Real-time 3-D sonographic observation of fetal facial expression

There have been a few reports about 3-D sonographic observation of fetal movements using dynamic 3-D sonography. However, dynamic 3-D sonography is not real-time, the frame rate being in the region of 4-6 frames per second depending on the size of the region of interest and the number of lines employed. Recently, a new faster 3-D sonography, which acquires up to 28 frames per second, has become available. Using this system, we studied a full range of fetal facial expressions during pregnancy.

A total of 17 normal fetuses in 16 pregnancies (15 singletons and one twin) at 20-38 weeks' gestation was studied using a transabdominal real-time 3-D ultrasound machine. This 3-D ultrasound machine proved capable of providing continuous 3-D sonographic images every 0.05 and 0.035 s. The fetal face was monitored for 15 min for each subject.

Fetal eyelid movement (fetal blinking) was observed in three of 17 fetuses (17.6%). Double blinking was identified in one fetus at 38 weeks. Various types of mouth movement (yawning, a little opening, chewing, and subtle lip movement) could be observed in nine of 17 fetuses (52.9%). In the course of yawn-like opening of the mouth, tongue movements such as tongue thrust and tongue click were clearly shown in three fetuses (17.6%). A lingula movement was also identified in the course of tongue movement.

Real-time 3-D sonography provides a novel means for evaluation of fetal movement, particularly fetal facial expression, in the second and third trimesters. Real-time 3-D sonography might be an important modality in future fetal behavior research and in evaluation of fetal well-being.