1st & 2nd Trimester Screening
Screening tests DO NOT diagnose a problem; they only signal that further testing should be done.
Most babies are born with a serious mental or physical handicap. The First Trimester Screening is a non-invasive evaluation in one visit that combines maternal blood screening tests with an ultrasound of the unborn baby (fetus)
To identify the risk for specific chromosomal abnormalities, such as: Down’s syndrome (Trisomy-21) and Edwards Syndrome (Trisomy-18). It is more common with older mother, but can occur whatever the age of the mother.
About 85% of affected fetuses are detected this way.
In Addition 5% of normal fetuses may be thought to be affected till further tests show this is not to be true.
THE BLOOD SCREEN.
This is taken the same way as the other blood tests, most likely by your named nurse. The blood screen measures two pregnancy related hormones: B-hCG and PAPP-A.
THE ULTRASOUND:
The ultrasound evaluation measured nuchal translucency (fluid beneath the skin, at the bac of the baby’s neck)
Also includes an evaluation of fetal growth.
WHEN IS THE FIRST TRIMESTER SCREEN PERFORMED?
It is necessary to be performed between 11th and 13th week of pregnancy.
THE RESULTS:
Can take up to a week to come.
They will be in the form of a risk factor ( for example 1/250, 1/1300). This means that your baby has this chance of being abnormal. It is not a yes or no result.
Abnormal test results warrant additional invasive testing such as amniocentesis or chorionic villous sampling for making a diagnosis.
Performing further testing allows you to confirm a diagnosis and then provides you with certain opportunities.
*pursue in potenrial interventions that may exist (i.e. fetal surgery for spina fibida)
*begin planning for a child with special needs.
*make a decision about carrying the child term
Some individuals or couples may elect not to pursue testing or additional testing.
Its important to realize that a positive result does not equate to having an abnormality, but rather serves a prompt to discuss further testing.
ACMG recommends informing all pregnanct women of the availability of the expanded use of non-invasive prenatal testing (NIPT) to screen for clinically relevant CNVs(microdeletions) and suggest specific discussion points that should be covered during this conversation.
