2D trans abdominal ultrasound was done during the first stage of labor. If fetal position is occiput anterior and fetal presentation is vertex, two dimensional sagittal picture of the fetal head and upper spine was acquired and stored in the ultrasound machine. On this image, the offline measurement of the angle formed by a line tangential to the occipital bone and a line tangential to the first vertebral body of the cervical spine (occiput-spine angle) will be performed to quantify the degree of fetal head flexion in respect to the trunk.~The sonographer was not involved in the patient's care and the managing obstetrician was blinded to the ultrasound findings and the occiput-spine angle. For each patient of the study group, the progress of labor using a partogram ( cervical dilation ,effacement ,consistency, position and station ) and the mode of delivery were assessed retrospectively.
2D trans abdominal ultrasound was done during the first stage of labor. If fetal position is occiput anterior and fetal presentation is vertex, two dimensional sagittal picture of the fetal head and upper spine was acquired and stored in the ultrasound machine. On this image, the offline measurement of the angle formed by a line tangential to the occipital bone and a line tangential to the first vertebral body of the cervical spine (occiput-spine angle) will be performed to quantify the degree of fetal head flexion in respect to the trunk