Multiple Births Flashcards
Monozygotic (MZ) twins…..?
Monozygotic (MZ) twins originate and develop from a single fertilized egg (zygote) as a result of division of the inner cell mass of the blastocyst.
MZ twins are the same sex and genetically identical
Dizygotic (DZ)….?
Also called as fraternal twins originate and develop from two separately fertilized eggs
When Chorian and amnion begins to forms …?
The chorionic and amniotic sacs surround the fetus.
The chorion begins to form on day 3 after fertilization,
the amnion begins to form between days 6 and 8.
The two membranes eventually fuse to form the amniochorionic membrane.
MZ twins commonly have how many placenta .?..?
MZ twins commonly have one placenta with one chorion and two amnions (monochorionic diamniotic) or,
rarely, one placenta with one chorion and one amnion (monochorionic monoamniotic).
Splitting before 3rd day …?
If early splitting occurs before the formation of the chorion and amnion (days 0 to 3),
MZ twins can have two placentas with two chorions and two amnions (dichorionic diamniotic).
A dichorionic diamniotic placenta results…?
A dichorionic diamniotic placenta results when early splitting occurs on days 0 to 3
A monochorionic diamniotic placenta results…..?
when splitting occurs about days 4 to 7
monochorionic monoamniotic placenta results …?
splitting of the egg after this time (days 8 to 13) results in a monochorionic monoamniotic placenta
At what time of time results in conjoined twins…..?
On day 14 and thereafter, the primitive streak begins to form and late splitting of the embryo at this time results in conjoined twins.
DZ pregnancies or multizygous pregnancies reason …?
DZ pregnancies or multizygous pregnancies result when more than one dominant follicle has matured during the same menstrual cycle and multiple ovulations occur. Increased levels of follicle-stimulating hormone (FSH) in the mother have been associated with spontaneous DZ twinning
Fetal growth discordance in twin gestation….?
Fetal growth discordance is typically defined as a difference in birth weight of more than 20% of the larger twin’s weight.
It can also be categorized as mild (<15%), moderate (15% to 30%), or severe (>30%)
Intrauterine fetal demise (IUFD) definition …?
Intrauterine fetal demise (IUFD) refers to fetal demise after 20 weeks’ gestation but before delivery and is confirmed by ultrasonographic evidence of absent fetal cardiac activity
there is a significant risk (20% to 40%) of neurologic injury in the surviving co-twin in which type pregnancy ..?
MZ twins have placental vascular connections with resulting shared circulations
result of associated severe hypotension or thromboembolic events on death of the co-twin
What is fetus papyraceous…?
In DZ twins case, the co-twin is either completely resorbed if death occurs in the first trimester or compressed between the amniotic sac of its co-twin and the uterine wall (fetus papyraceous)
Structural defects specific to MZ twins include …?
(i) early malformations that share a common origin with the twinning process,
(ii) vascular disruption syndromes, and
(iii) deformations.