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Prenatal Diagnostic Procedures

Prenatal diagnostic procedures include amniocentesis and chorionic villus sampling.
About

Prenatal Diagnostic Procedures

The Advanced Maternal Age (AMA) program is an option if you will be 40 years or older at the time of your delivery. Your physician or midwife may refer you to our Program for Prenatal Diagnostic Procedures.

Prenatal diagnostic procedures include:
  • Amniocentesis
  • Chorionic Villus Sampling

BC Women's is the main referral centre in BC for the prenatal diagnosis of genetic disorders and birth defects. Diagnostic procedures are performed in cooperation with the Medical Genetics Program. Common procedures include:

  • Fetal Diagnosis and Treatment: When a prenatal ultrasound identifies possible or actual genetic birth defects in a fetus, experts from Medical Genetics, Maternal/Fetal Medicine, Ultrasound and pediatrics work together to plan care.
  • Talk to your doctor or midwife about your need for any of these services
  • pre-pregnancy counselling
Amniocentesis

Amniocentesis involves removing a small amount of amniotic fluid for testing in the lab. This test can be done after the 15th week of pregnancy. 

Our video will explain the procedure and answer many questions.

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When do I come to the hospital?

Your doctor or midwife will book your test. If you have been booked at Women’s Diagnostic Ambulatory Program, you will receive a letter in the mail telling you when to come to the hospital.

You should have a light meal before coming to the hospital. No other special preparation is necessary.

Who will do my procedure?

A doctor who has completed special training in this procedure will perform your amniocentesis. A nurse and a sonographer (ultrasound technician) will be assisting. 

Who should come with me?

It is advisable that you not drive yourself, or take public transportation (bus) after the test.

For this reason, we recommend that your partner, or another person of your choosing, accompany you for your test. If they do not wish to view the actual procedure, they may wait in the lobby, or sit just outside the procedure room. If you have to come alone, we recommend taking a taxi home, if possible.
 
Another adult must accompany children in case they need to be taken out of the procedure room.

What will happen?

Before having your test, a nurse will answer your questions and will obtain your written consent. You will receive information to take home about what to expect after your test.
 
It is not necessary for you to change your clothes. Wear something loose and comfortable that can be slipped down below your hips easily. Towels are used to help maintain your privacy and to protect your clothing.
 
Ultrasound is used to locate the baby and placenta. The baby’s heart rate is recorded before (and after) the procedure. Some measurements are taken to check the baby’s growth and to confirm your weeks of pregnancy. With the ultrasound picture on the screen, the doctor finds the safest and easiest place to insert the needle. An antiseptic solution is used to clean the skin. (The pink stain on your skin will wear off in a few days.) The needle is carefully guided to the selected spot and the small sample of fluid is withdrawn through the needle.
 
During the test, you may experience some cramping and a slight sensation of pressure. Most women find it no worse than having a blood test taken from their arm.

What happens after my procedure?

 You do not need to stay in the hospital following your test.
 
We recommend that you rest for the next 24 hours. You do not have to go to bed; resting on the couch or in a reclining chair is fine. Avoid heavy lifting and use the time to relax with a favourite book, video, etc. If you need a note to be off work, the doctor who does your procedure will sign it for you.
 
If you have come from outside Vancouver, you may want to stay somewhere overnight. If this is not an option for you, take it easy (e.g., use the elevator on the ferry or the cart to get to your departure gate at the airport, take stretch and bathroom breaks if you are driving a longer distance).
 
We will provide you with written information about what to watch for and how to contact us if you have any concerns. Mild cramping is the most common side effect, and it should go away over the next twenty-four hours.

Read here for more information about Amniocentesis

Chorionic Villus Sampling
When do I come to the hospital?

CVS is requested much less often than amniocentesis. At BC Women’s, CVS is provided only on Wednesday mornings.
 
When your doctor or midwife requests this test, we will put your name on a waiting list. We will contact you about a week before the test. If there is no available CVS appointment, you will be offered an appointment for amniocentesis. 
 
You should have a light meal before coming to the hospital. No other special preparation is necessary.

Who will do my procedure?

A doctor who has completed special training in this procedure will do your CVS. A nurse and a sonographer (ultrasound technician) will be assisting.

Who should come with me?

We advise you to not drive yourself or take public transportation (bus) after the test. For this reason, we recommend that your partner, or another person of your choosing, accompany you for your test. You may choose to have that person in the procedure room with you, or, he or she may wait in the lobby, or sit just outside the procedure room. If you have no one to come with you, we recommend that you take a taxi home.
 
NB. Another adult must accompany children. They may view the baby on ultrasound prior to the procedure, and then wait outside during the test.

What will happen?

Before having your test, a nurse will review the procedure with you and make sure that you are aware of the available options. We will answer any of your questions. She will then obtain your written consent. You will receive information to take home about what to expect after your test.

Ultrasound is used to locate the baby and placenta and to guide during the procedure. The fetus’ heart rate is recorded before (and after) the procedure and some measurements are taken to confirm the number of weeks of pregnancy.
 
The location of the placenta will determine whether it is possible to do the CVS and the best route for obtaining the sample. 
 
Prior to the test, the area will be cleaned with an antibacterial solution.

  • Vaginal route: the doctor will insert a speculum (like when you have a PAP test done), and using a small instrument, take a small sample from the placenta.
  • Abdominal: the doctor will insert a fine needle through the abdomen into the placenta, and take a small sample. You may experience some cramping and a slight sensation of pressure.

If it is not possible to do the CVS, we will schedule you for an amniocentesis at the earliest possible appointment, after you have reached 15 weeks of pregnancy.

What happens after my procedure?

You do not need to stay in the hospital following your test.
 
We recommend that you rest for the next 24 hours. You do not have to go to bed. Resting on the couch or in a reclining chair is fine. Avoid heavy lifting and use the time to relax with a favourite book, video, etc. If you need a note to be off work, the doctor who does your procedure will sign this for you.
 
If you have come from outside the Vancouver area, you may want to consider staying somewhere overnight. If this is not an option for you, “take it easy” (e.g., use the elevator on the ferry or the cart to get to your departure gate at the airport, stretch and take bathroom breaks if you are driving a longer distance).
 
You will receive written information about what to watch for and how to contact us if you have any concerns. Mild cramping is the most common side effect, and should go away over the next 24 hours.

Read here for more information about Chorionic Villus Sampling.

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