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Kaplan OB/Gyn

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Karyotype associated with Klinefelter syndrome
47,XXY
When is PUBS performed?
after 20 wks
At what GA is amniocentesis peformed when for Rh isoimmunization testing?
after 24 wks
What is the accuracy of gestational dating at GA < 12 wks?
+/- 5 days
High levels of AFP on triple screen
suggest increased risk of neural tube defects
What is the triple screen?
it is a SCREENING test (not diagnostic) for genetic abnormalities (esp. trisomy 21) and neural tube defects
At what GA is CVS performed?
between 9 and 12 wks
Name the main advantage of CVS:
karyotyping available at a very early age (earlier than amniocentesis)
What is the most common aneuploidy?
trisomy
At what GA is amniocentesis peformed when for genetic testing
15-20 wks
What is the optimal GA for IDing fetal anatomic structural anomalies by US?
18-20 wks
Aneuploidy
numeric chromosome abnormalities in which cells do not contain 2 complete sets of 23 chromosomes
Pregnancy loss rate of amniocentesis:
0.5%
Mosaicism
presence of 2 or more cytogenetically distinct cell lines in the same individual
What findings on triple screen suggest increased risk of Down's syndrome?
high bHCG and inhibin levels with low AFP and estradiol
Pregnancy loss rate of fetoscopy:
3-5%
What 3 levels are measured in a triple screen?
1) MS-AFP; 2) bHCG; 3) estradiol
2 findings of Turner's syndrome on US
1) nuchal skin fold thickening; 2) cystic hygroma
Pregnancy loss rate of PUBS
1-2%
Name a common polyploidy
incomplete molar pregnancy in which an egg is fertilized by 2 sperm (--> triploidy, 69 chromosomes)
Percutaneous umbilical blood sampling (PUBS)
sonographically guided transabdominal aspiration of fetal blood from the umbilical vein
4 Indications for PUBS:
1) fetal karyotyping; 2) IgM antibody detection; 3) blood typing; 4) intrauterine blood transfusion
Indications for genetic counseling
1) AMA; 2) multiple fetal losses; 3) previous child --> neonatal death, mental retardation, aneuplody, known genetic disorder; 4) family history: genetic diseases, birth defects, mental retardation; 5) abnormal prenatal tests: triple screen, US; 6) parental aneuploidy
Chorionic villous sampling
aspiration of placental tissue precursors under sonographic guidance for fetal karyotyping
Amniocentesis
transabdominal needle withdrawal of amniotic fluid under sonographic guidance
Most common cause of aneuploidy:
nondisjunction
At what GA is amniocentesis peformed when for fetal maturation testing
after 34 wks
What is added to the triple screen in the quad screen?
dimeric inhibin A (DIA)
What is the pregnancy rate loss with CVS?
0.7%
Polyploidy
numeric chromosome abnormality in which cells contain complete sets of extra chromosomes
Name 3 general indications for amniocentesis:
1) genetic testing; 2) Rh isoimmunization; 3) fetal lung maturity studies
2 indications for fetoscopy
1) fetal tissue biopsy; 2) coagulation of placental vessels in twin twin transfusion syndrome
What is the genetic defect associated with cri du chat syndrome?
deletion of short arm of chromosome 5 (del 5p)
Twin twin transfusion syndrome
complication of pregnancy with high morbidity and mortality that occurs when two or more fetuses share a common (monochorionic) placenta; the connection in circulatory systems results in the donor twin pumping blood to the recipient twin without receiving blood in return
Karyotype associated with Turner's syndrome
45,X

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