Doppler Ultrasound in Obstetrics

Since its first description in 1964, Doppler-principle ultrasound has been used for detection of fetal life, placental localization, and more recently detection of multiple pregnancies and fetal heart monitoring. Techniques and methods of interpretation as applied to 521 patients gave the following accuracy in each determined: detection of fetal life (single examination, 98.8%; double examination, 100%); placental localization for placenta praevia, 96%, and diagnosis of multiple pregnancies, 99.7%. Two limitations of these techniques are (1) the fetal heart is not heard prior to 10 to 12 weeks gestation, and (2) experience is the key factor in placental localization, and thus it must be carried out by only one or two well-trained individuals in each hospital unit. On the other hand, accuracy, safety, and simplicity of the Doppler-principle ultrasound techniques far outweigh the limitations.