Pulmonary artery diameters in healthy fetuses from 19 to 40 weeks' gestation.

Objective: The purpose of this study was to construct nomograms for diameters of the fetal main pulmonary artery (MPA), right pulmonary artery (RPA), and left pulmonary artery (LPA) according to gestational age (GA) and estimated fetal weight (EFW).

Methods: Between May 2005 and February 2006, MPA and branch artery diameters were prospectively estimated with ultrasonography in 220 healthy fetuses from 19 to 40 weeks' gestation and correlated with GA and EFW.

Results: Mean MPA, RPA, and LPA diameters ranged from 2.93, 1.71, and 1.66 mm, respectively, at 19 weeks to 9.23, 5.49, and 5.65 mm at 40 weeks. Linear regression yielded the following formulas for the expected diameters according to GA: MPA=-2.77 + 0.30 x GA; RPA=-1.71 + 0.18 x GA; and LPA=-1.95 + 0.19 x GA. The following formulas were obtained by logarithm distribution for the expected diameters according to EFW: MPA=-1.165 + 0.247 x log of estimated fetal weight (lnFW); RPA=-0.651 + 0.141 x lnFW; and LPA=-0.718 + 0.150 x lnFW.

Conclusions: Nomograms of MPA and branch pulmonary artery diameters according to GA and EFW have been described, generating reference values.