OP37.08: Quality of three‐dimensional (3D) volume datasets for examination of the fetal secondary palate at the midtrimester anatomy scan

Abstract

To determine the feasibility of obtaining adequate 3D volume datasets for examining the fetal secondary palate at the midtrimester scan. 3D datasets of the fetal secondary palate were obtained from consecutive, structurally normal second-trimester fetuses. 3D volumes were obtained with the same settings used for the standard two-dimensional scan and no additional time was allocated for examination of the palate. Multiplanar mode views were evaluated for the quality of the 3D datasets to identify the secondary palate. The quality of the datasets was classified as good, fair, and poor according to the visualization of the secondary palate, position of the fetal face, and presence of shadowing from surrounding bones or fetal limbs. 97 women met entry criteria. One to 4 3D volumes were obtained during each scan at a median gestational age of 22 weeks (range, 18–23). In 13 (13.4%) cases, it was not possible to obtain a midsagittal view of the face due to fetal position and/or persistent interposition of fetal limbs throughout the scan. 3D dataset quality was considered as good in 60% of cases, fair in 18%, and poor in additional 9% of the cases, although technical factors hampered optimal visualization in 47% of the cases. The main factors limiting visualization were shadowing from the primary palate in fetuses with flexion of the head in 30 cases, interposition of, or shadowing from, fetal arms or legs in 11, inability to obtain a midsagittal plane in 8, and poor image quality in 1. It is not feasible to obtain adequate 3D volume datasets for evaluation analysis of the fetal secondary palate in almost half of the midtrimester fetuses. However, suboptimal visualization is primarily due to factors related to fetal position rather than equipment or image quality. This suggests that a dedicated scan, during which adequate time can be devoted to obtaining a satisfactory position in which the fetal face can be evaluated, may be warranted in high-risk cases.