If you have just received a prenatal diagnosis of Trisomy 18, I'm sure many questions are going through your mind. What is the cause of Trisomy 18 (Edwards syndrome)? What does this mean for my baby? Is there any treatment? What would it be like carrying to term? What will my baby look like? Where can I find stories and pictures of babies with Trisomy 18? Where can I find support from other parents who are raising a child with Edwards Syndrome?
We had the same questions when our daughter Abigail was diagnosed with Trisomy 18. You can see how we found the answers to these questions in Abigail's Story and Pictures and we would like to share with you what we have learned.
What is Trisomy 18? What causes it? Trisomy 18 occurs when a baby has three chromosomes in the eighteenth position instead of the normal two. It is also called Edwards syndrome (or Edward's syndrome), and is the second most common trisomy, after Trisomy 21 (Down syndrome). It occurs in about 1:5000 to 1:8000 births.
The other type of trisomy is Trisomy 13 (Patau's Syndrome), which occurs less frequently than Edwards Syndrome. These three trisomies: 21, 18, and 13, are the only full trisomies that have ever led to a live birth. Most trisomies (about 95%) are full trisomies. That is, the extra chromosome occurs in every cell in the baby's body. This type of trisomy is not hereditary, and it is by far the most common type. In most literature, and on this website, Trisomy 18 means full Trisomy 18.
There are also partial and mosaic trisomies. Mosaic trisomies occur when the extra chromosome is present in some (not all) of the cells, and partial trisomies occur when only part of an extra chromosome is present. Some partial trisomies are translocations, usually caused by a parent's translocation, which may be hereditary. For more information, see Translocations from the The Centre for Genetics Education.
Unlike Down syndrome, Edwards Syndrome is usually fatal, with most of the babies dying before birth and those who do make it to birth typically living only a few days. However, a small number of babies (<10%) live at least one year (ref 1). To learn about Trisomy 18, we met with physicians, specialists, and genetic counselors and we searched the Internet and read as much as we could.
What we learned was that for Trisomy 18 babies, it is as if they don't quite get finished developing. For example, their brains are not properly developed; certain neurons don't make it all the way to the outside of the brain but remain in little clusters throughout the brain. This means that they will frequently have problems doing basic, instinctive, functions like sucking, swallowing, and breathing. And it is impossible to know the extent of these problems until the baby is born.
Some other typical problems are holes in the heart that don't close, openings in the back (spina bifida) and stomach (omphalocele), and organs that are not properly formed. Additionally, Trisomy 18 babies are usually small, as if they stopped developing and growing about the 7th month in utero.
One other key thing we learned was that Trisomy 18 babies have a susceptibility that healthy babies don't. That is, they succumb to things that would not be fatal to a healthy baby. Therefore, the approach of fixing the individual problems is rarely successful with babies with Trisomy 18. After learning these things, we explained Trisomy 18 very simply to others in A Letter to Our Friends that we gave them at our daughter's memorial service.
How is Trisomy 18 diagnosed? Sometimes a mother's AFP or quad screen test comes back as high risk for Trisomy 18 (ref 2). It is important to note that this is not a diagnosis, but a risk. When an AFP test indicates a high risk for Trisomy 18, usually a Level 2 ultrasound (also called a targeted ultrasound) is scheduled. The level 2 ultrasound is usually performed by a perinatologist or someone else who specializes in high-risk pregnancies. They are specially trained to look for the markers of Trisomy 18. These markers, often called soft markers, are characteristics frequently seen on babies with Edwards Syndrome.
The targeted (level 2) ultrasound is performed to look for markers such as clenched hands, choroid plexus cysts, rocker bottom feet, and delayed growth. Choroid plexus cysts, for example, often occur in healthy babies, and in the absence of other markers usually do not indicate Trisomy 18 (ref 3,4,5). Typically these soft markers, along with other common problems associated with Edwards Syndrome: heart defects such as VSD, ASD, and coarctation, kidney abnormalities, omphalocele, esophageal atresia, and polyhydramnios (excess amniotic fluid), can be identified via ultrasound prenatally. Studies have shown that most (but not all) babies with Trisomy 18 show some abnormalities during ultrasound (ref 6,7), although level 2 ultrasound is more likely to find them because they are looking specifically for these things. For more explanation of these markers, see Trisomy 18 Facts.
