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

Abstract

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 × GA) (SD = 0.641 − (0.170 × GA) + (0.009 × GA2)). 2) BPD = 0.016 × (BPD)3.589 (SD = 2.663 − (1.410 × BPD) + (0.224 × BPD2)). 3) HC = 0.00017 × (HC)3.537 (SD = 2.341 − (0.341 × HC) + (0.015 × 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.