HCG secreted by?

Appeared in: PGIMER Sangrur NO - 2023

Explanation

Human Chorionic Gonadotropin (hCG) is a key hormone of early pregnancy, often called the 'pregnancy hormone'.
It is secreted by the syncytiotrophoblast cells, which are specialized cells originating from the trophoblast.
The trophoblast is the outer layer of the blastocyst that implants into the uterine wall and develops into the placenta.
The primary role of hCG is to signal the corpus luteum in the ovary to continue producing progesterone, which is vital for maintaining the uterine lining and supporting the new pregnancy.

Option A: The fetal sac, which includes the amniotic and chorionic membranes, encloses the fetus but is not the site of hCG production.
Option B: Amniotic fluid contains hCG, but it does not produce it. The hormone enters the fluid from the placenta and fetal circulation.
Option D: The uterus is the site of implantation and fetal development. Its lining (endometrium) is maintained by progesterone, whose production is stimulated by hCG, but the uterus itself does not secrete hCG.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Source of Human Chorionic Gonadotropin (hCG) secretion as background academic context rather than a clinical decision trigger.
Measuring hCG levels in a woman's blood or urine is the fundamental principle behind pregnancy tests.
In early pregnancy, serial hCG levels are monitored to assess viability. A normal pregnancy shows levels doubling approximately every 48-72 hours. Failure to do so may suggest a miscarriage or an ectopic pregnancy.
Abnormally high hCG levels can be an indicator of a multiple gestation (e.g., twins) or gestational trophoblastic disease (molar pregnancy).

How to Approach the Question

This is a factual recall question based on reproductive physiology.
Identify the core subject of the question: the origin of the hormone HCG.
Recall the sequence of events in early pregnancy: fertilization, blastocyst formation, implantation, and placental development.
Connect HCG to its function. It's the hormone that 'announces' pregnancy to the mother's body, starting right after implantation.
Evaluate the options based on this timeline. The structure that implants and forms the placenta is the blastocyst, specifically its outer layer, the trophoblast.
Eliminate the other options: the fetal sac and amniotic fluid are byproducts of development, and the uterus is the host organ, not the producer of this specific hormone.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 p. 58-60

E6 Gynecology Williams p. 351-421

E6 Obstetrics Williams p. 4

Practise the full PGIMER Sangrur NO - 2023

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