Evaluation of normal fetal hard palate by three-dimensional ultrasonography

Objective To investigate the method for the normal three-dimensional ultrasound imaging and the characteristics of the fetal hard palate.Methods 210 single fetus free of deformity were examined using three-dimensional ultrasound（3DUS）.Offline analysis was made after reconstruction,the hard palate was observed and the width was measured. Results With reconstruction, the fetal palate was clearly displayed.197 cases in 210 cases were successfully displayed （93.8%）.The front palate and both frontalis processus of maxillary bone composed similar triangular structure in the coronal plane. The retral part showed sustained linear hyperechoic and the radian increased along with the gestational age. Early palate showed flaky hyperechoic in the cross section and it became horse-shoe shaped in the second or third trimester pregnancy surrounded by alveolar bone. Linear regression yielded the following formula for the hard palate width （PW） according to gestational age （GA） ：PW = - 0.547 ＋ 0.013 × GA（ r = 0.982, P 0.001）.Conclusions 3DUS acquired palate images fast and easily.The hard palate in the coronal,sagittal and cross plane showed obvious characteristic images in different gestational stages.With increasing gestational age, the curvature, width, trend and the contrast with the surrounding tissue had the corresponding changes. The successful three-dimensional image reconstruction of the postnasal triangle and the retral part of fetal hard palate would have an important significance in terms of assessing its continuity and integrity. Key words: Ultrasonography, three-dimensional ;  Fetus ;  Palate, hard