What reflex is an expulsive uterine contraction experienced by the mother during labor?

RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Obstetrics & Gynaecology

Easy

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Explanation

The Ferguson reflex is the neuroendocrine reflex responsible for the strong, expulsive uterine contractions during the second stage of labor.
It is initiated by the mechanical stretching of the cervix and upper vagina as the fetal presenting part descends.
This stretching triggers a positive feedback loop, causing the posterior pituitary to release oxytocin.
Oxytocin stimulates the myometrium to contract more forcefully, which in turn increases cervical stretch, leading to more oxytocin release and progressively stronger contractions until birth.

Option A: This is not a standard medical term for the underlying physiological reflex. It describes the maternal sensation or 'urge to bear down' which is a result of fetal pressure on the pelvic floor, not the cause of the contractions.
Option C: This is a general, non-specific term and does not describe a recognized obstetrical reflex related to labor.
Option D: This is an incorrect term. The correct term is 'Chadwick's sign,' which is an early sign of pregnancy, not a reflex associated with labor.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiological Reflexes in Labor as background academic context rather than a clinical decision trigger.
Understanding the Ferguson reflex is crucial for nurses to recognize normal labor progression and to support the mother's natural, involuntary pushing urges during the second stage.
Nurses should educate patients that the urge to push is a natural reflex and encourage them to work with their bodies, pushing when the urge is strongest, once the cervix is fully dilated.
What if? If a patient has a dense epidural block, the sensory component of the Ferguson reflex may be blunted, diminishing the natural urge to push. In this case, the nurse may need to provide more direct coaching for bearing-down efforts ('directed pushing') based on the contraction pattern observed on the monitor.

How to Approach the Question

First, identify the key concepts in the question: 'reflex,' 'expulsive uterine contraction,' and 'labor.' This points to a specific physiological mechanism.
Evaluate each option against your knowledge of obstetrical physiology.
Recall that the Ferguson reflex is the specific term for the positive feedback loop involving cervical stretch and oxytocin release that drives powerful contractions.
Eliminate 'Urge reflex' as it describes a sensation, not the underlying neuro-hormonal process.
Dismiss 'Pelvic reflex' as too vague and not a standard medical term.
Recognize that 'Chadwick reflex' is a confusion with 'Chadwick's sign,' which is related to early pregnancy, not labor. This confirms the Ferguson reflex as the only correct answer.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 p. 66-68