Doppler fetal monitor

Invented in 1958 by Dr. Edward H. Hon, a Doppler fetal monitor or Doppler fetal heart rate monitor is a hand-held ultrasound transducer used to detect the fetal heartbeat for prenatal care. It uses the Doppler effect to provide an audible simulation of the heart beat. Some models also display the heart rate in beats per minute (BPM). Use of this monitor is sometimes known as Doppler auscultation. Doppler fetal monitors are commonly referred to simply as "Dopplers" or "Fetal Dopplers".