In recent years, several new tests have become available primarily aimed at testing for Down syndrome. These tests are optional tests in addition to the usual blood and detailed ultrasound examination at 18 to 20 weeks. This information sheet provides a summary of the tests available and is intended to be a reminder of the issues that we discussed today.
What is Down Syndrome?
Down syndrome (Trisomy 21) is a condition in which an extra chromosome 21 is carried in each of the cells of the body. The extra chromosome 21 results in intellectual disability of varying degrees and may cause problems with the heart, kidneys, bowel, eyesight or hearing. Although the chance of having a baby with the Down syndrome increases with mother’s age, Down syndrome babies may also be born to younger mothers. The following table indicates the risk of having a baby born with Down syndrome.
Maternal Age at the expected time of delivery Approximate risk of baby being born with Down’s Syndrome
25 1 in 1250
30 1 in 890
35 1 in 355
37 1 in 220
40 1 in 90
45 1 in 23
What is Edward Syndrome?
Edward syndrome (Trisomy 18) is a very serious condition in which an extra chromosome 18 is carried in each of the cells of the body. This condition occurs much less often than Down syndrome. Most pregnancies affected by Edward syndrome will miscarry. Those that continue may have a baby affected with heart, kidney or lung problems. Many other features may be apparent on ultrasound examination.
What are neural tube defects?
The most common neural tube defects are spina bifida and anencephaly. Babies with spina bifida have an opening in the bones of the spine which may result in damage to the nerves controlling the lower part of the body. This can cause weakness and paralysis of the legs and sometimes inability to control the bowel and the bladder. In anencephaly, the brain does not develop properly and the baby will not survive. Around 1:750 pregnancies are affected by a neural tube defect if the mother has not been taking folate around the time of conception. This risk is dramatically reduced, although not eliminated, by taking folate.
How reliable are these tests?
The reliability of a test depends on its ability to detect a problem if it is there: the sensitivity of the test. Sensitivity of 80% means that a test will detect 80% of babies who have the problem (miss 20%). The other important factor in assessing the reliability of the test is the false positive rate. A test is considered to give a false positive result if it suggests there is a problem but the subsequently shown not to be there at all. Ideally a test would have 100% sensitivity and 0% false positive rate but in practice this does not happen.
Low risk means that the risk of having a baby with Down syndrome, Edward syndrome or a neural tube defect is low. Increased risk means that there is an above average risk of having a baby with one of these conditions but it does not necessarily mean that there is a problem with your unborn baby. It means that further tests should be considered to determine if there is a problem. It is important to remember that most women with an increased risk will go on to have a normal baby.
OPTIONS FOR PRENATAL TESTING
1. No testing.
With the risk of these conditions being very low, it may well be your preference not to have any testing at all. This is a completely appropriate decision that is entirely yours to make.
2. Nuchal translucency (NT) scan
Between 11-14 weeks all babies have a small amount of fluid under the skin at the back of the neck. An excessive amount of fluid in this area is associated with a higher chance of having a baby with Down syndrome or other abnormalities such as heart or kidney problems. This can be measured by ultrasound and is called nuchal translucency. If there is an excessive amount of fluid then further investigations will be recommended. An ultrasound at this stage also has additional benefits such as accurate dating the pregnancy, diagnosis of multiple pregnancies and other unrelated abnormalities.
3. Combined first trimester test
The combined first trimester test for Down syndrome involves combining the results of the nuchal translucency scan with the results of a blood test performed at least 2 to 4 days prior to the ultrasound.
4. Maternal serum screening (MSS)
Maternal serum screening is a blood test between 14-20 week for pregnant women to determine if they may be at risk of having a baby with Down syndrome, Edward syndrome or a neural tube defect.
