CVS is designed to test for certain genetic disorders during pregnancy, much like an amniocentesis, with the exception that it can be performed as much as one month earlier, a great deal of time when you are talking about fetal development. If your doctor recommends this test, it is very important that you understand the risks, benefits and ramifications before you agree - the test is always elective.

Who should get the test done? A doctor will often recommend a CVS if:

• You will be over the age of 35 at the time of delivery because of the increased risk of chromosomal conditions. For example, a woman's risk of delivering a baby with Down Syndrome is about 1 in 1150 when she's 25 years old, but when she is 35, this jumps to 1 in 300, and at 45 years of age it can be as high as 1 in 32. About half the women that elect for this test do so because of age.
  
• You have previously delivered a child with a chromosomal problem or birth defect. Although it is not absolute, this can be evidence that you and/or the baby's other parent is a carrier for a chromosomal condition.
  
• If anyone in either parent's family history has had or shown symptoms of a chromosomal condition. Many times a family will not be aware someone in their ranks is suffering from a genetic condition, but the screener may ask you questions like has anyone in your family been unusually tall, short, had a child who has died in early childhood, had learning disbilities or suffered unusually frequent nosebleeds. These in themselves may not be of concern, but sometimes coupled with other indicatiors can be evidence of a possible chromosomal condition.
  
• If you are from an ethnic background at especially high risk for or have a high chance of being a carrier for a chromosomal condition. For instance, people of West African descent have a 1 in 6 chance of being a carrier for sickle cell disease, those of Asian descent have a 1 in 20 risk of being a carrier for alpha thalassemia. Being a carrier does not mean you will pass that gene along nor does it mean your children will have that disease, but if you and the baby's other parent are both carriers, the risks to our baby can increase.
• You know that having the test done will effect any future decisions. Treatment for certain disorders can be attempted in the womb (congenital adrenal hyperplasia for instance, which can be treated with hormones in the first trimester, eliminating the need for surgery after birth), or perhaps you just want to be better prepared for challenges you may have to face (a more specialized hospital for the delivery, or searching out support groups, for example). Some people choose to not to bring the pregnancy to term after finding out the results of a genetic screening. But if the information gleaned from genetic testing will not affect how you handle your pregnancy, or if you are very concerned about the risks to the baby there is no reason to take the test.

What do they test for? - Each person is ideally made up from two sets of the same type of chromosomes, one set from the mother and one set from the father. A CVS can determine with 95% -99% accuracy conditions that result from having either too many or too few of each, and/or a problem with the banding of them. If you have a concern about a particular genetic trait in your family (as opposed to a chromosomal one - chromosomes are composed of long strings of genes) you can talk to the doctor about it ahead of time, and the lab will save some of the sample from the test for more specific analysis later on. They cannot examine each individual gene because there are just too many. Among others, some things they test for are:

• Sickle cell disease
• Beta Thalassemia (Cooley's anemia)
• Alpha Thalassemia
• Cystic Fibrosis
• Tay Sachs disease
• Down's Syndrome
• Canavan
• Niemann Pick
• Fanconi Anemia
• Bloom
• Caucher
• Fragile X
• and of course gender, if you choose to know
• can be used for paternity testing as well
• does not test for neural tube defects

How is the test done? - A small sample of the tiny fingerlike projections on the placenta are removed. These have the same genetic makeup as the baby. These are then sent to the lab, cultured and matured into a large enough sample for them to use. They then extract 10 to 15 individual cells (to make sure they are not examining an anomaly) which they examine under a microscope, sort the chromosomes of and compare the banding of. They will then analyze the results and give you a call. If the test is inconclusive (some cell lines are normal and some are abnormal - called mosaicism -  about a 1% chance) or if a problem is detected, they may recommend an amniocentesis to confirm.
   
What is the difference between this and an amniocentesis? - An amniocentesis analyzes the makeup of the amniotic fluid instead of the villi. It is very similar, and tests for almost the same things. The main differences are that an amniocentesis is a little more accurate (from 1% to 5% more accurate) and is done about a month later (at 15 to 18 weeks as opposed to a CVS at 11-12 weeks), a long time in the development of a fetus.

How do I choose where to take the test? - Most doctors will recommend you to a perinatal specialist for a CVS. It has been determined that many of the risk factors associated with the test are directly related to the physician's experience and how far along the pregnancy is. Most complications arise when the test is performed at less than 10 weeks of pregnancy as determined by ultrasound, so make sure to ask when is the earliest that doctor is comfortable performing the test, and how many per year he or she performs. If you do not like the answers or the doctor sounds inexperienced (I have been given a figure of less than 50 per year as a gauge) you may want to scout around for another doctor or wait for an amnio.

What are the risks?

• Miscarriage, about a 0.5% to 1% risk. Although the numbers for this are a little inflated, since many times a fetus with a chromosomal abnormality will be miscarried anyway (if they are lacking the proper genes for a certain stage of fetal development, they will not live and the body will miscarry). For an amnio the risk of miscarriage is between 0.25% to 0.5%, partially because the chances of miscarrying a month earlier are greater. These numbers are also affected by the doctor's experience level.
  
