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30 Cards in this Set
- Front
- Back
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2 Types of twins:
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-Dizygotic
-Monozygotic |
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What are dizygotic twins?
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Fraternal - can be different sex because there's 2 separate fertilized oocytes
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What are monozygotic twins?
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Identical, same sex, genetically identical because it was one oocyte fertilized that split after fertilization.
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What percentage of twins are dizygotic/fraternal?
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2/3
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What type of membrane arrangement do dizygotics usually have?
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Separate - Diamniotic, Dichorionic
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What is "Superfecundation"?
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Fertilization of 2 or more oocytes in the same menstrual cycle, but by different dads.
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What is superfetation?
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2 fertilization events in 2 separate menstrual cycles - doesn't occur in humans.
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What determines the type of Membrane arrangement in Monozygotic twins?
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The time at which splitting of the one blastocyst occurs
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What results when blastomeres separate before day 3?
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Dichorionic/diamniotic - BEST arrangement; 1/3 of monozygotic twins do this.
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What type of membrane arrangement do MOST monozygotic twins have? When does it occur?
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2/3 have Diamniotic, Monochorionic. Separation occurs between days 3-8.
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Why is diamniotic/monochorionic not so good?
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Because 15-30% of the twins with this arrangement can have TTTS
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TTTS is:
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Twin-Twin Transfusion syndrome
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What membrane arrangement is rare? Why is it bad?
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Monochorionic/monoamniotic - leads to placental anastomosis
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What is TTTS?
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Chorioangiopagus - imbalanced blood flow resulting in polycythemic:anemic twins.
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In what type of twins does TTTS occur?
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ONLY monozygotic
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What is the frequency of monozygotic twins?
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Constant; 1/250 - 300 pregnancies - hasn't changed for DECADES!!!
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What is the frequency of Dizygotic twins? How is this determined?
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Twins = 1/90
Triplets = 1/90^2 Quads = 1/90^3 (n-1) |
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What is the hypothesis for determining frequency of dizygotic multiples?
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Hellin's hypothesis
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What is the most common type of anastomosis in TTTS?
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Artery - to - Artery
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What method can be used to stop the anastomosis in TTTS?
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FLOC - fetoscopic lasor oblation of chorioangiopagus.
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IUGR
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-Usually placnental problem ie only one artery
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Meconium aspiration
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Mainly affects lungs - breathe in first poop
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Interventricular bleeding
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-Cerebral palsy
-Hydrocephaly if blocked |
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Cutis aplasia
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Skin abnormality signals underlying CNS defect
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Ichthyosis
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Herperkeratinized skin
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Group B Strep
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most common infection in newborns
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Most common ch' abnormality:
-Diagnostic tool |
Down's syndrome --> decreased AFP
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Oligohydramnios
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Potter's syndrome
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Cornelia de lange
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little elves
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Marfan's syndrome
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Wise old man
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