5. Chorionic villus sampling (CVS)
Chorionic villus sampling involves passing a needle into the placenta between 10 and 13 weeks gestation. A small amount of placental tissue is taken for chromosome analysis. Results take approximately seven working days to become available. Some ultrasound centres will offer you the option of FISH testing. This is a very rapid test for Down syndrome with the result being available the following day at an additional cost. Further details of the actual procedure will be given to you if this is the option you choose. The risk of miscarriage from the procedure itself is 0.5-1.0%. You must remember that there is a risk of spontaneous miscarriage at this gestation of approximately 2%. The total risk is therefore 2.5-3.0% although only a small proportion of this risk of miscarriage is actually as a result of the CVS test.
6. Amniocentesis
Amniocentesis involves taking a sample of amniotic fluid from around the developing baby at approximately 16 weeks gestation. Only a small amount of fluid is taken but this is enough for a full chromosome analysis to be performed. Results take approximately seven working days to become available. Some ultrasound centres will offer you the option of FISH testing. This is a very rapid test for Down syndrome with the result being available the following day at an additional cost. The risk of miscarriage from the procedure itself is approximately 0.5%. The risk of spontaneous miscarriage at this gestation is 0.5%. The total risk from the procedure and spontaneous miscarriage is 1.0%.
Summary
You should not feel pressured to undertake any of these tests if you do not wish to do so. It is important to recognise that the choice of testing is yours. I will give you advice on the different types of tests available but the ultimate decision must rest with you. The following table summaries the sensitivity, false positive rates and risk of each test for Down's syndrome
Test | Weeks of test | Detection rate | False positive rate | Risk of miscarriage from the test |
No test | 0% | 0% | 0% | |
NT | 11-14 | 80% | 5% | 0% |
Combined 1st trimester test | 11-14 | 90% | 5% | 0% |
2nd trimester MSS | 14-20 | 80% | 5% | 0% |
