Having your baby or child diagnosed with SMA is a traumatic experience and it will inevitably have a major impact on your thinking about having future children.
There are a number of options open to you, some or all of which you may wish to consider. There are no right or wrong decisions to be made and you need to reach a conclusion that is right for you. There is also no need to rush into a decision or to feel unable to change your mind.
This Fact Sheet deals with the issues around Chorionic Villus Sampling (CVS), but you may choose to have no further children: to have Preimplantation genetic diagnosis (PGD) or to have further children without any tests at all. We have a separate Fact Sheet on PGD.
What is a CVS?
A CVS is usually performed at about 10-12 weeks into the pregnancy.
At an early stage in pregnancy, the embryo forms itself into two parts: one becoming the developing baby and the other developing into the placenta (afterbirth). The part that forms the placenta starts out as finger-like sections called Chorionic Villi, these burrow into the wall of the womb to come close to the mother's blood vessels. The division of the original fertilised egg forms these Villi and so they have exactly the same DNA as the embryo, including any genetic abnormality. Any defect in one will be present in the other.
You will normally be asked to travel to a regional centre for the CVS. This is usually linked to the Genetics Department where your DNA tests will have been carried out. The test will usually be performed by a doctor with the help of a nurse and radiographer. Initially an ultrasound scan will be done to measure and check the baby and locate the position of the placenta. Providing the doctor is happy with the scan result, the test will take place immediately following the scan. In some cases you may be able to watch the procedure on a separate monitor.
In a CVS, a small sample of Chorionic Villi is obtained either by passing a thin needle through the wall of the abdomen (transabdominal), or by passing a small tube through the vagina and neck of the womb (transcervical). The instrument is moved to the site of the placenta under the guidance of ultrasound scanning and a fragment of the tissue is then gently sucked up through the needle. It is important to be able to see the tip of the instrument using ultrasound to avoid making a hole in the amniotic sac (the protective sac that cushions the baby with fluid as it grows). The Cytogeneticist from the laboratory may be in the department to examine the quantity of the tissue obtained. Sometimes it is necessary to repeat the procedure more than once to obtain enough tissue.
What is it like?
The test usually takes between 10 and 20 minutes and most women describe it as being uncomfortable rather than painful. Some centres may offer a local anaesthetic as part of the procedure. You can usually go home as soon as the test is finished. It is sensible to travel by car where possible and to have someone accompany you. It is advisable to rest for the remainder of the day and perhaps the following day. It is not usually necessary to go to bed, but you should avoid any strenuous exercise.
Some women experience cramps, similar to period pains, following the procedure, which may last for one or two days. There may also be some slight "spotting" or vaginal bleeding, but everything usually settles down within a day or two. There are usually no other after-effects following a normal CVS procedure. If high fever, excess bleeding or vaginal discharge occurs, then medical advice should be sought.
What risks are there with a CVS?
There is a slightly increased risk of miscarriage following a CVS. The miscarriage rate following CVS is thought to be between 1 in 50 to 1 in 100. This figure includes all pregnancies lost up to 24 weeks of pregnancy in women who have had a CVS. However this needs to be weighed against the high natural risk of miscarriage during the first trimester: as many as 1 in 4 pregnancies.
Other factors can influence foetal loss rates adversely in CVS, and these include the location of the placenta in the fundus (the uppermost segment of the uterus) as opposed to the side wall of the uterus (which is the normal site), the number of catheter passages during the procedure, and any history of bleeding during the pregnancy.
It is also possible for infection to occur.
In clinical trials an association has been made between CVS and a slight increased risk for limb abnormalities in the foetus (such as short fingers or missing toes) Brumback B A, Holmes L B, Ryan L M. Adverse effects of Chorionic villus sampling: a meta-analysis. Statistics in medicine, 1999; 18(16): 2163-2175.
When will I get the results?
The results will normally be available in 7-10 days. Your Doctor or Genetics Nurse will discuss with you how the test results will be communicated to you and this is something you may want to talk about prior to the test.
A Personal Perspective
Mother of a Type I baby: "I found that the genetics nurse was very helpful in liasing between the laboratory, the hospital and us. It's worth asking to have a dating scan at around 8 weeks, as this will confirm the dates are approximately correct and reduce the possibility of being disappointed on the arranged date of the CVS test. My consultant didn't use a local anaesthetic, as some do, and the first CVS test was quite painful. The second one was merely uncomfortable in comparison - every pregnancy is different.
The CVS results took approximately a week. When we had a bad CVS result it was devastating, but it was still in a way a relief that the waiting was over and we could get on with trying again. Nothing is as bad as losing a child and this enabled me to go through with a termination, knowing that I wouldn't have to watch another baby die.
In time, we finally had a good CVS result. I was in shock to start with, even though my partner was celebrating as soon as we heard. 6 months later, we got the child we'd been waiting for. Although it will never take away the pain of losing our first born, our new baby has brought joy and happiness back into our lives." | 
