Your Ultrasound Examination What is ultrasound? Ultrasound is high frequency sound (much higher than humans can hear). The examination may sometimes be called a “scan” or a “sonar”. The sound waves pass into the body from an ultrasound transducer (a metal crystal) and the sound is reflected off the internal organs. The ultrasound machine changes the returning echoes (sound waves) into visible images and displays them on the television screen. Images of both normal and abnormal internal organs displayed on the screen can be recorded for later review. Is ultrasound safe? Diagnostic Ultrasound has been in clinical use since the late 1950’s. The Australasian Society for Ultrasound in Medicine Statement includes: There is no convincing evidence that diagnostic ultrasound causes adverse health affects in human patients. ASUM however acknowledges that epidemiology data has several limitations. More research is always needed. The results of follow-up studies have not demonstrated adverse fetal outcomes from ultrasound exposure. Good practice, however, limits ultrasound exposure to situations where clinical benefit is anticipated. Doppler Imaging (which includes colour) usually involves higher outputs; particular care is taken to minimise exposure.

How is an ultrasound examination performed?
Ultrasound waves are sent out from a transducer which is usually moved over the skin of the abdomen. Gel must be spread on the skin before the scan to allow the ultrasound waves to pass from the transducer into the body. There is no pain or other sensation from the ultrasound waves to either the person having the scan or the fetus. To obtain good views, at times some pressure has to be applied to the transducer, but there is usually no more than mild discomfort.

The ultrasound examination may also be performed by placing a small transducer into the vagina. This transducer is narrow, narrower than a vaginal speculum, and usually causes minimal discomfort. This is used particularly in the early weeks of pregnancy, or to examine the uterus and ovaries in a woman who is not pregnant. The advantages of a vaginal scan are that a full bladder is not required, and it can provide more accurate information in some situations. In pregnancy this examination cannot harm the fetus - the transducer does not go into the uterus. Between patients, the transducer is cleaned and disinfected to prevent cross infection, and a protective cover applied. The transducer is inserted by the examiner, or you may prefer to insert it yourself as you would a tampon. If you wish to have a third person in the room for a vaginal scan, please let us know.

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Is a full bladder needed?
With modern equipment a very full bladder is rarely required.

Please note:

• In general it is useful if you could ensure that there is a little urine in your bladder at the time of the examination.
• If we suggest a vaginal scan we will ask you to empty your bladder.
• A very full bladder may be required if you are either not pregnant or are in the early stages of pregnancy and you wish to avoid a vaginal scan.
• You may eat what you like before the examination.

Why is ultrasound used in pregnancy?
The most common reasons for your doctor to arrange an ultrasound examination during pregnancy are as follows:

• To calculate the due date,
• To see if there are twins,
• To determine if the pregnancy is continuing normally when there has been bleeding in early pregnancy,
• To check the position of the placenta if there has been bleeding late in pregnancy,
• To check the physical development of the fetus and as far as possible to make sure there are no abnormalities,
• To see if the fetus is growing normally

After the fourth month (18 weeks and onwards) better views are obtained of the fetal arms and legs, plus its organs, including the spine, stomach, heart and bladder. Many abnormalities, but not all, can be detected. While it is not possible to diagnose Down Syndrome with certainty using ultrasound, sometimes there are features seen on the scan which might raise a question of Down Syndrome.

The policy of the practice is to be open and honest with you - if there is a problem detected you can be sure you will be told. You will undoubtedly be impressed with the amount of fine detail visible with modern ultrasound equipment. However not all physical defects can be seen and no prenatal test can guarantee a ‘perfect’ baby.

What about ‘social’ ultrasound?
An ultrasound examination is performed only for valid medical reasons. All experts agree that it should not be performed merely for social reasons. When you come to our practice for a scan, however, we do everything we can to make the experience a pleasant one for you. Please tell us if you have any particular requests. We are happy to provide you with photos, a video, and if you wish to know the sex we will try to find out for you. You are welcome to bring friends and family but please be aware that children under 5 years rarely find the scan an enjoyable experience, and are best accompanied by another adult who can take them for a walk if they become restless.

