How effective is nuchal translucency scan for Down syndrome?

During an early pregnancy ultrasound, the clinician measures the fluid at the back of the baby’s neck. That measurement is considered alongside the pregnancy stage and other screening information. A thicker measurement can be associated with Down syndrome and some other chromosomal or structural conditions, but it can also occur when the baby does not have one of these conditions.

A result described as higher chance is a reason to discuss follow-up, not a diagnosis. A lower-chance result reduces concern but cannot rule out every condition. Screening and diagnostic tests answer different questions.

Ask the maternity team to explain the result in the context of your complete screening assessment. Depending on the result and your preferences, they may discuss another screening option or a diagnostic test that examines fetal chromosomes more directly. Diagnostic testing can provide clearer information, but it also has its own considerations.

Keep the scan report and note whether the measurement was obtained within the recommended pregnancy window. If the view was limited or the timing was unsuitable, the team may suggest another assessment. Genetic counselling can help you understand choices without pressure.

Contact your maternity service promptly if you have heavy bleeding, severe abdominal pain, fluid loss, fainting, or feel acutely unwell after an appointment. These symptoms need assessment because they relate to pregnancy wellbeing, not because they confirm Down syndrome.

For questions about a scan result, arrange a review with your obstetric or fetal-medicine team soon, especially if follow-up testing was recommended or you are unsure when it should happen.

Ask: What does my result mean in the full screening context? Was the measurement clear and taken at the appropriate stage? What follow-up tests are available, and what would each test tell me? When should I expect the next appointment?