Ultrasound evaluation of the normal fetal pharynx.
OBJECTIVE: To obtain normative data for fetal pharyngeal diameter and to investigate the ability to visualize pharynx at different gestational ages during routine prenatal sonography. METHODS: Sonographic studies were performed in 292 consecutive pregnant women. The diameters of the pharynx were measured and our ability to visualize pharynx was evaluated at different gestational ages. RESULTS: Sonographic measurements of the pharyngeal diameter were obtained in 153 of the 292 fetuses. The diameter of the pharynx increased from a mean of 4.5+/-0.53 mm at 16 weeks to 9.1+/-1.72 mm at 36 weeks. Pharyngeal diameters showed a significant positive relationship with advancing gestational age (p<0.0001, R2=0.571). The differences in visualization among different gestational age groups were found to be significant (p<0.05 by Chi-Square). CONCLUSION: This study reports normative data for fetal pharyngeal diameter. Pharyngeal measurements were similar to previous reports in the literature. Our success in visualizing the pharynx was best between 21 and 30 weeks of gestation. This period might be the optimum time for evaluating fetal pharynx.