The fertilization of two different ova released in two different menstrual cycles is called?

Appeared in: MNS 2024

Explanation

Superfetation is the correct term for the fertilization of an ovum when a fetus is already present in the uterus.
This implies that the second fertilization event occurs in a subsequent ovulatory cycle, after the first pregnancy has already been established.
The key differentiator is that the two ova are from two separate and distinct menstrual cycles, leading to fetuses of different gestational ages.

Option A: Superfecundation involves the fertilization of two ova released during the same menstrual cycle, although often from different acts of intercourse.
Option C: Fetus papyraceous is not a method of fertilization. It describes a complication of multiple pregnancies where one fetus dies in utero and becomes flattened and mummified.
Option D: Fetus acardiacus is a severe congenital anomaly, not a type of fertilization. It refers to a twin that fails to develop a heart and relies on the other twin for blood supply (TRAP sequence).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Terminology of rare events in multiple gestations as background academic context rather than a clinical decision trigger.
Superfetation is exceptionally rare in humans but is well-documented in some animal species. Its occurrence challenges the understanding that hormonal changes during pregnancy completely suppress ovulation.
Clinically, it would present as a twin pregnancy with a significant size and developmental discrepancy between the fetuses, which could be mistaken for severe intrauterine growth restriction (IUGR) of one twin.
What if? If the two ova were from the same cycle but fertilized by sperm from two different males, the phenomenon would be called superfecundation with heteropaternity, not superfetation.

How to Approach the Question

First, identify the core components of the question stem: 'fertilization', 'two different ova', and the key phrase 'two different menstrual cycles'.
This is a definition-based recall question. Your task is to match the specific scenario described to the correct medical term.
Evaluate each option against the key phrase 'two different menstrual cycles'.
Superfetation specifically describes fertilization occurring in a subsequent cycle after a pregnancy has begun.
Superfecundation refers to fertilization within the same cycle.
Fetus papyraceous and fetus acardiacus are complications or anomalies that occur after fertilization, not types of fertilization itself. This allows you to eliminate them.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1048-1050

Practise the full MNS 2024

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