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Can ultrasound help with gynaecological problems?
Women who are not pregnant may be referred for an ultrasound examination for a number of reasons such as:

• To try to determine the cause of pain in the lower abdomen or pelvis,
• If the gynaecologist finds a lump in the pelvis, a scan will often help to determine its nature,
• Abnormal vaginal bleeding, either before or after the menopause.
• To check why a woman may have had difficulty conceiving

Why scan during invasive procedures?
As ultrasound gives a continuous picture, it is of great assistance in guiding a needle into areas deep within the body. Thus procedures such as amniocentesis and chorionic villus sampling (CVS), which are used to diagnose chromosome problems including Down Syndrome, are performed while watching the needle with ultrasound. In patients who are not pregnant, fluid may be removed from cysts in the ovary; and in ‘In Vitro Fertilisation’ treatment, eggs are collected from the ovaries using ultrasound to guide the needle.

What do the pictures look like?
Ultrasound provides a picture of only one slice or section at a time. It is like looking at only one slice out of a loaf of bread. In this way pictures that are seen on the screen do not show the whole of the fetus at one time. A picture that shows the head and body is therefore unlikely to include also the arms and legs. During the examination, every attempt will be made to show you the relevant features on the screen. The way the fetus is lying and a number of other factors can influence the clarity of the ultrasound picture. You can be sure that the ultrasound equipment used for your examination is the very best available for the purpose.

Summary
Ultrasound scanning is a very important method of assessing pregnancies. It can diagnose many of the complications which occur during pregnancy and provides information that can be vital in determining when and how best to deliver a baby.

The use of ultrasound in non-pregnant women with pain, bleeding, or with a suspected lump in the pelvis can provide very valuable information and in some will help avoid the need for an operation. When you have an ultrasound examination, you should expect to be at the practice for approximately 1 hour. If you have any questions please ask. If you would like more written information, we have pamphlets on procedures, including amniocentesis, CVS and fetal blood sampling. More complete information is available in Lachlan’s book titled “Prenatal Diagnosis: Which Tests For My Unborn Baby?” (OUP), which we have available at a discounted price.

Finally, it is important to us that we provide you with the best possible medical service in a pleasant atmosphere - we would be delighted to hear any comments you have. We aim to provide the highest standard in women’s imaging and counselling.

Your Obstetrical Ultrasound Examination
An ultrasound examination may be requested for many clinical reasons at any stage of pregnancy, from the time you know you are pregnant to delivery. The information gained from the examination varies greatly with the stage of pregnancy. Your doctor will discuss scans with you.

Many women have a scan at 12-13 weeks; this is primarily to check for chromosome abnormalities such as Down syndrome, although many other abnormalities can be checked for at this time.

A second common time for an ultrasound examination is 18-20 weeks – this is primarily to check the physical development of the fetus. Other scans are carried out as indicated.

Common reasons for additional scans in early pregnancy include bleeding or pain. Common reasons later in pregnancy are to check the growth and wellbeing of the fetus. The following segment is set out according to the weeks of pregnancy so you can read the section that applies to you.

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Scans in the First 11 weeks
Indications: Common indications include pain, bleeding, to check the gestation and women who have had treatment for infertility.

What can be seen? The pregnancy sac becomes visible at about 4 ½ weeks after your last period began. ( In obstetrics we date pregnancies from the first day of the last period, not from the time of ovulation / conception).

6 weeks: The fetus and the heart beat can usually be identified.

9-10 weeks: You will start to see some of the structures such as arms and legs.

12-13 week Scan
This scan is widely offered to women in pregnancy. Its prime goal is as a check for chromosomal abnormality. Because so much information can be obtained at this early stage, it is a scan we have devoted particular attention to and we offer a number of special services to patients. These include:

1. We will have a discussion with you before the scan to determine what information you would like to receive.
   
   
2. The nuchal translucency, a measurement of the thickness of the soft tissues of the fetal neck, is used to estimate the Down syndrome risk. This measurement is very operator dependent and we go to great lengths to ensure the highest standards are achieved in producing an accurate measurement. We are accredited for nuchal translucency assessment with the Royal Australian and New Zealand College of Obstetricians and Gynaecologists / Fetal Medicine Foundation accreditation program. The thicker the nuchal translucency the higher the risk. The results of a blood test taken at 10-12 weeks may be combined with the ultrasound results to produce a combined risk.
   
