1.8 Prenatal Testing Flashcards
What happens following a positive pregnancy test
Booked into antenatal care to see a midwife
Much a, scan at 10-14 weeks
Mid trimester anomaly scan 20-22 weeks
Aims of nuchal scan
Accurately date the pregnancy
Diagnose multiple pregnancy
Diagnose major fetal abnormalities
Diagnose early miscarriage
Assess chance of Down syndrome and other chromosomal abnormalities
When is the nuchal scan
10-14 weeks gestation
When is the mid trimester anomaly scan
20-22 weeks gestation
Nuchal translucency (NT)
Thickness of fluid at back of fetal neck
More than 3mm can indicate chromosomal abnormalities
What is nuchal translucency combined with
Maternal blood markers and age
How does increased NT look
Neck is wider looks flat (no curve)
Sim of anomaly scan
Look for structural anomalies
Heart brain spinal cord face kidney abdomen
Measure length of bones
When is prenatal testing offered
Following abnormal findings at nuchal or anomaly scan
Results of combined tests for chomosomal abnormalities
Previous pregnancy affected with a condition
Family Hx of a genetic condition
Aims of prenatal testing
Inform and prepare parents for birth of an affected baby
Manage remainder of the pregnancy
Prepare for complication during and after birth
Allow termination of an affected fetus
Non invasive prenatal diagnosis
Analyses the dna fragments present in maternal plasma during pregnancy
NIPD fetal sexing
Offered when there is an x linked condition (e.g. DMD)
Tests detect SRY gene on Y chromosome to determine male or female fetus
SRY gene
Sex determining region
If male from NIPD fetal sexing
Go onto prenatal testing (x linked)
If female from nipd fetal sexing
No invasive test required
