T2 L13 Prenatal screening Flashcards
What is screening?
Identifies apparently healthy people who may be at increased risk of a disease or condition, enabling earlier treatment or informed decisions
What is the 10-14 week scan for?
Viability Accurate dating Detect multiple pregnancies Diagnose structural abnormality Screen for chromosomal conditions
What is the main determinant of foetal outcome in a multiple pregnancy?
Chorionicity
What does it mean for the babies if there is a T-sign on the U/S?
Identical twins
Babies share a placenta
What does it mean for the babies if there is a lambda sign on the U/S?
Dichorionic
There is an extension of placental tissue into base of intertwin membrane
Give examples of structural abnormalities diagnosed on the 10-14 week scan
Spina bifida
Anencephaly
Exomphalos & gastroschisis
Bladder outflow obstruction
What does a diagnostic test do?
Gives definitive information on the foetal chromosomes by confirming the presence of an extra chromosome or the absence of a chromosome
What are the types of diagnostic tests?
Chorionic villus sampling
Amniocentesis
What is CVS carried out from?
11 weeks
When is amniocentesis carried out from?
15 weeks
How is the chance of a baby having trisomy 21 and/or trisomy 13/18 calculated from the combined screening test?
Maternal age + nuchal translucency + PAPPA BhCG
What are some influencing factors for combined screening?
Maternal age Gestational age Ethnicity Smoking IVF Multiple pregnancy Weight Diabetes Past history of chromosome abnormality Foetal sex Analytical imprecision.
How are results of the combined screening delivered if there is a high risk?
Phoned within 3 working days
How are the results of the combined screening delivered if there is low risk?
Letter within 2 weeks
What is the detection rate for combined screening?
82%