   
3. At this time many physical structures of the fetus can be examined, for most women the information obtained can be maximized with a vaginal scan. All the abnormalities detectable at 18-20 weeks cannot be detected at this stage, therefore women wishing to have a thorough check of physical development should still consider a scan at 18-20 weeks. We can however maximize the detection of abnormalities by careful examination at this gestation.
   
   
4. Provision of results: We take it as our responsibility to communicate results in detail to all women having this service. This means showing women their individual risk on the day. Most women have a blood test as well as the ultrasound scan, they can get the combined results through us within ½ an hour of the scan or by ringing later in the same day. We go through the results carefully with each patient in an attempt to ensure that they understand the significance of the results.

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Why have a scan at 12-13 weeks?
It has been shown that a high proportion of fetuses with a chromosome abnormality such as Down syndrome can be suspected at an ultrasound examination at 12-13 weeks. All fetuses at 12-13 weeks retain small amounts of fluid under the skin around the head and neck, but this is usually slightly increased when Down syndrome is present. This is not an “abnormality” because the fluid is absorbed during the pregnancy – usually it is gone by 18-20 weeks. Additional fluid therefore does no harm but can be used as a marker for Down syndrome. Fluid under the skin looks black on ultrasound, and we measure the “nuchal translucency” or black area, when this are is thickened it is called “nuchal oedema” (or swelling behind the neck).

Pregnant women who wish to exclude chromosome abnormality can choose to have amniocentesis or CVS. What we can do however, using software developed by the Fetal Medicine Foundation in London, is tell pregnant women the risk that their fetus has a chromosome abnormality. This is calculated from their age, the thickness of the “nuchal translucency”, and the number of weeks pregnant they are (because the thickness varies with the number of weeks).

The benefits of a scan at this stage include:

• Highest detection rate of any “no risk” or screening test for chromosome abnormality (including Down syndrome)
• Accurate dating of the pregnancy
• Diagnosis of multiple pregnancy
• Diagnosis of early pregnancy failure (at 12 weeks approximately 1 in 50 women are found on ultrasound to have a failed pregnancy)
• Detection of many physical abnormalities is possible with ultrasound at this stage.

When should the scan be carried out?
The scan is performed between 12 and 13 weeks. If the pregnancy is found to be less advanced than expected then rescheduling may be required.

Will the scan be carried out through the abdomen or through the vagina?
For 9 out of 10 patients the measurements of the nuchal translucency can be carried out with a scan through the abdomen, so this will be the first part of the examination. If the measurement could be carried out better through the vagina then you would be offered this method (of course you are always free to refuse any examination you do not wish to have). Having finished the scan through the abdomen most women will be offered an additional scan through the vagina since this usually gives better images of the fetus, and therefore offers a better chance of detecting any physical abnormality. Physical abnormalities are usually best detected at 18-20 weeks, however many abnormalities can be detected at this early stage, particularly with a vaginal scan.

Serum Screening
Serum screening, which requires a simple blood test, may also be ordered by your doctor. The combination of a scan at 12-13 weeks plus a blood test improves the detection rate of Down Syndrome. The blood test is most informative if collected during the tenth week of pregnancy, however it can be collected up until 13 weeks of pregnancy. If you have had a blood test taken, after the scan the Victorian Clinical Genetics Service at the Royal Children’s Hospital will combine the ultrasound result with the serum screening and within one hour during normal working hours we can communicate the results to you. You are most welcome to wait to be told the results in person, although most people at low risk ring us for their results.

