Reference ranges of Doppler parameters of foetal pulmonary artery segments between 19 and 39 weeks of gestation.

OBJECTIVE: To determine reference ranges of Doppler parameters of foetal pulmonary artery segments. METHODS: A prospective cross-sectional study was conducted to evaluate 150 healthy singleton pregnancies between 19 and 39 weeks of gestation. The proximal, middle and distal segments of the foetal pulmonary artery were assessed. The following Doppler parameters were evaluated: pulsatility index (PI) and peak systolic velocity (PSV). The mean, standard deviation (SD) and maximum and minimum values were determined for each Doppler parameter. Pearson's correlation coefficient (r) was used to assess the correlation between the foetal pulmonary artery segments. Polynomial regression was performed, and adjustments were made using the coefficient of determination (R(2)). RESULTS: The mean PI values (mean ± SD) in the proximal, middle and distal arterial segments were 2.99 ± 0.61, 2.25 ± 0.96 and 1.31 ± 0.58, respectively. The mean PSVs in the proximal, middle and distal segments were 50.68 ± 16.63, 24.396 ± 11.86 and 12.08 ± 3.66 cm/s, respectively. Significant differences were observed between the PI and PSV values from the different segments (p < 0.0001). A correlation between each Doppler parameter and gestational age was observed, and it was better represented using linear equations. CONCLUSION: We successfully determined the reference ranges for Doppler parameters of foetal pulmonary artery segments between 19 and 39 weeks of gestation.