Fetal Doppler 101: Everything You Need to Know About Fetal Dopplers

What is Fetal Doppler for?

A fetal Doppler is a kind of non-invasive medical apparatus used to check and measure the fetal heart rate (FHR) during expecting mothers’ gestation. Normally, a fetal Doppler uses a 3MHz or 2MHz probe to detect the fetal heart rate. The small device employs fetal diagnostic ultrasound to collect the fetal heartbeat signals and then converts the signal into fetal heart beat (embryocardia) that we can hear.

How many kinds of the Fetal Doppler probe are there?

There are two types of probe that are equipped with a fetal heart Doppler - 2MHz or 3MHz probes. While 3 MHz probe is more sensitive than 2MHz probe for most cases, 2MHz probe works better for overweight expecting mothers.

How many fetal heart monitoring devices are there?

Apart from the difference in probe frequency, the handheld fetal Dopplers can be divided into two types according to their functions, the regular one and the digital one. The only difference is that the digital Dopplers is equipped with an LCD screen displaying several parameters including FHR, probe type, battery indicator and different display modes altogether.

Besides, there are some other types of fetal heart monitoring devices, e.g. fetoscope, electronic fetal monitoring, telemetry monitoring, which belong to the fetal heartbeat detection big family.

What is FHR?

The normal range of fetal heart rate is between 120 - 180 BPM (Beats Per Minute). Generally, the fetal monitoring device produced by different manufacturers can detect the FHR range between 50 and 210BPM. But the readings of FHR may be fluctuated based on some reasons, for example, fetal movements.

How does the Fetal Doppler work?

The usage of the small device is very easy and simple. The handheld design allows users to hold the unit comfortably while checking unborn baby’s FHR. The best gesture for expecting mothers is to lie down and expose their abdomen. A certain amount of ultrasound gel is imperative for the FHR check. The important function of ultrasound gel is to reduce static that may be caused during the course of using a fetal Doppler. The fetal heart beat can be detected for as early as 8-12 weeks of pregnant women. Users can slowly adjust the angle of the probe when searching for the fetal heart beat. Users should be patient and careful when doing the exam. Since there is no evidence of harmful effects on expecting mothers by any scientific research and experiments, it should be safe to use ultrasonic Dopplers for expecting mothers and health care professionals to listen to baby’s heartbeat. And we recommend that each examination time should not exceed 10 minutes. If you have more questions or need further assistance when using this little device, please contact your health care provider for more help.


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