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Who will carry out the scan
One of the doctors will be involved in the examination, usually with the assistance of a sonographer (an ultrasound technologist). The results are assessed using soft-ware developed in London by Professor Nicolaides of the Fetal Medicine Foundation. Melbourne Ultrasound for Women are the Victorian Training Centre for the Foundation. We have continuous ongoing audit to ensure that all operators at Melbourne Ultrasound for Women continue to obtain reproducible measurements. At the end of the examination you will be told whether we consider the result to be high or low risk and these results will be sent to your doctor.

Can I discuss the results in detail with a staff member?
If your doctor has referred you to this practice for counselling as well as an ultrasound examination, you may see one of our counsellors to discuss not only the results but also options for further testing.

Scans at 14-17 weeks.
Reasons for scan: Ultrasound examinations are not often requested at this stage, but they may be performed in association with amniocentesis, when there are complications of pregnancy such as bleeding, or occasionally to review suspected problems seen in an earlier scan.

What can be seen? All of the structures visible at an 18-20 weeks scan can be seen, but because the fetus is smaller they are seen less well.

18-20 week (mid-trimester) scan
Reason for scan: Women are offered a scan at this stage primarily as a check for fetal development.

What can be seen?: The fetal structures are usually identified well at this examination. While this is an excellent time to examine the fetus and you are likely to be impressed with the quality of the images, it needs to be realized that not all abnormalities can be detected with ultrasound.

What is the best time, 18, 19 or 20 weeks? 19 –20 weeks is usually the best time for the examination, 18 weeks is satisfactory for slim women.

What will be seen: The fetus is systematically examined from the head to the feet. If you would like detailed information on what is looked for, this can be seen at the Australasian Society of Ultrasound in Medicine website at http://www.asum.com.au

Scans from 21 weeks until delivery
Reasons for scan: The commonest reasons are for checking the growth and wellbeing of the fetus.

What can be seen?: The same structures seen at the 18-20 week scan can still be seen with advancing pregnancy but it is often more difficult. This is due both to the increasing size of the fetus and the fact that there is relatively less amniotic fluid present later in pregnancy. You will also find it much more difficult to see “ baby like” pictures since ultrasound images are commonly poorer quality later in pregnancy.

While ultrasound cannot precisely estimate weight, by combing the abdominal circumference of the fetus with other measurements a weight estimate is obtained. To check the well being of the fetus we look at a range of tests, these include tests of amniotic fluid volume, tests of activity, breathing and tone of the fetus. We can also check blood flow through the umbilical cord and elsewhere in the fetus.

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What about 3D/4D Ultrasound?
3D and 4D (moving 3D images) are available at our practice on request. While beautiful easily recognizable images can sometimes be obtained with 3D and 4 D, it should be remembered that:

• Diagnosis of an abnormality is made primarily with 2D only– 3D is used for occasional abnormalities but usually only after they have been first seen with 2D.
• 3D images vary greatly with the fetal position, number of weeks and other factors. It is not always possible to obtain pleasing 3D pictures.

Amniocentesis and Chorionic villus sampling (CVS)
In these tests a needle is passed into the amniotic fluid or the placenta respectively to take the material to assess the fetal chromosomes or to perform other fetal tests.

Who is offered Amniocentesis or CVS
Women of 37 years and over at the estimated time of delivery are routinely offered testing in Victoria. Some younger women may also be offered it (in many other states of Australia and other countries it is offered at 35 years or even younger).

Other reasons for offering an amniocentesis include:

• Women who have already had a child with a chromosomal abnormalitysuch as Down Syndrome
• Women who know that an inherited disorder runs in their faimly or in the family of their partner
• Women who have a screening tests showing increased risk - a blood test and/or early ultrasound scan for determining who is at increased risk of a fetus with a condition such as Down Syndrome
• Occasionally amniocentesis is performed for other reasons. These include couples who are known to have a chromosome abnormality themselves, plus those known to be at risk of having a baby with one of a number of other rare disorders.

Why are older women offered Amniocentesis or CVS:
As a woman's age increases, her chance of having a baby with a chromosomal abnormality , such as Down Sydrome is the same whether or not this is the first child.

With increased age there is no increase in the chance of having a baby with spina bifida. Most other abnormalities also do not depend on the age of the pregnant women, so that if the chromosomes are normal then most of the increased risk an "older" women has of delivering a baby with an abnormality is removed.

