancy.

What Happens During the Scan

The 12-week scan typically takes 20–30 minutes.

Here’s what to expect:

• Gel is applied to your abdomen

• The sonographer takes multiple measurements

• You will see the baby on the screen in real time

• Images and measurements are recorded

• You may receive printed or digital pictures

The scan is painless and safe, with no radiation.

Do I Need to Prepare for a 12 Week Scan?

You may be asked to arrive with a comfortably full bladder, which can help improve image clarity early in pregnancy. Your clinic will advise you if this is needed. You do not need to fast or stop any medication.

When Further Tests Are Recommended

Sometimes the 12-week scan suggests that further investigation might be helpful, such as:

• Non-invasive prenatal testing (NIPT)

• Additional ultrasound scans

• Diagnostic tests (CVS or amniocentesis), if recommended

Your obstetrician will explain any findings, what they mean and the options available.

When to Contact Your Obstetric Team

Reach out if you experience:

• Severe abdominal pain

• Heavy bleeding

• Persistent one-sided pain

• Concerns about pregnancy symptoms

• Anxiety about scan results

Your clinician will guide you and arrange assessment if needed.

Frequently Asked Questions

What is the 12 week scan?

It is an early pregnancy ultrasound performed between 11 and 13+6 weeks to check early development, confirm dating and measure nuchal translucency.

What does the 12 week scan check for?

It checks viability, development, major structures, NT measurement and early risk factors for chromosomal conditions and high blood pressure in pregnancy.

Is the 12 week scan internal or abdominal?

Most scans are abdominal. A transvaginal scan may be used if images are not clear.

Do I need to fast before a 12 week scan?

No. You may be asked to have a comfortably full bladder to improve visibility.

Can the 12 week scan detect abnormalities?

It can detect some early structural differences and markers, but detailed anatomical assessment occurs at the 20-week anomaly scan.