Respiratory Distress and Elective Cesarean Section at Term

The main pulmonary artery will be seen between the pulmonary valve and the bifurcation of the right and left branches. The pulsed Doppler sample gate will be adjusted to 3 mm, and the angle of insonation will be kept at or around 15°. Doppler gain and scale will be tailored for optimizing the velocity waveform display, clearly showing the peak systolic velocity (PSV) and early diastolic notch. The MPA Doppler waveform will show a sharp systolic peak blood flow with a needle-like appearance. After the optimum fetal main pulmonary artery waveform, Doppler velocity will be manually traced three times, and the average will be taken.