Sonographic assessment of normal fetal palate using three-dimensional imaging: a new technique.

OBJECTIVES

The aim of this study was to describe a novel three-dimensional (3D) ultrasound rendering technique to examine the normal fetal posterior palate and to assess its correspondence with the real fetal anatomy.

METHODS

A prospective longitudinal study was conducted from January to October 2005 and included 100 fetuses in a low-risk population. Fetal ultrasound examinations were performed at 17, 22, 27 and 32 weeks' gestation to determine the normal 3D ultrasound view of the fetal palate at different gestational ages. The ultrasound scans were performed using the strict anterior axial plane of the starting reconstruction volume and the underside 3D view of the fetal palate. The 3D view of the fetal palate was compared with the normal anatomical view of the fetal palate obtained by surgical fetopathological examination of fetuses at the same gestational ages. The sonographic visualization rates of seven defined anatomical landmarks of the fetal palate were computed for each gestational age. The visualization rates across gestational ages were compared by use of the Cochrane Q test. The reliability of detection of each anatomical landmark across gestational ages was determined by Cronbach's Alpha.

RESULTS

In all cases a 3D ultrasound view of the fetal maxilla and secondary palate was obtained at each period of gestation and corresponded well to the fetal anatomical specimens. The seven defined anatomical landmarks of the fetal palate were identified in 42-100% of cases. The visualization rates across gestational ages were significantly different in five of these anatomical landmarks. These differences can be explained by different developmental processes of these anatomical structures. The overall reliability of visualization across the gestational ages for the anatomical landmarks was medium to very high (0.73-0.96), except for the landmark interpalatal suture which was low (0.48).

CONCLUSIONS

This technique of anterior axial 3D view reconstruction of the fetal palate seen by an underside view can provide unique diagnostic information on the integrity of the secondary palate. This innovative, simple and rapid technique may become the reference technique in ultrasound investigation of the fetal palate, and should be of value in diagnosing isolated secondary cleft palate or palatal involvement when cleft lip and alveolus are diagnosed.