Assessment of fetal breathing movements using three different ultrasound modalities.

Twenty-five consecutive women in the third trimester of pregnancy were studied to determine the presence or absence of fetal breathing movements using three different ultrasound imaging techniques. Using real-time B-mode observation of the fetal trunk as the standard, image-directed pulsed wave Doppler insonation of the umbilical vein confirmed the presence of breathing movements with a sensitivity of 100% and the absence of breathing movements with a specificity of 100%. The sensitivity and specificity of color Doppler imaging of the fetal naso- and oropharynx for the presence or absence of fetal breathing movements were 96% and 100%, respectively. In the current study, the detection of fetal breathing movements by three different ultrasound modalities was virtually interchangeable.