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30 Cards in this Set

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