Ultrasound imaging of the fetal secondary palate: methodological description of a two dimensional approach, and a case series.

Objective The study aims to describe our two-dimensional (2D) ultrasound approach to visualize the fetal secondary palate and plot its growth curve and to describe and demonstrate its clinical implementation. Methods This is a two parts retrospective study. First, we measured the antero-posterior length of the bony secondary palate, from the soft to hard palate interface (SHPI) line to the alveolar ridge, blindly by two operators during routine scans of low-risk fetuses, and plot a longitudinal growth curve. In the second part, we describe four cases of prenatal diagnosis of secondary palate cleft. Results Sixty-eight fetuses were included: 14 to 15 weeks (n = 20), 21 to 24 weeks (n = 32), and 29 to 35 weeks (n = 16). The bony secondary palate elongates along gestation from a mean of 5.3 mm (+/-0.46 mm) at 14 to 15 weeks to 15.9 mm (+/-1.7 mm) at 29 to 35 weeks. We found high intraobserver and interobserver correlation between measurements. All four cases diagnosed by this approach were confirmed postnatally. Conclusions The SHPI, representing the normally developed secondary bony palate, can be imaged in the fetus by direct 2D ultrasound as early as 14 weeks. A gap within or nonvisualization of the SHPI is highly suggestive for a secondary palate cleft.