Ultrasound Evaluation of Foetal Nasal Bone and Maxillary Bone Length in the Second and Third Trimester TC18-TC20
Dr. VN Amogh,
S/o Dr. V L Nandish, Door No. 1183, Hospital Road, Ashok Nagar, Vellorep-632001, Tamil Nadu, India.
Introduction: Genetic diseases are the major causes of perinatal death and childhood disabilities. Fetus with a genetic disease have either major structural malformation or minor abnormalities (known as markers) that are detected during sonographic examination. Antenatal ultrasonography now permits the measurement of numerous parts of the fetal body, and nomograms have been developed that help to distinguish normal from abnormal fetal biometry.
Aim: 1) To define a nomogram for Nasal and Maxillary bone length in the local population of Salem. 2) To assess the correlation between nasal bone and maxillary bone length with bi-parietal diameter, Head Circumference (HC), Abdominal Circumference (AC) and Femur Length (FL).
Materials and Methods: The present study was a prospective, cross-sectional study conducted in Department of Radiodiagnosis, Vinayaka Missions Medical College, Salem Tamil Nadu, India. Study was conducted for period of one year from September 2012-September 2013. A total of 250 patients with routine antenatal check-up scan were included in the study. Measurement of Bi-Parietal Diameter (BPD), HC, AC, FL, NBL, MBL with 5th, 50th and 95th percentiles of each parameter was calculated. Pearson's correlation coefficients were calculated to examine the strength of the linear relationship between the nasal and maxillary bone with gestational age, BPD, HC, AC, and FL. For each parameter, regression analysis was used as a dependent variable to calculate the equation of the linear fitted function with each of the independent variables.
Results: The maternal age ranged from 17 years to 37 years. The gestational age by Last Menstrual Period (LMP) ranged from 12 weeks to 40 weeks. The mean nasal bone length increased linearly with gestational age from 2.9 mm at 12 weeks to 13.1 mm at 40 weeks. The mean maxillary bone length increased linearly with gestational age from 8.7 mm at 12 weeks to 15.6 mm at 40 weeks. Significant statistical correlation was found between nasal and maxillary bone length and BPD, HC, AC and FL.
Conclusion: Normative data for ultrasonographic measurements of the fetal nasal and maxillary bone lengths throughout pregnancy are provided for the local population of Salem Tamil Nadu, India. These data potentially allow the prenatal diagnosis of abnormal nasal and maxillary bone length which is a marker for chromosomal defects.