55. Genetic Studies Flashcards
congenital anomalies account for ______% of _____ deaths
- 20-25%
- perinatal deaths
why is prenatal diagnosis helpful?
*M.O.P.P.
- management
- outcome of determination
- plan for possible pregnancy/newborn complications
- decide whether to proceed w/ pregnancy
what are the different techniques used for prenatal diagnosis?
*M.A.C.C.U.
- Maternal serum markers
- Amniocentesis
- Chorionic villus sampling
- Codocentesis
- Ultrasonography
MSAFP
*Maternal Alpha Fetoprotein
Chorionic Villi Sampling
*CVS
- an TV US directed biopsy of the placenta
- performed b/w 9-12 wks gestations
-
What is the role of the sonographer during OB?
assess:
- gestational age
- viability
- # of gestations
-trophoblast location
Cordodentesis
*aka PUBS (oercutaneous umbilical cord blood sampling)
- blood sample obtained from fetal umbilical vein post 17 wks gestation
- can also transfuse fetus w/ RBCs through umbilical vein
Aneuploidy
abnormal number of whole chromosomes
Turner Syndrome
*aka monosomy X
- fetus has only one sex chromosome
- ALWAYS FEMALE
How are syndromes clinically id’d?
results from multiple defects present
Trisomy 21
- what is it?
- risk factors
- diagnosis
*aka Down Syndrome
- 3 copies of chromosome 21
- risks: maternal age, low levels of AFP, PAPP-A, and uE3
- rule out: amniocentesis
Trisomy 21
- US appearance
- > 3mm nuchal translucency
- > 6mm nuchal fold
-echogenic cardiac focus - absent nasal bones
- brachycephaly
- duodenal atresia (double bubble sign)
Trisomy 18
- what is it?
- risk factors
- diagnosis
*aka Edward’s Syndrome
- extra of chromosome 18
- most likely spont. aborts
- 1:3 girls:boys
Trisomy 18
- US appearance
- CHD
- IUGR
- single umbilical artery, small placenta
- choroid plexus cysts
- rocker bottom feet
- small chin
- omphalocele
- diaphragmatic hernia
Trisomy 13
- what is it?
- risk factors
- diagnosis
*aka Patau’s Syndrome
- 1:5000 births
- not compatible w/ life
Trisomy 13
- US appearance
- holoprosencephaly, midline defect
- cleft lip/palate
- cyclopia
- VSD
- extra fingers/toes
- omphalocele
- small chin
agenesis of corpus callosum
Triploidy
- complete extra set of chromosomes; 69 chromosomes
- two sperms fertilized one egg
- assoc. w/ partial molar pregnancy
- high HCG & AFP levels
Triploidy
- US appearance
- IUGR
- 69 XXX: early-asymmetrical IUGR
- 69 XXY: symmetrical IUGR
- congenital heart disease
- oligohydramnios
- CNS malformations
- syndactyly
- placentomegaly
Noonan Syndrome
- type of dwarfism
- prevents normal dev. in various parts of the body
- cystic hygroma, short neck, stature
Fetal Alcohol Syndrome
mom binge drinks during pregnancy
- assoc. w/ IUGR, heart abnormalities
IUGR
decreased fetal growth, 10th percentile
Est. fetal weight
incorporates:
- BPD
- HC
- AC
- FL
Symmetrical IUGR
- ALL measurements are small
- 25-30% of IUGR
- US: small for dates, adv. placenta grade but decreased thickness <1.5 cm, high resistance flow in umbilical, cerebral, UT a., low biophysical profile (BPP)
Asymmestrical IUGR
- 70-75% of IUGR cases
- ## caused by placental insuffiency
BPP
*biophysical profile
- measures fetal health during pregnancy
- done in final trimester if normal
- if high risk, done 32-34 wks, possibly 2x a wk
What are the parameters of BPP?
- non-stress test
- fetal breathing movements
- fetal body movements
- fetal muscle tone
- amniotic fluid volume
