Aim:
The nasal bone can be imaged with ultrasonography from the 10th week of pregnancy. In situations where the nasal bone is aplastic or hypoplastic, the risk of chromosomal anomalies increases. Thickening of the prenasal soft tissue is also apparent in the vast majority of second-trimester fetuses with Down syndrome. In addition to these, corpus callosum is an another fetal structure that can be visualized from 18th weeks of the gestation by ultrasound. Agenesis or dysgenesis of it is related with neuro-disabilities. In this study our objective was to provide reference charts for fetal nasal bone length, prenasal thickness and corpus callosum length obtained by prenatal sonography between 19th and 23rd weeks of pregnancy.
Materials and Methods:
The medical records of pregnant women who were followed-up in Trakya University School of Medicine, Department of Obstetrics & Gynecology, Division of Perinatology during the time period of 1st of January 2018 to 31st of December 2019 were reviewed retrospectively. We studied 167 patients in between 19th and 23rd weeks of pregnancy.
Results:
Nasal bone length, prenasal thickness and corpus callosum length increased as the gestation proceeded. Mean±SD for nasal bone length, prenasal thickness and corpus callosum length (mm) between 19th and 23rd weeks were 6.65±0.7, 4±0.5, 20.1±1.4 respectively.
Conclusion:
Ultrasound measurements of nasal bone length, prenasal thickness and corpus callosum can be performed within the second-trimester anomaly scan, and these measurements appear to be highly necessary because these measurement sensitive for prenatal diagnosis of chromosomal abnormalities and genetic syndromes.
Keywords: Corpus callosum, nasal bone, prenasal thickness