vertex presentation
Fetal presentation where the head is the presenting part with the neck flexed, positioning the occiput as the leading point.
Full Definition
Vertex presentation is the most common and optimal fetal presentation for vaginal delivery, occurring in approximately 95% of term pregnancies. In this presentation, the fetal head is the presenting part with the neck in flexion, allowing the smallest diameter of the fetal head (suboccipitobregmatic) to navigate through the birth canal. The occiput serves as the presenting point, and fetal position is described in relation to the maternal pelvis (e.g., left occiput anterior, right occiput posterior). Vertex presentation contrasts with other cephalic presentations such as face or brow presentation, where the neck is extended rather than flexed.
Usage
Usage note: Distinguish from other types of cephalic presentation. Always specify position when known (e.g., 'vertex presentation, LOA').
In Context
- "Ultrasound confirmed vertex presentation at 36 weeks with the fetal head well-flexed." — Third trimester ultrasound report
- "The patient presented in active labor with vertex presentation and left occiput anterior position." — Labor admission note