Reference Intervals of Fetal Cardiac Volume Between 14 and 40 Weeks of Gestation

Objectives To construct the reference intervals for the cardiac volume (CV) of normal fetuses between 14 and 40 weeks of pregnancy. Methods Low risk singleton pregnancies with normal fetuses were prospectively recruited to acquire 4D-cardio-spatiotemporal image correlation volume datasets (VDS). Subsequent off-line analyses of VDS were anonymously performed to calculate CV using the Virtual Organ Computer-aided AnaLysis technique. The reference intervals were established as a function of gestational age (GA), biparietal diameter (BPD), head circumference (HC), and estimated fetal weight (EFW) based on the best-fitted models for both mean and standard deviation (SD). Results A total of 668 VDS were successfully calculated for CV. The best-fitted models for the means and SDs are as follow: 1) GA in week = 6.422 + e((-100.653 x GA)) (SD = 0.641 - (0.170 x GA) + (0.009 x GA(2))). 2) BPD = 0.016 x (BPD)(3.589) (SD = 2.663 - (1.410 x BPD) + (0.224 x BPD2)). 3) HC = 0.00017 x (HC)(3.537) (SD = 2.341 - (0.341 x HC) + (0.015 x HC2)). The CV progressively increased with advancing fetal age (GA) and size (BPD, HC). Conclusions The reference intervals of CV, theoretically best representing cardiac size, in relation to GA, BPD, HC, and EFW were first established and Z-score was readily calculated. These will be helpful in detection of cardiac abnormalities, especially those associated with cardiomegaly.