存在孤立脉络膜丛囊肿(cpc)在中期妊娠 ultrasound 焦虑是一种常见的原因，尽管它几乎总是无辜的 finding. Here are the answers to some commonly asked questions about CPCs.
What are choroid plexus cysts?
脉络膜丛是大脑中产生脑脊液的部分, 脑脊液通常用来保护大脑和脊柱的液体. 在大约1%到2%的正常婴儿中——50到100个婴儿中有1个——当脉络膜丛形成时，一个微小的液体泡会被挤压掉. 超声显示为脉络膜丛内的囊肿. 脉络膜丛囊肿可比作水疱，不被认为是脑异常.
What is going to happen to the cyst?
在绝大多数情况下，囊肿消退或消失，没有任何后果.
如前所述，脉络膜丛囊肿存在于1%至2%的正常胎儿中. However, 有脉络膜丛囊肿的胎儿比例很小, 有一种相关的染色体疾病叫做18三体. 18三体胎儿有一个额外的18号染色体拷贝. Frequently, fetuses with trisomy 18 are stillborn. Survivors beyond infancy are rare. 他们有严重的智力障碍和各种其他问题, 包括几乎任何器官系统的异常(如心脏), brain or kidneys). 18三体胎儿约三分之一有脉络丛囊肿. 因此，当我们看到脉络膜丛囊肿时，我们担心胎儿可能患有18三体.
Trisomy 18 is rare. It is present in less than 1 in 3,000 newborns. 脉络膜丛囊肿在正常胎儿中比较常见. Most fetuses with a choroid plexus cyst are normal. Furthermore, 许多与18三体相关的异常可以通过仔细的超声波检测到. In fact, 除了脉络膜丛囊肿外，18三体胎儿几乎总是在超声上表现出异常, although some of these abnormalities can be quite subtle. 如果通过彻底的“II级”超声检查未发现其他异常, the likelihood the fetus has trisomy 18 is very low.
What are the odds that it is a sign of trisomy 18?
确切的风险率很难估计，而且有些争议, but most doctors believe it is well under 1 percent. In other words, 如果胎儿患有脉络膜丛囊肿，但超声检查结果正常，那么他不患18型三体的几率超过99%. 正常的甲胎蛋白(AFP)检测进一步降低了18三体的可能性.
Does the size of the cyst matter?
通常情况下，囊肿的大小无关紧要，但多发、大的囊肿会让人更担心.
What is the next step after a cyst is discovered?
We can perform an amniocentesis, 数一数胎儿的染色体数目以确定没有多余的18号染色体. At the same time, we can rule out other chromosomal abnormalities, such as Down syndrome, 虽然我们没有理由怀疑你的案子有这些. 然而，羊膜穿刺术导致流产的风险很小.
How high is the miscarriage risk with amniocentesis?
羊膜穿刺术流产的风险很难确定. Many doctors cite 0.5 percent or 1 in 200.
Can I just wait to see if the cyst resolves?
That won't help your decision, because cysts almost always resolve in both normal fetuses, as well at those with trisomy 18. The natural course for a CPC is to resolve or disappear. 然而，即使囊肿消退，也不能降低胎儿患18三体的几率.
如果你什么都不做，你应该确信你的孩子很可能有正常的染色体. If you have not yet had an alpha fetoprotein (AFP) test, 这可以进一步评估患18三体的几率. A level II ultrasound, or a targeted scan, should be done, 如果还没有找到18三体的其他迹象.
If you need to be certain, we can do the amniocentesis, 因为知道这是不太可能导致并发症的. 你的决定应该取决于你如何处理羊膜穿刺术的信息, how you would feel about a miscarriage, 你会如何看待一个受影响的孩子，以及在孩子出生之前你可能会感受到的焦虑. If you want to proceed with the amniocentesis, 你可以放心，手术的并发症是非常罕见的.
加州大学旧金山分校健康医学专家已经审查了这些信息. 它仅用于教育目的，并不打算取代您的十大赌博平台排行榜或其他医疗保健提供者的建议. 我们鼓励您与您的供应商讨论您可能遇到的任何问题或疑虑.
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