It is important when looking at the chance of a baby having a chromosome abnormality is to keep the figures in perspective:

• approximately 4% of babies have some abnormality at birth and most of these have normal chromosomes.
• Chromosome abnormalities are rare compared to many of the other risks of pregnancy, for example 5% of babies are born early.

What types of disorders are detected?
The abnormalities looked for include:

• Chromosome abnormalities such as Down syndrome
• Neural tube defects (ie. spina bifida or ancencephaly)
• Some inherited disorders in those couples who have been shown to be at high risk, eg cystic fibrosis

Amniocentesis is not a general test for the fetus - it tests for only very particular problems, usually only chromosomal abnormalities and spina bifida.

CVS
What is CVS?
CVS (Chorionic Villus Sampling) involves passing a needle into the developing placenta (at this stage the placenta is called the ‘chorion’) and drawing a few small fragments of tissue up into a syringe. The placenta has the same genetic makeup as the fetus.

What type of disorders can be detected by CVS?

• Chromosome abnormalities such as Down Syndrome
• Some inherited disorders when couples are known to be at high risk
• CVS is not a general test for the fetus - it tests only for very particular problems, usually only chromosomal abnormalities.

When is CVS carried out?
CVS may be performed anytime from 10 weeks onwards.

Why is an ultrasound scan needed before CVS?
An ultrasound scan is carried out to confirm the age of the pregnancy, to make sure there are not twins and to check that the pregnancy appears healthy. The fetus is still small so very few physical abnormalities can be detected at this stage. It is also too early to assess Down Syndrome risk using ultrasound, although if there is increased fluid in the skin around the head and neck, then there is an increased chance of Down Syndrome.

What should I do before the test?
A full bladder is not required. On the day of the test you should expect to be at our practice for one and a half hours.

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What happens on the day of the test?
The test is usually well tolerated and many women do not use pain relief. Nitrous oxide gas, the gas used in labour, is available for the procedure if you wish to have it. This helps to keep you comfortable during the test, but does not put you to sleep. Local anaesthetic is also available.

The sample is taken using a needle passed through the abdomen – called transabdominal CVS. A fine needle is passed through the skin and into the uterus to the edge of the placenta. The path of the needle is followed carefully on the ultrasound screen. A finer needle is then passed through the outer needle into the placental tissue. A syringe is used to draw up very small fragments of placental tissue. The tissue is examined to make sure it is adequate. If required, further aspirations are performed through the inner needle without any additional discomfort. The needle at no time is passed into the amniotic sac - this helps minimise the risk of the test, and any movement of the fetus during the test causes no concern. It usually takes only 1-2 minutes to perform the test. At the end of the procedure the fetus is checked and you are able to leave the room immediately. After waiting for about 30 minutes you are then able to go home. The amount of discomfort with CVS varies, but it is usually well tolerated.

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What is done with the cells?
The cells obtained at CVS are allowed to grow in the laboratory until there are enough for testing the chromosomes. Each of the chromosomes is carefully examined to check that there are the correct number and that the appearance and length of each chromosome is normal. If the fetus has Down Syndrome then there is an additional chromosome 21 present. The sex of the fetus can also be determined by looking at the chromosomes - you can find this out if you ask your doctor.

Results
The laboratory will usually have the result availble within 2 weeks. Your doctor will be informed and he or she will pass it on to you.

DNA DIAGNOSIS
Testing with FISH
There is a very quick way to test cells for some chromosome abnormalities. It is a DNA test called FISH(Fluorescent In Situ Hybrization). The laboratory charges extra for FISH. Using this technique some of the chromosomes can be tested in 24-48 hours following the procedure. The most common FISH test excludes about 90% of chromosome abnormalities that are significant to live born children by testing chromosome 21, (Down Syndrome), plus 13 and 18 and the sex chromosomes.

DNA diagnosis is sometimes available for couples at special risk of other abnormalities, especially for diseases caused by gene defects, such as cystic fibrosis and fragile X. Many other disorders can also be tested (the number increases each year). These conditions are not tested unless there is a special indication, each test is expensive.

