13 Week Scan

The 13-week scan, also known as the nuchal translucency (NT) scan, is a pivotal milestone in early pregnancy assessment. This ultrasound serves as an initial screening for chromosomal abnormalities like Down syndrome, as well as other potential fetal anomalies.

The benefits of a scan at this stage include:

  • Highest detection rate of any “no risk” or screening test for chromosome
    abnormality (including Down syndrome)

  • Accurate dating of the pregnancy

  • Diagnosis of multiple pregnancies

  • Diagnosis of early pregnancy failure (at 12 weeks approximately 1 in 50
    women are found on ultrasound to have a failed pregnancy)

  • Detection of many physical abnormalities is possible with ultrasound at
    this stage

Why do I need a scan at 13 weeks?

It has been shown that a high proportion of fetuses with a chromosomal abnormality such as Down syndrome can be suspected at an ultrasound examination at 13 weeks. All fetuses at 13 weeks retain small amounts of fluid under the skin around the head and neck, but this is usually slightly increased when Down syndrome is present. This is not an “abnormality” because the fluid is absorbed during the pregnancy. Additional fluid therefore does no harm but can be used as a marker for Down syndrome.

Fluid under the skin looks black on ultrasound, and we measure the “nuchal translucency” or black area, when this area is thickened it is called “nuchal oedema” (or swelling behind the neck).

The scan allows for the early detection of structural abnormalities in the developing fetus, including those related to the heart, limbs, and other vital organs. This early detection can help healthcare providers plan for any necessary interventions or treatments.

This scan is also performed after the percept™ NIPT test to detect any physical abnormalities possible with ultrasound at this stage.

What can be seen?

During a 13-week scan, several key aspects of the developing fetus can be observed and assessed:

  1. Fetal Heartbeat and Viability: One of the earliest and most reassuring observations is the confirmation of a beating fetal heart. The presence of a strong heartbeat indicates the viability of the pregnancy and is a significant emotional moment for expectant parents.

  2. Nuchal Translucency Measurement: The nuchal translucency, a fluid-filled space at the back of the fetal neck, is measured to assess the risk of chromosomal abnormalities, particularly Down syndrome. An increased measurement might indicate a higher likelihood of certain genetic conditions.

  3. Structural Development of the Heart: The scan provides an opportunity to evaluate the structural development of the fetal heart. Early detection of any heart abnormalities or malformations allows for timely intervention or planning for specialized care.

  4. Limb and Organ Formation: The scan can reveal the initial development of the baby's arms and legs, as well as early structures in the head, chest, and abdomen. This assessment helps identify any potential anomalies or irregularities in these vital areas.

  5. Placental Location: The position of the developing placenta is assessed during the scan. An abnormal placement could have implications for the pregnancy's progression and the mode of delivery.

  6. Identification of Multiples: The scan can determine whether the pregnancy involves a single fetus or multiple fetuses. This information is crucial for managing the care and monitoring of the pregnancy.

  7. Uterine Concerns: The scan also images the mother's uterus and can help identify any potential issues, such as the presence of fibroids or other abnormalities that might impact the pregnancy.

FAQs

How is the scan performed?

For 9 out of 10 patients the measurements of the nuchal translucency can be carried out with a scan through the abdomen, so this will be the first part of the examination. If the measurement could be carried out better through an internal scan, then you would be offered this method (of course you are always free to refuse any examination you do not wish to have).

Having finished the scan through the abdomen most women will be offered an additional internal scan since this usually gives better images of the fetus.

What happens if the scan indicates a potential issue?

If the scan shows any concerning results, your healthcare provider will guide you on the next steps. This might involve further testing or consultations with specialists to determine the best course of action.

Will the scan be able to detect all possible problems?

While the scan is a valuable tool for early detection, it might not identify all potential issues. Some structural defects and abnormalities are identified later in pregnancy.

Additional scans and tests might be needed later in pregnancy to ensure a comprehensive assessment.

It is recommended that you also have a scan at 20 weeks to assess morphology and placental location.

How long does the scan usually take?

The scan typically takes around 30 minutes, depending on various factors such as the position of the fetus and the quality of the images obtained.

Anticipate around 90 minutes for the duration of your visit, although the actual duration is usually shorter. Unforeseen delays can occasionally occur.

If an issue arises during the routine ultrasound, it will be addressed immediately with the patient. Depending on the complexity and individual requirements, additional examination and assessment might extend the process by over an hour. We apologize for these unpredictable delays and strive to minimize inconvenience.

Can the sex of the baby be determined during this scan?

Generally, determining the baby's sex accurately at 13 weeks might be challenging. The primary focus is on assessing the baby's development and screening for abnormalities.

Can I bring someone with me to the scan?

We allow one adult support person, partner, or family member to accompany you during the scan.

For various reasons, we have policies in place that restrict children from attending ultrasound appointments. While it might be disappointing for families, Ultrasound appointments require a focused environment to obtain accurate diagnostic images, and having children present can sometimes cause distractions that might affect the quality of the examination.