Nasal bone length: the long and short of it. Evaluation of the reference values for the fetal nasal bone length at 16 to 25 weeks of gestational age in an Indian population. (20th June 2013)

• Record Type: Journal Article
• Authors: Sharma, Akshatha; Tayal, Tulika; BH, Narayani; Radhakrishnan, Prathima; Kaul, Anita
• Is Part Of: Prenatal diagnosis. Volume 33:Number 8(2013:Aug.)
• Page Start: 800
• Page End: 803
• Publication Date: 2013-06-20
• Subjects: Prenatal diagnosis -- Periodicals; Fetus -- Diseases -- Diagnosis -- Periodicals; Electronic journals; 618.32075
• DOI: 10.1002/pd.4114
• Languages: English
• ISSNs: 0197-3851

Abstract

ABSTRACT: Objective: To establish a reference interval range for the fetal nasal bone length (NBL) in an Indian population. Methods: A retrospective study of antenatal ultrasound records of fetuses at 16 to 25 weeks in singleton pregnancies. NBL, biparietal diameter (BPD) and femur length were noted in 6436 observations of singleton, euploid, nonmalformed pregnancies. Results: The 50th centile for NBLs increased from 3.4 to 6.9 mm from 16th to 25th week of gestational age. The relation between nasal bone and gestational age, BPD and femur length were found and noted. The NBLs were found to be shorter when compared with other ethnicities. Conclusions: A reference range for fetal NBLs at 16 to 25 weeks in an Indian population and its relation with fetal biometry was established. © 2013 John Wiley & Sons, Ltd. Abstract : What is already known about this topic? Absence of nasal bone and its hypoplasia has already proven to be an important marker for Down syndrome detection prenatally in the first trimester and the second trimester. Nasal bone hypoplasia has been defined variously by different authors in different ethnic population. The BPD/NBL ratio has been evaluated and is said to detect 81% of Down syndrome (FPR 11%). 10 What does this study add? As far as we know, no study has evaluated the NBLs in the second trimester in an Indian population. The study includes a representative population – North and South Indian – thus covering a divergent population within India. It also highlights the fact that the BPD/NBL ratio appears to be an ethnicity – independent marker. It aims to minimise the false positives in the second trimester, which is still the primary gestational period for prenatal Down syndrome screening in India.