• Missing fingers or toes, although this has also been dertermined to be directly realted to the experience level of the doctor and the developmental age of the baby. This risk does not seem to be an issue if the test is done after the 11th week of pregnancy.

What will happen to me in the doctor's office and will it hurt?

1. Before scheduling, you should have a blood workup done to determine if you are Rh negative in which case you may need follow up Rhogam injections. Talk to your doctor if this is the case. Other than that, you do not need to fast or anything like that prior to the test.
   
2. You will need to go to the doctor with someone who will drive you home as it is not recommended that you drive after the procedure. Preferably, the baby's father, since you will be asked a number of questions about his family history. Try to schedule the test for a Friday since you will need to take things easy for a day or two afterwards, and schedule it early enough in the day so the doctor has time to get the sample to the lab before it closes (preserved samples are never quite as good). Wear loose fitting clothes both so that you are comfortable riding home and our doctor just had me expose my abdomen instead of getting all undressed, since my clothes were accomodating.
   
3. When you arrive at the doctor's office, you will probably have to fill out quite a bit of paperwork and read a number of forms related to the test. Then most doctors will have you assigned to a genetic counselor to assess your family history and risk factors and go over what genetic screening is all about. For us this was someone from the lab, and the session took about 30 minutes. If at any time you change your mind about having the test, you can opt out.
   
4. Once the doctor calls you in, they will do an ultrasound to determine whether the baby is developed enough to safely perform the test, if the placenta is thick enough to get a good sample and where the thickest part is so the doctor knows from where to take the sample and whether to do the test abdominally or cervically. (My placenta was too spread out and thin so we had to postpone the test for a week.) They will gently poke around on your abdomen to find the best place to start. This is aso a chance for you to see the baby and listen to the heartbeat again. Go ahead and ask for pictures. They will usually accomodate.
   
5. If the placenta is thickest on the top they will perform the test abdominally (how they did mine, mine was just below where my tummy pooches out). They will ask you to relax your hands on your chest, then swab the area with disinfectant. I had had a slight cold that week, but they told me as long as I wasn't coughing, sneezing or had a fever, I was all right. They want to avoid any muscle contractions while the test is being done. (Tell whoever comes with you not to make any jokes during the test as well.) Then they will give you a small local anesthetic. It just feels like a pinch.
6. For the next part, a technician will work the ultrasound so the doctor can see what's going on. If you aren't so hardy (I'm not) resist the urge to watch the screen. Close your eyes and think of something else instead or bring an iPod and put in some relaxing music and one ear phone so you can still hear the doctor if he talks to you. (This works at the dentist too.)
7. In the numbed area, the doctor will insert what looks like a needle but what is really a tube or catheter. This will not go all the way into your uterus, but just through the first part of your abdomen. This feels like some sudden pressure and is uncomfortable but doesn't really hurt.
8. Then they will thread a longer, thinner needle through the catheter and into the abdomen. This feels like more sudden pressure and a short bit of pain as it enters the uterus, but it is over very quickly, like an injection.
9. I had my eyes closed, but my husband watched the whole thing and said that although it was kind of creepy, the needle never even got close to the baby, something I had been a little worried about.
10. Then the doctor will ask you to take a deep breath and they will take out the catheter. This just felt weird but it didn't hurt. They will swab you off and you can go home. One note - the disinfectant was a brownish red color, so when I opened my eyes and saw the stained gauze it looked a little like blood, but it wasn't.
11. I didn't have transcervical, but I believe the basic procedure is the same, only since they are going in through your cervix, you will probably be propped up like when you have a pap smear done, and they will approach it from that angle.

How long does it take? - The genetic counseling took about 30-35 min, the test about 30 min, add in paperwork and waiting and you are talking maybe 2-3 hours. Our doctor's office was willing to fax us the papers ahead of time so we could fill them out the night before and miss less work.

What about afterwards?

• If you have transabdominal, refrain from strenuous activity for 48 hrs and intercourse for 1 week after the test.
• If you have transcervical, refrain from strenuous activity, intercourse, tub baths, jacuzzis or tampon use for 2 weeks. You may experience some vaginal bleeding (like a light period) or delayed bleeding of old blood.
• You may feel light cramping for a day or two (I felt some tightness and a weird sort of queasy feeling but it went away the next day).
• Contact your doctor right away if you have severe cramping or bleeding, abdominal pain or fever or fluid leakage.
• Eating and drinking are fine right after the test.

Is it covered by medical insurance? - In the United States, this test is considered a surgical procedure, and most doctor's offices bill it as such, so it will most likely be aplied toward your deductible. Most insurance companies treat this test in the same way they treat an amnio, but call them ahead of time to make sure.

Other sources:

babycenter - CVS
march of dimes - down syndrome
medline plus - CVS with pictures
APA - CVS


Forgive me if this article is a bit long, but before I had this test done I had to run all over the place trying to get all my questions answered, and still many of the things I wanted to know weren't cleared up. I have put most of what I was concerned about in this article as possible.