We also get a level of the alpha-fetoprotein, which is a protein produced by the fetal liver, and will be elevated if there's an opening in the fetus. Most commonly, we talk about neural tube defect, which is an opening along the spine, but you could have an opening in the front, too, where there's stomach or intestines out -- any type of opening will increase the level of AFP, we call it.
The fluid itself, not the cells, we can measure the alpha-fetoprotein level right away and get an answer regarding that. But the chromosomes and any type of genetic testing that involves DNA, we need to grow the cells in the laboratory.
Question: How long does it take to get definitive results with amniocentesis?
Answer: It takes about, depending again on the laboratory, about a week to 10 days to get the results of the chromosomes. If we have to do some specialized testing, it'll take us that long to grow the cells and then we have to send them off into a very specialized laboratory. Sometimes only one laboratory in the country or one laboratory in the world does the testing.
So if we have to do DNA testing, it takes a little bit longer, maybe a few days longer, maybe even a couple of weeks longer. But the most common type of testing, the chromosomes, we should have results within 10 days.
Question: Can you rule out most birth problems or birth defects with amniocentesis if you get clean results? Is that kind of smooth sailing for the rest of the pregnancy?
Answer: That is a great question, because most patients think normal amniocentesis, normal baby. We talk about background risk of 3% of all types of birth defects. Only one small portion of that are chromosomal problems. So we're not ruling out everything by doing that testing. We're ruling out things like Down syndrome and other chromosomal problems, and we're only looking at specific genetic disorders if we know the couple's at risk for them. It's not done routinely.
Other types of birth defects will, however, be picked up by the targeted ultrasound. But all birth defects will not be picked up by the amniocentesis.
Question: What kind of counseling or conversations do you have with your patients? Since you're talking about the second trimester, they're well along in their pregnancy and they have to make a hard decision about what to do with this baby. It's got to be tough in the second trimester.
Answer: It is a much more difficult situation. Many times the mothers are aware of fetal movement. They're beginning to show. Others know that they're pregnant. And the diagnosis in a sense is relatively late, although it's still in the first half of the pregnancy or the second trimester. It does make making a decision that much more difficult, but again, the options are the same. Either continue with the pregnancy, with the appropriate workup and other sub-specialists who need to be involved becoming involved, and any other diagnostic testing that needs to be done being done. Or a decision is made to terminate the pregnancy.
Here, there are several techniques or methods that may be used to accomplish that. And we usually have some conversation about what the various methods are.
Question: Do you help prepare for a delivery, for perhaps a problem delivery, or are there things to sort of help it along? Answer: Certainly we do. We talk to the parents about what to expect when the baby is born. We have them meet with the neonatologist. They're specialists who deal with newborn babies that have problems, or premature babies. If the baby's going to have a heart defect, they meet with a cardiologist and a cardiac surgeon. If there's an open spine defect, they might meet with a neurosurgeon, or doctors that specialize in taking care of those types of children.
Depending on the problem that we see, we have the parents meet with the specialists they need to meet with, and actually we have them go into the neonatal intensive care unit to see what it's like to have a baby there.
This is a chance to look around, and talk to other parents, so that they will be ready to have a child with special needs. And we let them know what that's like to have a child. We might introduce them to other parents that have a similarly affected child. They might even go to some of the special schools that their child might need.