CVS | 10-13 | 100% | 0% | 0.5-1% 评论 谢谢LZ分享!等我明天有空帮LZ翻译一下,就方便很多英文不好的姐妹们。 评论 呀,花生还没有翻译捏?都好多个明天了捏。。。 评论 还没有翻译吗? 评论 自己上中文网站上看看就行了。。 别浪费别人的时间翻译了。。 评论 GP那里有中文版的,不用翻译啦,反正按年龄看看概率多少就行。 澳洲中文论坛热点
幼儿产妇 想向大家推荐一个网课,豌豆思维,大家有参加过么澳大利亚小朋友豌豆思维课的感受: 首先他喜欢动画,这点是最吸引我儿子的地方,里面有好多的小故事都是动画里面的人物,然后穿插着老师边教边玩,本来我儿子是坐不住的,可是这个课程 ... 幼儿园规定如果孩子发烧,就必须被接回去,并且第二天也不能上幼儿园,有这样的明文规定澳大利亚幼儿园规定如果孩子发烧,就必须被接回去,并且第二天也不能上幼儿园,有这样的明文规定吗? 评论 必須接回去是真的,第二天不能上幼兒園就沒聽說過。 评论 哦,那如果第二天没 ... 小孩在幼儿园被其他家长打了澳大利亚今天小孩在幼儿园被其他家长打了,小孩3岁,好像是在和别的小朋友推搡,另外一个小朋友家长看到后直接过来打了我的小孩腿。回家路上小孩一直说被别人打了,喊疼,我说去医院她 ... 手足口病嘴巴要疼几天?澳大利亚2岁10个月的娃,今天第五天了,嘴巴疼的厉害,里面十来个破口,啥都吃不了,全靠喝牛奶续命。每天夜里哭醒十几次喊嘴巴疼。除了不发烧了以外一点好转迹象都没有,甚至我感觉嘴 ... 5分加分贴,办理澳洲护照是否需要去办理公民证澳大利亚父母都是pr,小孩这里出生,办理澳洲护照还需要花几百去办理那个公民证citizenship certificate吗,出生证难道不够? https://www.passports.gov.au/Citizenship Processing time,这种情况属于下面21天能下 ... 10个半月男宝身高不足70澳大利亚如题,出生身高不到10%曲线,4个月大时追上来点,到6个月又回到不到10%,感觉4到6个月没有长太快,现在基本就是每月长1厘米,有点焦虑。全奶粉,奶量从小就是奶瓶上月龄的最低奶量 ... 7岁小孩圣诞节回北京需要打什么疫苗吗澳大利亚7岁小孩,这个圣诞节假期打算带她回北京6周。 上次是春天回去的,这次因为是冬天,所以有些担心她生病,请问需要在澳洲提打什么疫苗吗? 去问了GP, GP也不知道,GOOGLE给我一篇文章 ... 有人办过寄养签证吗?澳大利亚听说寄养签证可以办中国的居留许可,还可以回国入读公立小学,出入中国免签,想呆多久呆多久,有点心动。我姐一家在深圳,如果名义上把孩子寄养到她那里(当然回国的时候家长 ... 想看私人Ob,又想回国生澳大利亚想第六周去看私人OB,但是看网上说有management fee好几千? 但是我想着最后回国生,比如20几周回国。 这样的话在这看Ob还是要付好几千的management fee 吗 评论 除非极有钱,不然回国生产 ... 7岁孩子买什么样的汽车座椅澳大利亚孩子还有1个月就7岁了,现在没到1米三。有辆备用车,不知道是否应该给孩子买汽车座椅。 是不是7岁就不用坐汽车座椅了?还是需要买了垫子? 有没有推荐的? 评论 身高不够就用bo ... 墨尔本试管IVF心态崩溃澳大利亚心态崩了,上论坛发泄一下 楼主坐标墨尔本,内异四期,去年手术以后备孕也没成功,还出现了粘连和腺肌症,老公那边没问题,今年年初开始做试管。 做之前参考了坛里姐妹的经历, ... 一楼有链接@@@200首经典的nursery Rhymes❤低龄儿童必备❤请砸分分分分。。。澳大利亚Itunes里面$1.69一首的,我这有全部200首 下载请加分 https://onedrive.live.com/redir?resid=78D7C67142EAEF62%21149 评论 压缩后附件135M哦 评论 谢谢,能给我发一个吗 评论 [email protected]谢谢楼主 评论 jie ... 奶爸带两个小仔白天飞机回国需要注意什么?澳大利亚首都航空特价三个人回国往返才1100刀,果断订票回国玩两周,杭州转机,提供住宿一晚 俩儿子一个2岁一个5岁,打算hiking baby carrier背着老二,老大自己拖着自己的Stokke箱子跟着走没问题 ... 男孩子夏天穿什么裤子澳大利亚最近有个问题困扰我,不知道给快三岁的儿子买什么裤子穿。姐姐小时候到了现在的季节可以穿leggings,薄薄的很凉快,也可以保护摔倒时不至于擦破腿。但是我观察童装店里男孩子穿的 ... 持分请教:辨别颜色澳大利亚宝贝三岁,可以准确的辨别红色,绿色,黄色,黑色。但是每次指着蓝色的时候,他就说是黄色。 想问一下,这是蓝色色盲吗?还是只是因为小朋友淘气,或者因为发蓝色发音困难,所 ... 关于产后康复澳大利亚生老大的时候非常简单女儿size小也年轻,很容易就恢复很好,还有家长一直帮忙照顾,虽然五六十天还感觉有点虚,但没其他的症状,多了百日就一切如初了。 老二近8斤,可能也和年 ... 小女孩长青春痘,用啥药澳大利亚还有几年到teens, 但是小姑娘已经开始有黑头和小红疙瘩了。 对战痘很有丰富经验的我,20多年了 见过的痘太多了 我给她用了我的痘痘药Benzac 2.5% 她觉得很疼,小女孩皮肤肯定很嫩。 这 ... 请推荐speech therapist 给2岁半男孩澳大利亚2岁半男孩,因为之前听力受损导致language delay,后来通过耳管手术听力有恢复。 但是语言发育非常落后,目前还不能说两个单词以上的句子,只能说一些简单单词比如apple, banana, berry, ... |