Nomogram of nasal bone length at 11-14 week of gestation in Indian women and their follow up till delivery

Abstract

INTRODUCTIONThe first trimester screening in pregnancy is very effective in diagnosing chromosomal abnormalities and assessment of nasal bone is one of the effective secondary factors. Maternal age, Nuchal translucency (NT) and free β-hCG and PAPP-A (combined test) is found to have 85-95% detection rate for fetal aneuploidy with a false-positive rate of 5% whereas combined test along with nasal bone (NB) or tricuspid flow or ductus venosus flow has detection rate of 93-96% and false positive rate of 2.5% for euploid, 60% of trisomy 21, 53% for trisomy 18 and 45% for trisomy 13.1 Hence, NB absence or hypolplasia is a promising component of screening test.2 Ethnic differences in NB length have been reported. 3 To define NB hypoplasia, nomograms are set in Caucasian, African-American, Korean and Chinese populations. [4][5][6][7] An objective approach of measurement of NB length according to gestational age and setting nomogram helps to ascertain NB hypoplasia. This can also be used for Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Background:The measurement of nasal bone length (NBL) according to gestational age and setting nomogram helps to ascertain NB hypoplasia. This can be used for early detection of trisomy 21 and other chromosomal abnormalities in low risk population. The objective of the study was to obtain nomogram of fetal nasal bone length at 11-14 weeks gestation with known prognosis pregnancies. Methods: A single centre, prospective crosses sectional study. Nasal bone length of 323 choromosomal and structural normal fetuses at 11-14 weeks gestation were measured by transabdominal ultrasonography, prospectively. The correlation between nasal bone and other biometric parameters was assessed by regression analysis and average±SD of nasal bone lengths were measured.