12-Week Ultrasound: What to Expect

Your 12-week ultrasound is meant to assess your baby's development at the end of the first trimester of your pregnancy. At week 12, the baby’s organs and body systems are formed, and you may actually be seeing your baby for the first time.

With this ultrasound, your healthcare provider may be able to establish your due date and confirm the number of developing fetuses. They may screen for conditions like Down syndrome or rule out an ectopic pregnancy.

This article talks about what to expect at your 12-week ultrasound, and why it's important with relatively no risks to you or your child. It also explains the types of ultrasound procedures, questions to ask, and ways to prepare for your appointment.

Purpose of a 12-Week Ultrasound

The 12-week ultrasound allows your healthcare provider to get a view of your baby inside the uterus. Ultrasound, or sonography, is an imaging method that uses the energy generated by sound waves to produce pictures of the inside of your body.

In many cases, an ultrasound is done in the first trimester to confirm pregnancy and the number of fetuses, as well as get a view of the baby’s overall development.

However, your ultrasound may not occur at exactly 12 weeks. Ultrasounds at 12 weeks are common but not standard, because not enough development has taken place at this stage for your healthcare provider to visualize your baby’s limbs and organs in detail.

Why Is It Important?

A 12-week ultrasound is done while you're still in an early stage of pregnancy and your healthcare provider will be limited in what they can see. But a 12-week ultrasound may be used to:

• Estimate your gestational age and due date
• Screen for certain disorders, such as Down syndrome
• Count the number of fetuses
• Check your baby’s heart rate
• Rule out an ectopic pregnancy (when a fertilized egg implants outside of the uterus)

While most women usually have two ultrasounds—one around 12 weeks gestation, and one around 20 weeks—your healthcare provider may perform just one. If only one ultrasound is performed, it will take place at around 20 weeks to:

• Check the fetal position, movement, and heart rate
• Estimate your baby’s size and weight
• Check the amount of amniotic fluid in the uterus
• Find the location of the placenta
• Confirm the number of fetuses
• Assess for abnormalities or birth defects

Nuchal Translucency Ultrasound Screening

The screening test for Down syndrome and two chromosomal disorders, trisomy 13 and trisomy 18, used at this stage of pregnancy is called a combined test. It involves a blood test and a test to measure fluid at the back of the baby’s neck (nuchal translucency) with an ultrasound scan.

However, combined screening is not a diagnostic test, which means it cannot tell you whether your baby has Down syndrome, trisomy 13, or trisomy 18. Instead, the screening provides a probability that the baby might have one of these genetic disorders.

The probability, or chance, is based on three criteria. They are:

• Your age
• Information obtained on an ultrasound
• Bloodwork results

The screening results can either alert you and your healthcare provider to an increased risk for one of these chromosomal disorders, or reassure you that your baby is at a lower risk for them.

A positive result that shows an increased risk does not mean that your baby has a problem, and a negative or normal result (one that shows a decreased risk) does not mean that the baby will not have a chromosomal abnormality.

What Happens During the 12-Week Ultrasound?

Your healthcare provider will likely perform a transabdominal ultrasound, which transmits waves through your abdomen. In some cases, a transvaginal ultrasound may be performed to capture more direct or detailed images. A scan usually takes 20 to 30 minutes to complete.

Transabdominal Ultrasound

During a transabdominal ultrasound, you will be asked to lie down on an exam table—either in a procedure room or your healthcare provider's office—with your abdomen exposed from your ribs to your hips. You may be asked to arrive to your appointment with a full bladder, which will create a window to the womb area.

When the test is ready to begin, your healthcare provider will apply an ultrasound gel to help conduct the sound waves to your skin. This will help improve the quality of the images produced by the ultrasound.

Your healthcare provider will then move a handheld ultrasound transducer back and forth across your abdomen using a small amount of pressure. This should not be painful, although you may experience some discomfort related to positioning.

They may pause over certain areas of your abdomen to capture specific images or measurements. Measurements will be taken from different sections of the baby’s body and your uterus. A short recording may be captured of your baby’s heart movement.

Transvaginal Ultrasound

During a transvaginal ultrasound, you will be asked to undress from the waist down, or you may even be asked to remove your clothing and wear a hospital gown. Unlike the transabdominal ultrasound, you will be asked to empty your bladder before the test begins.

When you are ready to begin the test, you will be asked to lie down on an exam table with your feet in stirrups, much like you would for a pelvic exam.

A wand-shaped transducer covered in a protective sheath will be inserted through the vagina for an internal view of the uterus. This should not be painful, but you may feel discomfort as you would during a pelvic exam.

Additional Ultrasounds

While the above describes a standard 12-week or first-trimester ultrasound, there may be reasons for your healthcare provider to request additional scans.

If you experience bleeding or other concerning symptoms, your healthcare provider may order a limited ultrasound to quickly check for a specific issue. This could occur at any point during your pregnancy.

You may also be asked to undergo a specialized ultrasound or have more regular scans performed. These ultrasound scans are conducted in the same manner as the 12-week ultrasound, but may examine the fetus in closer detail, with three-dimensional imaging.