How will I feel afterwards?
Most people appreciate having a companion to drive them home after a CVS. It is recommended that you rest for the remainder of the day, although there is no reason to go bed. There need be no further limitation of routine after this time. If you have a long trip home, it is preferred that you stay in Melbourne overnight after the procedure.

After the CVS some women feel lower abdominal discomfort or period like pains and some may feel faint for a short time. These symptoms are not associated with any risk to the pregnancy. It is very uncommon to have any bleeding after transabdominal CVS.

What are the risks of the test?
A study which included Lachlan de Crespigny’s patients suggested that the risk of miscarriage from CVS itself is 1 in 100 or less. (There is also the natural miscarriage rate which is approximately 1 in 50 after 10 weeks whether or not you have a CVS).

Patients often ask when a miscarriage might occur after CVS. Because most miscarriages after CVS are “natural” miscarriages which are unrelated to the test this is a difficult question to answer. If however there has been no problem by three weeks after the test then any complications would be unlikely to be due to the test. The chance of complications is very much related to the experience and expertise of the operator. All doctors in our practice are very experienced at CVS and carry out large numbers of procedures. There is no evidence of CVS causing limb or other fetal defects at the time we offer the test, ie. at 10 weeks or more. Rare complications include bleeding, infection and ruptured membranes. Complications to the pregnant woman herself are extremely rare. If your blood group is Rh negative you should have anti-D after the CVS, although if your doctor has indicated that you have antibodies then amniocentesis is preferable.

CVS like any test may fail because an inadequate sample is obtained or because the laboratory cannot produce a result. Both of these risks are very uncommon. Incorrect results are possible but are extremely rare. In approximately 1% of patients uncertain results occur which may need a further test (usually amniocentesis) to sort them out.

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What should I look for after the test?
If there is any blood or clear fluid from the vagina, you should consult your own doctor.

What does a test cost?
Details of charges are available from our practice. We will give you an account for the test itself plus the laboratory will separately send an account for analysis of the specimen. Medicare will cover part of the cost for each of these accounts.

What if the results show an abnormality is present?
Those few patients in whom the test shows that the fetus has an abnormality will be given information so that they can make a choice about whether to continue the pregnancy. Counselling is available. If a couple decide to terminate the pregnancy, because of an abnormality detected at CVS, the procedure is usually a straightforward ‘D & C’ (i.e ‘curette’) in hospital.

What alternative methods are available to test the chromosomes?
The chromosomes may also be tested by amniocentesis - a pamphlet is available for this test. CVS can also be carried out via the transcervical approach. In our hands, a transabdominal approach is safer. CVS cannot test for spina bifida. Unlike Down Syndrome, spina bifida is not more common in pregnancies of “older” women. An ultrasound examination at 18 to 20 weeks can detect many physical abnormalities of the fetus, including spina bifida.

Amniocentesis
What is amniocentesis?
An amniocentesis involves taking a small sample of amniotic fluid (water) from around the developing fetus. A needle is first passed through the pregnant woman’ s skin, then through the wall of the uterus (womb), and on into the amniotic fluid. Approximately 15 mls (3 teaspoonsful) of fluid is taken, this amount being small compared with the total amount of fluid present at the time of the test at 15 weeks.

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Who is offered amniocentesis or CVS?
Women of 37 years and over at the estimated time of delivery are routinely offered testing in Victoria. Some younger women may also be offered it (in many other states of Australia and other countries it is offered at 35 years or even younger). Other reasons for offering an amniocentesis include:

• Women who have already had a child with a chromosomal problem such as Down Syndrome,
• Women who know that an inherited disorder runs in their family or in the family of their partner,
• Women who have a screening test showing increased risk – a blood test and/or early ultrasound scan for determining who is at increased risk of a fetus with a condition such as Down Syndrome
• Occasionally amniocentesis is performed for other reasons. These include couples who are known to have a chromosome abnormality themselves, plus those known to be at risk of having a baby with one of a number of other rare disorders.
• Women of any age may choose to have a test – it provides certainty about the chromosomes and is an option for any informed woman.

