P262: Incidence of sonographic uncoiled umbilical cords in the first half of gestation

Abstract

Objective: Pathologic studies reported that umbilical cords (UC) of embryos show a fully developed helical structure as early as eight weeks of gestation and that the number of umbilical vascular coils present in the first trimester and at term gestation is similar. The purpose of this study was to asses the incidence of uncoiled UC in the first half of gestation. Methods: A prospective cross-sectional study was designed. Each patient was included only once. Color Doppler was used to enhance the definition of the UC vascular coils. An UC was defined uncoiled in the presence of straight UC vessels. Exclusion criteria were 1) chromosomal or structural fetal malformations, 2) single umbilical artery, and 3) multiple pregnancies. Results: During the study period 204 cases were included into the study. Of these, 31 (15.2%) had an uncoiled UC at sonography. The prevalence of uncoiled UC decreases significantly from 100% at a gestational age lower than 8 weeks to 11.8% at 20 weeks gestation. A sharp decrease is evident before 12 weeks of gestation. After this gestational age the proportion of uncoiled UCs does not change. Conclusion: This study further demonstrates that the formation of the UC vascular coils is a time dependent process. The incidence of uncoiled cords changes dramatically in the first trimester of gestation and subsequently remains stable with advancing gestation.