Measurement of the Fetal Occiput-Spine Angle during the First Stage of Labor as Predictor of the Outcome of Labor

Abstract

ABSTRACT Background: Fetal head “attitude” (relationship of fetal head to spine) in the first stage of labor may have a substantial impact on labor outcome. The diagnosis of fetal head deflexion traditionally is based on digital examination in labor, although the use of ultrasound to support clinical diagnosis has been recently reported. Objectives: To quantify the degree of fetal head deflection via the use of ultrasound during the first stage of labor. To determine whether a parameter derived from ultrasound examination (the occiput-spine angle) has a relationship with the course and outcome of labor. Patients and methods : This was a prospective study conducted at Alhussin Hospital from July 2019 to January 2020. A nonconsecutive series of women with uncomplicated singleton pregnancies at term gestation (37 weeks or more) were submitted to trans abdominal ultrasound during the first stage of labor. Fetal position was occiput anterior and the angle between the fetal occiput and the cervical spine (the occiput-spine angle) was sonographically obtained on the sagittal plane. Results: The mean value of the occiput-spine angle measured in the active phase of the first stage was 126° ± 2.79° (SD). The occiput-spine angle was significantly narrower in women who underwent CS delivery due to labor arrest. A larger occiput-spine angle (i.e., >126°) showed to be significantly associated with a shorter duration of labor. Conclusion: Fetuses with smaller occiput-spine angle (<126°) are at increased risk for operative delivery.