Why are older women offered amniocentesis or CVS?
The chance of Down Syndrome is the same whether or not this is the first child. As a woman’s age increases, her chance of having a baby with a chromosome abnormality, such as Down Syndrome, also increases. Most other abnormalities do not depend on the age of the pregnant woman, so that if the chromosomes are normal then most of the increased risk an ‘older’ pregnant woman has of delivering a baby with an abnormality is removed. It is important when looking at the chance of a baby having a chromosome abnormality is to keep the figures in perspective:

• approximately 4% of babies have some abnormality at birth and most of these have normal chromosomes.
• chromosome abnormalities are rare compared to many of the other risks of pregnancy, for example 5% of babies are born early.

What types of disorders can be detected by amniocentesis?
The abnormalities looked for include:

• Chromosome abnormalities such as Down syndrome,
• Neural tube defects (ie. spina bifida or anencephaly),although ultrasound rather than amniocentesis is the usual test for neural tube defects.
• Some inherited disorders in those couples who have been shown to be at high risk, eg. cystic fibrosis

When is amniocentesis carried out?
The earliest we carry out amniocentesis is 15 weeks. It is safer to wait until this time - ‘early amniocentesis’ prior to 15 weeks has a higher risk of miscarriage.

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Why is an ultrasound examination needed before the amniocentesis?
An ultrasound examination will first be carried out to confirm the age of the pregnancy, to make sure there are not twins, and to check for physical abnormalities of the fetus.

By locating the position of the fetus and placenta, steps can be taken to avoid them during the amniocentesis. Ultrasound is used throughout the amniocentesis procedure to first guide the needle to the safest position, and then to keep the needle away from the fetus.

Your doctor may arrange for another scan at around 19 to 20 weeks when a more detailed check is usually possible.

What should I do before the Test?
It is not necessary to have a full bladder, however having some urine in the bladder may make it easier to examine the fetus and lower part of the uterus.

You should expect to be at our practice for approximately 1 1/2 hours.

What happens on the day of the test?
When the scan has been completed the amniocentesis is performed without you having to move from the examination couch. After cleaning the skin, a very fine needle is inserted into the uterus watching the needle all the time on the ultrasound screen. It then only takes about 30 seconds to draw the required 15 mls (3 teaspoons) of fluid into the syringe. The needle is removed and the fetus is again checked. After waiting for about 20 minutes you are then able to return home. Patients usually feel far less discomfort from the test than they expected - many indicate that it is not even as bad as a simple blood test. If you are worried about the test nitrous oxide, the gas used in labour, is available, although most patients find they do not need it.

What is done with the cells?
Amniotic fluid contains cells which have been shed by the fetus. They are allowed to grow in the laboratory until there are enough to test the chromosomes. Each of the chromosomes from a number of cells is carefully examined to check that the correct number are present and that the appearance and length of each chromosome is normal. If the fetus has Down Syndrome then there is an additional chromosome 21 present. The sex can also be determined by looking at the chromosomes - you can find this out if you ask your doctor.

RESULTS: Including the option of FISH
The laboratory will usually have the chromosome result available within 2 weeks - your doctor will be informed and he or she will pass it onto you.

If you wish, an extra test, called FISH, can be carried out to tell you within 2 working days if Down Syndrome is present. The laboratory charges extra for FISH.

Testing with FISH
There is a second very quick way to test the specimen for some chromosome abnormalities. There is a DNA test called FISH (Flourescent In Situ Hybridization). Using this technique some of the chromosomes can be tested by 24 – 48 hours after the test. The most common FISH test excludes about 90% of chromosome abnormalities that are significant to live born children by testing chromosomes 21, looking for Down syndrome, plus 13 and 18 and the sex chromosomes. FISH is also used for couples at special risk of other abnormalities, especially for diseases caused by gene defects. These include cystic fibrosis, and fragile X. Many other disorders can also be tested - the number increases each year. However each disease tested is expensive – except for the 5 major chromosome abnormalities FISH is not used unless there is a special indication.

