Objective: The upper limit of the fetal atrial width in normal fetuses is debated. This was a prospective cohort evaluation of the lateral ventricular width with special regard to the upper limit of its size.
Methods: Measurements of fetal atrial ventricular size were obtained by abdominal ultrasonography in 427 male and female fetuses between 20 and 40 weeks' gestation of normal singleton pregnancies. In addition, reanalysis of previous data (8 studies) and the current data was performed to produce a pooled mean and SD.
Results: The mean ventricular width +/- SD was 6.2 +/- 1.2 mm. The ventricular width did not show significant modification throughout gestation. Reanalysis of the current and previous studies (8216 cases) yielded a pooled mean of 6.4 +/- 1.2.
Conclusions: According to the current and previous studies, the upper cutoff of fetal ventricular atrium width should be 10 mm. This cutoff represents a range of approximately 3 SDs above the pooled mean, corresponding to a 99.74% confidence interval.