Publication:

Fetal absent/hypoplastic nasal bone: a single center follow up study from a tertiary referral hospital in India

Background This study was undertaken to determine perinatal outcomes in fetuses with absent/hypoplastic nasal bone (AHNB) when considered as a broad entity irrespective of time at which it is identified and identify subgroups with the highest risk of abnormal outcome based on screening status and associated findings.

Methods This was an observational study involving a total of 142 pregnant women whose fetuses were identified with AHNB by ultrasongraphy (USG) during a three year period from January 2016 to December 2018. These women were offered aneuploidy screening/non-invasive prenatal testing (NIPT) or direct invasive testing either alone or in combination. Outcome data was collected and a sub-group analysis was done by dividing them into 8 subgroups based on screening status and associated findings.

Results Out of 12758 scans done during the study period, 142 fetuses (1.11%) were identified with AHNB. 80 (56%) opted the biochemical screening test, 5 (3.5%) opted NIPT while 60 (42.9%) opted for invasive testing. 21 (14.8%) had an abnormal karyotype. In sub-group analysis, the best outcome was seen in group 1, where the biochemical screening was negative and no other aneuploidy markers or anomalies were seen.

Conclusions The present study confirms the association of AHNB with chromosomal disease. However, isolated AHNB with low risk in biochemical screening is rarely associated with aneuploidy. In contrast, a significant no of fetuses yielded abnormal chromosome results when AHNB was associated with high risk in biochemical screening, additional aneuploidy markers or associated anomalies.