And even if multiple markers are found in an ultrasound, this is still not a diagnosis of Edwards Syndrome. The only ways to know with nearly 100% certainty that your unborn baby has Trisomy 18 is to do an amniocentesis or CVS (chorionic villi sampling). If an AFP or quad screen result shows a risk of Trisomy 18 of greater than 1:100, level 2 ultrasound results are usually used to determine if the doctor will recommend an amnio. If an obvious problem is found on ultrasound, an amnio is typically recommended, and if only a single soft marker is found, the possibility of amnio is usually discussed with the parents since the risk of having Edwards syndrome must be weighed against the risk of the amnio itself (ref 8).
The amnio results typically take 10 days or more, but there is a FISH test that can give preliminary results in a few days. From the amnio, they do a karyotype of your baby's cells, which will clearly show the extra eighteenth chromosome if it is present, indicating Edwards syndrome (see a karyotype of Edward's Syndrome). For a good description of all of these and other prenatal testing options see Prenatal Genetic Testing from the Genetics and Public Policy Center.
At this time, if you have a definite diagnosis of Edwards Syndrome, you are typically presented with the option to terminate the pregnancy. However, that is not the only option you have. The first thing to do is slow down and learn about Trisomy 18 and all the options before you make a decision that you will have to live with for the rest of your life. We chose to carry our daughter to term, and you can read about all the options you have, the benefits of carrying to term, as well as some of the MYTHS of Trisomy 18 in the Carrying to Term Resources section of this site.
What symptoms will my baby with Edwards Syndrome have? How long will my baby live? There are many and varied symptoms of Trisomy 18. In addition to the ones identified via ultrasound, babies with Trisomy 18 often have micrognathia (small jaw), low-set ears, and a strawberry-shaped head. But this description does not do them justice. I have seen pictures of hundreds of babies with Trisomy 18 and most of them are just tiny little dolls - they are just beautiful! After birth, they often have a weak cry and trouble sucking, and many suffer from apnea.
There are many sites which list the symptoms of Edwards Syndrome from a medical standpoint: Medline Plus Trisomy 18 is one of them, Lucille Packard Children's Hospital Medical Genetics Trisomy 18 & 13 is another, as well as eMedicine Trisomy 18. In addition, Trisomy 18 Facts from SOFT, is written by Dr. John Carey, probably the premier expert on Trisomy 13 and 18 in the world. However, your baby is much more than a list of symptoms. The Trisomy 18 Support Foundation has a section called Reading about Trisomy 18 with lots of good information about Edwards Syndrome: cause, treatment options, likelihood of occurring again. The Developmental Disabilities Digest includes information about medical management of Trisomy 18, from infancy to adulthood (yes, a few children with Trisomy 18 do make it to adulthood!).
It is very difficult to predict exactly what problems your baby will have because of Trisomy 18. Even though problems may be identified during ultrasound, there is really no way to know how long your baby's life will be. Many babies with very severe heart defects make it to live birth and live for weeks while many with no obvious abnormalities on ultrasound die in the womb. Your doctor does not know which group your baby will fall into by looking at an ultrasound. And after birth, it is also hard to tell which ones will live longer. But there are some kids with Trisomy 18 that have surprised their doctors and lived many years. That is one thing that makes it so hard to determine how to care for your baby.
Where can I find stories of babies with Edwards Syndrome? Reading about others' experiences will help you better understand more of the possibilities for your child. You can find stories of babies with Edwards Syndrome in the Trisomy 18 Stories section of this site. Some of these parents chose comfort care (as we did), some chose more aggressive intervention, some were born by c-section. In other words, the whole gamut of experiences is expressed and will help you see the possibilities for your child.
Where can I find support from other parents of children with Edwards Syndrome?
There are several sites with very good information and support about Edwards Syndrome:
How can I make a website for my child? There is a terrific website, T18Moms.com that contains a list of Websites for families of children with Edwards syndrome and offers help in creating websites for these children.
Although this is a very difficult situation, there is a lot of support available - you are not alone. I have also included a section of Grief Resources to help you grieve your child. This is a strange journey; in many ways the grieving starts at the diagnosis, even before we lose our children. I hope that this site can be of help to you as you travel this difficult path.