Study of absent/unossified or hypoplastic nasal bone on ultrasound and its association with aneuploidies

Abstract

Introduction: Down syndrome is the most common chromosomal abnormality in neonates. Nasal bones are easily identifiable markers on genetic sonograms. AHNB in children with Aneuploidy has been detected by first and second trimester ultrasonography. Evaluation of nasal bone may constitute an additional marker to increase the efficacy of screening for trisomy 21 and can result in major reduction in the need for invasive testing. Aim & Objectives: To study pregnancy outcome wherein fetuses are diagnosed with absent/unossified or hypoplastic nasal bone (AHNB) on ultrasound in first or second trimester of pregnancy and its association with aneuploidies. Material and Methods: The retrospective study mainly aimed to evaluate the clinical value of AHNB alone or in combination with other soft markers or structural abnormalities for detection of aneuploidy. Total number of 92 patients with AHNB diagnosed on ultrasound over a period of 9 years were included and their outcome studied. Results: Of 92 cases studied with AHNB 66.3% had normal pregnancy outcome. Isolated absent nasal bone was associated with abnormal karyotype in only 5% cases and those with soft markers or structural abnormalities were associated with abnormal karyotype in 56.25% cases. So, use of isolated AHNB in ultrasonography may not be an effective screening tool for Aneuploidy. Conclusion: In case of finding of isolated absent nasal bone, counseling needs to be done, to assure the couple against pregnancy termination and if termination desired, not before karyotyping.