Reference ranges for fetal septum primum excursion from 14 to 40 weeks' gestation.

OBJECTIVES

The purpose of this study was to establish reference ranges for septum primum excursion and the septum primum excursion index.

METHODS

Normal singleton pregnancies with certain dates from 14 to 40 weeks' gestation were enrolled to acquire spatiotemporal image correlation volume data sets. The stored data sets were subsequently displayed offline to measure septum primum excursion and the left atrium diameter. The measured values were regressed to identify the best-fitted model as a function of gestational age and biparietal diameter.

RESULTS

A total of 624 volumes were successfully measured, and normal reference ranges for predicting means and standard deviations of septum primum excursion and the septum primum excursion index were established based on best-fitted equations. The septum primum excursion index was relatively constant throughout pregnancy (mean ± SD, 0.474 ± 0.082), whereas septum primum excursion increased with gestational age and biparietal diameter as follows: (1) septum primum excursion = -6.30 + 0.667 × gestational age - 0.009 × gestational age(2); SD of septum primum excursion = 0.219 + 0.02 × gestational age; and (2) septum primum excursion = -3.342 + 1.933 × biparietal diameter - 0.102 × biparietal diameter(2); SD of septum primum excursion = 0.330 + 0.065 × biparietal diameter. Percentile charts for predicting septum primum excursion and equations for Z score calculation were also provided.

CONCLUSIONS

Normal reference ranges for fetal septum primum excursion and the septum primum excursion index have been provided. These normative data may be useful tools for assessment of hemodynamics through the foramen ovale or left ventricular diastolic function.