During the third stage of labour, the uterine muscles contract powerfully and lead to:

RIMS Nursing Officer - 2022

Obstetrics & Gynaecology

Easy

Appeared in: RIMS Nursing Officer - 2022

Explanation

The third stage of labor begins after the baby's birth and ends with the expulsion of the placenta and membranes.
During this stage, the uterine muscles contract powerfully and retract.
The myometrium has a unique mesh-like structure of muscle fibers that surround the blood vessels supplying the placental site.
This contraction and retraction cause the muscle fibers to act like 'living ligatures,' compressing the torn blood vessels.
This mechanical compression is the primary mechanism for achieving hemostasis and preventing postpartum hemorrhage.

Option A: Relaxation of blood vessels would cause vasodilation, leading to increased and uncontrolled bleeding, which is the opposite of the intended physiological effect.
Option B: Profuse bleeding is a sign of a complication, specifically uterine atony (failure of the uterus to contract), not the result of powerful contractions.
Option D: A pathological retraction ring (Bandl's ring) is a sign of obstructed labor, where the lower uterine segment becomes dangerously thinned. It typically occurs during the second stage, not the third.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiology of the Third Stage of Labor as background academic context rather than a clinical decision trigger.
Nurses actively manage the third stage of labor by administering uterotonic drugs (e.g., oxytocin) and assessing uterine tone to ensure it is firm and contracted.
A key postpartum nursing assessment is palpating the uterine fundus. A firm, 'well-contracted' fundus at the level of the umbilicus indicates effective hemostasis. A soft, 'boggy' uterus is a sign of atony and an impending PPH emergency requiring immediate intervention.
What if? If a patient had a prolonged labor augmented with oxytocin, her uterus would be at an increased risk for atony due to muscle fatigue. The nurse must be extra vigilant in assessing for a firm fundus and be prepared to administer additional uterotonics and perform vigorous fundal massage.

How to Approach the Question

Identify the core concept: The question asks for the direct physiological result of powerful uterine contractions during the third stage of labor.
Recall the primary goals of the third stage: delivery of the placenta and prevention of hemorrhage.
Analyze the action described: 'Powerful uterine muscles contract'. Think about the mechanical effect of muscle squeezing on the structures within it, especially blood vessels.
Evaluate the options based on this physiological action:
Does contraction cause relaxation of vessels? No, it causes constriction. Eliminate A.
Is profuse bleeding the intended goal of contraction? No, it's the opposite. Contractions are meant to stop bleeding. Eliminate B.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 p. 67-69

E6 Midwifery Obstetrics and Gynecology Nursing Sandeep Kaur p. 48-56