At what gestational age is the nuchal translucency measurement typically performed?

• A. 11 to 14 weeks
• B. 8 to 10 weeks
• C. 15 to 20 weeks
• D. 20 to 24 weeks

Answer: (A)

The nuchal translucency measurement is typically performed between 11 to 14 weeks of gestation. This specific timeframe is critical for accurately assessing the risk of chromosomal abnormalities, such as Down syndrome. At this stage, the nuchal translucency, which is the fluid-filled space at the back of the fetus's neck, is measurable and correlates with the fetus's risk for certain genetic conditions.

Performing this measurement too early, such as at 8 to 10 weeks, would not yield reliable or comparable results, as the anatomy may not be fully developed and the nuchal fold may be too small to measure accurately. Conversely, measurements taken later in the pregnancy, such as between 15 to 20 weeks or 20 to 24 weeks, fall outside the optimal window and are less effective for first-trimester screening purposes. Thus, the 11 to 14 week window is deemed the appropriate period for this important diagnostic measurement.