Fetal Heart Rate (FHR) during NT screening

Fetal Heart Rate (FHR) during

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The Role of Fetal Heart Rate (FHR) in NT Screening:Although NT screening primarily focuses on the measurement of the translucency layer, Fetal Heart Rate (FHR) is also recorded as a routine part of the ultrasound assessment. Here’s why FHR is important in this context-

1. Indicator of Fetal Well-Being:

Normal FHR Values: Typically, the normal range in the first trimester is between 120–160 beats per minute. A normal heart rate suggests proper cardiac function and overall fetal health.
Abnormal FHR: Deviations such as tachycardia (elevated FHR) or bradycardia (lower than normal FHR) can be indicators of potential fetal distress, congenital heart issues, or other underlying abnormalities.

2. Indicator of Fetal Well-Being:

Confirmation of Fetal Viability: Recording the fetal heart rate confirms that the fetus is alive and supports the accurate measurement of NT.
Guidance for Image Acquisition: A clear, consistent heart rate helps sonographers optimize the image quality and ensure that the measurements (including NT thickness) are taken when the fetus is in an optimal position.

3. Indicator of Fetal Well-Being:

While NT measurement is the main focus for chromosomal risk estimation, the inclusion of FHR provides additional physiological data. If there’s an abnormal heart rate along with an increased NT measurement, it may raise the suspicion for certain conditions (including cardiac anomalies) and prompt further investigation.

4. Indicator of Fetal Well-Being:

Research has evaluated the correlation between abnormal FHR parameters and increased NT thickness. Although FHR is not directly incorporated into the NT risk calculation algorithms, variations in FHR might reinforce the clinical decision-making process when NT measurements are on the borderline.

5. Measurement and Methodology:

Doppler Ultrasound: Utilizes the Doppler effect to detect the movement of blood in the fetal heart, providing an immediate reading of the FHR.
M-Mode Ultrasound: Offers a graphical representation of the heart motion over time, which helps in verifying the heart rate and rhythm.
The simultaneous recording of FHR and NT allows for a comprehensive assessment during the first-trimester scan. Proper ultrasound technique ensures the fetus is imaged in a neutral position without excessive movement, which is crucial for accurate NT measurement and reliable FHR determination.