It is important to realize that FISH tests only for a narrow group of very specific chromosome abnormalities. The traditional culture method described above is always done as well as FISH since this allows each of the chromosomes to be analysed.

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How will I feel afterwards?
While you will be quite capable of driving yourself home after the test, most people appreciate having a companion to drive home. It is recommended that you rest for the remainder of the day although there is no reason for you to go to bed. There need be no further limitation on your normal routine after this time. If you have a long trip home, it is preferred that you stay in Melbourne overnight afterwards. Occasionally after the test patients may have either mild discomfort or some bruising under the skin but neither causes any problem to the pregnancy.

What complications can occur?
In a study Lachlan de Crespigny carried out, including his and one other doctor’s results, the miscarriage result was not demonstrably higher than those who did not have the test performed. The risk of the test causing miscarriage therefore is very low, a best estimate is 1 in 200 or less. There is also about a 1 in 100 chance of having some leakage of amniotic fluid through the vagina after the procedure. This usually stops if you rest and it can be expected to cause no problem to the fetus or the pregnancy. If your blood group is Rh negative, anti-D is usually given. Direct injury to the fetus by the needle has not been reported after any of our patients. Rarely have any complications to the pregnant woman or other complications to the fetus been reported.

Couples often ask when a miscarriage would occur. This is a difficult question because at least two out of three miscarriages after amniocentesis are totally unrelated to the test itself and would have occurred anyway. However, if you have had no problem by three weeks then any complication is unlikely to be due to the test. The chance of complications is very much related to the experience and expertise of the operator. The test, like any other, may fail either because no specimen is obtained or because the laboratory are unable to grow the cells. Both of these are very uncommon. Incorrect results are extremely rare. Rarely uncertain results may occur - these may need a further test such as a sample of fetal blood to sort them out.

What should I look for after the test?
If you lose blood or clear fluid from the vagina after the test then you should contact your own doctor.

What if the amniocentesis shows that an abnormality is present?
Those few patients in whom the tests show that the fetus has an abnormality will be given information so that they can make a choice about whether to continue the pregnancy. It is still possible to perform a termination of the pregnancy at this stage. Counselling is available to help couples make their decision.

Should I have an ultrasound examination later in the pregnancy?
This depends on how well the fetus can be seen at the time of the amniocentesis. Usually some details of the structure are difficult to see at this early stage. Further scans need to be discussed with your doctor, but most patients choose to have a further scan at around 20 weeks.

What does the test cost?
Details of charges are available at our practice. Please note that the laboratory will send a separate account for the analysis of the specimen plus any necessary blood tests. Medicare will cover part of the cost of these accounts.

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Summary
In experienced hands, amniocentesis is a straight forward procedure which is well tolerated by patients and complications are rare. It is usually performed in patients with special indications, the commonest being the age of the pregnant woman. The test checks for Down Syndrome and other chromosome abnormalities, and also for spina bifida. It is important to realise that while the combination of an ultrasound scan and amniocentesis goes a long way to ensuring that the fetus is normal, it does not guarantee that every possible abnormality has been excluded. If you would like more information, please ask. If you would like more written information we have pamphlets available on ultrasound and other procedures. For more detailed information, you may purchase a book Lachlan has written, “Which Tests For My Unborn Baby? A Guide to Prenatal Diagnosis” (OUP) which is available at a reduced price at our practice.

What do we need to know before carrying out a CVS or Amniocentesis?
There is a request form for testing that our counsellor will go through with you prior to the procedure. In particular please note

1. If you carry an infectious disease such as hepatitis C, we would recommend an amniocentesis rather than CVS.
2. We need to know your blood group before your test.
3. We will ask you whether you wish to have a FISH test. This is explained under the CVS and amniocentesis sections. It provides a partial result within 2 working days for an additional cost.

Other information is available through our rooms:

1. VCGS combined test pamphlet.
2. Choroid Plexus Cysts
3. Pylectasis
4. Low Lying Placenta
5. Gynaecological Ultrasound
6. Endometrial thickness
7. Saline infusion sonohysterography
8. Levovist

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