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.
Early structural defects include the following:….?
a. Caudal malformations (sirenomelia, sacrococcygeal teratoma)
b. Urologic malformations (cloacal or bladder exstrophy)
c. The vertebral anomalies, anal atresia, cardiac, tracheoesophageal, renal, and limb defects (VACTERL) spectrum
d. Neural tube defects (anencephaly, encephalocele, or holoprosencephaly)
e. Defects of laterality (situs inversus, polysplenia, or asplenia)
What is Twin reversed arterial perfusion (TRAP sequence)…?
Twin reversed arterial perfusion (TRAP sequence) is a rare problem (in 1% of monochorionic twins).
One twin is normal and the other twin is a poorly developed mass of tissue.
One twin is the pump twin and the other is an acardiac twin (no heart).
The abnormal embryo receives only low-pressure blood flow through the umbilical artery and preferentially perfuses its lower extremities
What is Goldenhar’s syndrome ..?
Vascular disruptions that occur later in gestation
facio-auriculo-vertebral defects
What is incidence of Conjoined twins..?
Conjoined twins are rare and occur in approximately 1 in 50,000 to 100,000 births.
Most common site of fusion in Conjoined twins…?
The most common sites of fusion are the chest and/ or abdomen.
What is TTTS ,..?
The pathophysiology of TTTS is not completely understood, but placental vascular anastomoses, unequal placental sharing, and abnormal umbilical cord insertions are all necessary for TTTS to occur
Exapand TTTS….?
twin-totwin transfusion syndrome (TTTS)
Complications in the donor include in TTTS …?
anemia, hypovolemia and resultant activation of the renin–angiotensin–aldosterone system, growth restriction, brain ischemic lesions, renal hypoperfusion and insufficiency, oligohydramnios (“stuck twin”), lung hypoplasia, limb deformation, and high risk of fetal demise
Complications in the recipient include
Complications in the recipient include polycythemia, thrombosis, cerebral emboli, disseminated intravascular coagulation (DIC), polyhydramnios, progressive cardiomyopathy due to volume overload, fetal hydrops, and demise
Diagnostic criteria for TTTS…?
Diagnostic criteria for TTTS include monochorionicity, polyhydramnios in the sac of one twin (the recipient) and oligohydramnios in the sac of the other twin (the donor), umbilical cord size discrepancy, cardiac dysfunction in the polyhydramniotic twin, abnormal umbilical artery and/or ductus venosus Doppler velocimetry, and significant growth discordance (>20%)
Quintero staging system is used for …?
disease severity and progression of disease, and provide criteria for escalation of care in TTTS
system is based on a series of ultrasonographic findings and does not include fetal echocardiographic findings.
Treatment for TTTS ….?
fetoscopic laser photocoagulation or radiofrequency ablation of placental anastomoses for stages II to IV at <26 weeks’ gestation
What is TAPS …?
Twin anemia polycythemia sequence (TAPS) is another rare complication of monochorionic twins.
This is diagnosed based on discordant MCA Doppler abnormality, suggesting fetal anemia in one and polycythemia in the other twin
