During active phase of labour head is delivered by

Appeared in: NHM UP Staff Nurse-2021 Shift-2nd

Explanation

The fetal head is delivered from the vaginal outlet by the movement of extension.
This occurs after the head has completed internal rotation and is crowning at the perineum.
During extension, the subocciput (base of the back of the head) pivots under the symphysis pubis.
This allows the sinciput (forehead), face, and chin to sweep over the perineum and be born.

Option A: Flexion is an earlier cardinal movement that facilitates the descent of the head into the pelvis by presenting the smallest head diameter. It is not the movement that delivers the head out of the vagina.
Option C: Abduction is a general anatomical term for moving a limb away from the body's midline. It has no role in the mechanism of labor.
Option D: This option is incorrect because a correct answer, Extension, is listed among the choices.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cardinal Movements of Labor as background academic context rather than a clinical decision trigger.
Understanding the cardinal movements of labor is fundamental for nurses to assess labor progress, identify abnormalities (dystocia), and anticipate the next steps in delivery.
A nurse's ability to recognize the stage of labor by observing these movements helps in providing appropriate support and interventions.
What if? If the head fails to extend and remains flexed or becomes deflexed (e.g., brow presentation), it presents a larger diameter to the pelvic outlet. This can lead to an obstructed labor, increasing the risk of maternal perineal trauma and fetal distress, often necessitating operative vaginal delivery (forceps/vacuum) or a cesarean section.

How to Approach the Question

This is a factual recall question about a key physiological process in obstetrics.
First, identify the core of the question: which specific movement delivers the fetal head.
Recall the cardinal movements of labor in their correct sequence: Engagement, Descent, Flexion, Internal Rotation, Extension, Restitution, External Rotation, and Expulsion.
Differentiate the purpose of each movement. Flexion helps the head navigate the pelvis, but Extension is the action that allows it to emerge from the pelvic outlet.
Eliminate 'Abduction' as it is not a term used in the mechanism of labor.
Select 'Extension' as the final movement for the delivery of the head itself.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 21-39

Practise the full NHM UP Staff Nurse-2021 Shift-2nd

Attempt every question from this paper in a timed mock, then review the full solution for each one.