Background: The gestational age calculation by ultrasonography (USG) at first trimester is based on crown-rump length is more accurate, less erratic than last menstrual period based dating. Utilization of first trimester based scanning in dating the pregnancy will reduce the labor induction rate and consequently reduce the morbidity related to induction of labor.Methods: A comparative cross-sectional study was done among 314 booked antenatal women visiting department of obstetrics and gynecology, BPKIHS for regular check-up between 37 and 41 weeks of gestation. Expected date of delivery was calculated from crown rump length (CRL) of the first trimester scan for USG group while last menstrual period was taken to calculate expected date of delivery for LMP group and were called for induction at 41 weeks of gestation. The rates of labor induction, emergency cesarean section (CS) among induced group, indication of CS and mode of delivery were compared in both the groups.Results: There was 14% labor induction rate in USG group and 24.2% in LMP (last menstrual period) group and differed significantly (p=0.022). There was no difference in the mode of delivery among participants in either groups. The rate of emergency CS among women undergoing induction of labor was 54.5% and 39.5% respectively for USG and LMP groups (p=0.258). Overall, non-reassuring fetal heart rate was the most common indication for CS in both the groups.Conclusions: The finding suggests first trimester scan among all pregnancies will reduce the post-dated inductions, as well as need of CS.
EP04.05: Hypoplasia or absence of one or both nasal bones in the first trimester scan as an important marker for trisomies with high specificity
