High incidence of cord entanglement during early pregnancy detected by three-dimensional sonography.

We sought to determine the incidence of cord entanglement around any part of fetal body during early gestation using three-dimensional (3D) sonography. A prospective consecutive study was designed and 3D ultrasound was performed. Two hundred thirty-seven singleton pregnancies between 13 and 16 weeks were included. Cord entanglement was defined when one or more of the following was detected: cord around neck, hand, leg, thorax, abdomen, shoulder. We considered cord entanglement when one or more loops of cord encircled any part of body. Free-floating cord through all its length in the amniotic fluid was defined as free cord. Cord entanglement was observed in 149 (62.9%) patients. Of those, 64 (42.9%) cords were entangled around necks, 23 (15.4%) around legs, 19 (12.7%) around hands, 7 (4.8%) around abdomens, 36 (24.2%) around other body parts (thorax, shoulder, and pelvis). The incidence of total cord entanglement was similar between 13 and 16 weeks' gestation and was between 60 and 65%. The incidence of early pregnancy cord entanglement was 62.9%. According to the literature, this incidence is higher in comparison to the incidence of cord entanglement later in pregnancy. Therefore, this phenomenon may be considered a part of normal early fetal development.