The positive blood test
Imagine this scenario: Dr. Schultz is the same OB/GYN Layla had when she was pregnant with her daughter, so she’s comfortable with him by this point. Layla appreciates his compassion and excitement for her new pregnancy every time she’s in the office, joking she’ll name her first son after him. So when Dr. Schultz calls her back into his office for her test results with a stern and almost upset tone, she finds herself on high alert. Immediately upon walking into his office, he says one of her blood tests came back positive, and he’s so sorry to report her baby has Down syndrome.
Wait, a minute. What blood test?
There are lots of blood tests that are performed during pregnancy. Often, the tests check to make sure the mother is healthy throughout the pregnancy. However, there are some blood tests that are assessing the chance the baby could have Down syndrome or another chromosomal condition.
There is no blood test a pregnant person can have done which diagnoses their baby with Down syndrome at this time. The only way to diagnose a chromosomal condition like Down syndrome is through prenatal diagnosis (like chorionic villi sampling or amniocentesis) during pregnancy or to wait until after pregnancy and perform a blood test on the baby.
There are a few blood tests that are offered during pregnancy to assess the chance a baby could have Down syndrome and other chromosomal conditions. There are two categories of blood tests.
Multiple Marker Screening: evaluates hormone levels in the pregnant person’s bloodstream. The goal is to look for patterns within those hormones to see if they resemble patterns that have been seen in pregnancies that have chromosomal conditions.
Non-invasive prenatal testing (NIPT), non-invasive prenatal screening (NIPS), cell-free DNA testing (cf-DNA), ect. (many names to describe this one): evaluates placental DNA fragments in a pregnant person’s bloodstream and looks to see if there is too much or too little of the DNA in the bloodstream. Too much DNA could mean an extra chromosome since chromosomes are made up of DNA whereas too little DNA could mean a missing chromosome.
The results can be “positive”, but really this means there is an increased chance to have a baby with a chromosomal condition. These tests cannot diagnose a baby with the chromosomal condition. The reason the tests are performed is to let people know if they should more seriously consider the possibility that their baby could have one of these conditions. If someone receive a positive result, then they may be offered an amniocentesis to confirm or exclude whether the baby has that condition. If someone does not feel comfortable with the risks of an amniocentesis, then they can wait until after their pregnancy to have confirmation testing. Either of those options are totally okay, as long as that is what the person is most comfortable with.
Some people want to know if their baby could be at an increased risk to have a chromosomal condition and would like to know if they should consider an amniocentesis. They seek this information, so they are able to make pregnancy decisions like adoption, termination of the pregnancy, or to know for certain so they are better able to plan for their baby that has a chromosomal condition. For some chromosomal conditions like Trisomy 13, there is a higher chance the baby will pass away during or soon after pregnancy. For this condition, some people cherish the time they have left with their baby and are glad they knew the baby's diagnosis ahead of time.
Other people feel anxious thinking about being in this type of situation and know they wouldn’t change their pregnancy decision despite any condition their baby may have. They may think it is helpful to know if there is something unexpected going on; however, the risk of amniocentesis is not worth the information. They also do not want the stress of a positive test without being able to do confirmation testing until after the baby is born.
Often, these blood tests are being lumped in with routine tests. Some people feel this testing should be routine, yet every pregnancy is personal. Everyone has his or her own reason for why they may or may not want to know this information. Every reason is valid. It is important to be given the opportunity to choose or not choose these blood tests. Everyone has the right to decide what they are and aren’t tested for.
As always, please consult your physician or care providers as to what testing aligns best with your values and health.
* This blog constitutes general information about genetic testing and medical screening. This blog does not offer or provide medical advice or diagnosis, and nothing in this blog/webinar should be construed as medical advice or diagnosis. Do not rely on the information in this blog/webinar to make medical management decisions. Please consult with a medical professional before making those decisions. Do not delay in seeking professional medical advice if you think you have a medical concern. Do not disregard professional medical advice based on any information received in this blog.
