Source:http://linkedlifedata.com/resource/umls/id/C0180844
UMD: Detectors designed to provide audible and/or or visual information about the fetal heart status by indirect measurements from the surface of the maternal abdomen. These devices can detect fetal heartbeats early in pregnancy. Fetal heart detectors may use ultrasonic, electrocardiographic, or phonocardiographic techniques; some detectors are capable of measuring the fetal heart rate.