Amniocentesis: Necessary Information or Unnecessary Risk?
Pros
Reasons to have an amniocentesis are many, but the biggest is probably that the test gives you a reasonably conclusive answer as to whether your baby has a serious chromosome disorder. With a 99.4% accuracy rate, the odds are low that your amniocentesis will give you a false positive or negative for a chromosome disorder.
For parents who would choose to terminate pregnancies with chromosome disorders, the accuracy of amniocentesis is a strong pro in favor of having the test. In addition, despite the common association with Down syndrome screening, an amniocentesis can also confirm or rule out several disorders with a worse prognosis than Down syndrome. It is possible that parents who would not choose to terminate a baby with Down syndrome would consider termination if an amniocentesis revealed a condition with high odds of causing death in early infancy, such as Edwards syndrome or triploidy. In such cases, an amniocentesis can be a reliable way to distinguish which chromosome disorder the baby actually has in the event that a screening test or ultrasound shows nonspecific cause for concern over chromosome disorders.
Finally, regardless of people's feelings on termination, an amniocentesis can help parents and doctors to prepare themselves to deal with a baby's needs at birth. Even parents who would not terminate a pregnancy may prefer to have advance knowledge of the baby's diagnosis so they can research the condition and know what to expect at birth.
Cons
The main argument against amniocentesis is the small added risk of miscarriage. There is a lot of conflicted reporting over the actual numbers, but even the accepted estimate of 1 in 400 might be too scary for some moms -- especially those with a history of miscarriage or infertility. Even moms who receive triple and quad screen results showing a higher odds of chromosome disorders may opt against amniocentesis for this reason.
Because of religious or philosophical beliefs, some moms may feel they would not consider terminating a pregnancy for any reason -- even if the baby had a fatal congenital disorder. With termination being out of the question, these moms may decide that there is no benefit to having an amniocentesis since it would carry a small risk and would not change the outcome.
Where It Stands
It is possible that future research may make the whole debate irrelevant. Researchers are actively at work on less invasive tests to screen for chromosome disorders in developing babies, such as by isolating the baby's genetic material from samples of the mother's blood. Time will tell what comes of those efforts, but for now, amniocentesis is what's available.
Using the correct numbers for the risk of miscarrying after an amniocentesis, the natural conclusion would seem to be that moms whose risk of having a baby with a chromosome disorder is less than 1 in 400 should not have an amniocentesis (since the odds of the test causing a miscarriage would be higher). Moms whose risk of having a baby with a chromosome disorder is higher than 1 in 400, whether due to age or triple/quad screen results, should have the option of having the test done. As with most questions, moms should work with their doctors to make decisions that best fit their philosophical beliefs and medical circumstances.
Sources:
Amniocentesis. American Pregnancy Association. Accessed: Apr. 21, 2009. http://www.americanpregnancy.org/prenataltesting/amniocentesis.html.
Should I have an amniocentesis? CIGNA. Accessed: Apr. 21, 2009. http://www.cigna.com/healthinfo/aa103080.html.
Reasons to have an amniocentesis are many, but the biggest is probably that the test gives you a reasonably conclusive answer as to whether your baby has a serious chromosome disorder. With a 99.4% accuracy rate, the odds are low that your amniocentesis will give you a false positive or negative for a chromosome disorder.
For parents who would choose to terminate pregnancies with chromosome disorders, the accuracy of amniocentesis is a strong pro in favor of having the test. In addition, despite the common association with Down syndrome screening, an amniocentesis can also confirm or rule out several disorders with a worse prognosis than Down syndrome. It is possible that parents who would not choose to terminate a baby with Down syndrome would consider termination if an amniocentesis revealed a condition with high odds of causing death in early infancy, such as Edwards syndrome or triploidy. In such cases, an amniocentesis can be a reliable way to distinguish which chromosome disorder the baby actually has in the event that a screening test or ultrasound shows nonspecific cause for concern over chromosome disorders.
Finally, regardless of people's feelings on termination, an amniocentesis can help parents and doctors to prepare themselves to deal with a baby's needs at birth. Even parents who would not terminate a pregnancy may prefer to have advance knowledge of the baby's diagnosis so they can research the condition and know what to expect at birth.
Cons
The main argument against amniocentesis is the small added risk of miscarriage. There is a lot of conflicted reporting over the actual numbers, but even the accepted estimate of 1 in 400 might be too scary for some moms -- especially those with a history of miscarriage or infertility. Even moms who receive triple and quad screen results showing a higher odds of chromosome disorders may opt against amniocentesis for this reason.
Because of religious or philosophical beliefs, some moms may feel they would not consider terminating a pregnancy for any reason -- even if the baby had a fatal congenital disorder. With termination being out of the question, these moms may decide that there is no benefit to having an amniocentesis since it would carry a small risk and would not change the outcome.
Where It Stands
It is possible that future research may make the whole debate irrelevant. Researchers are actively at work on less invasive tests to screen for chromosome disorders in developing babies, such as by isolating the baby's genetic material from samples of the mother's blood. Time will tell what comes of those efforts, but for now, amniocentesis is what's available.
Using the correct numbers for the risk of miscarrying after an amniocentesis, the natural conclusion would seem to be that moms whose risk of having a baby with a chromosome disorder is less than 1 in 400 should not have an amniocentesis (since the odds of the test causing a miscarriage would be higher). Moms whose risk of having a baby with a chromosome disorder is higher than 1 in 400, whether due to age or triple/quad screen results, should have the option of having the test done. As with most questions, moms should work with their doctors to make decisions that best fit their philosophical beliefs and medical circumstances.
Sources:
Amniocentesis. American Pregnancy Association. Accessed: Apr. 21, 2009. http://www.americanpregnancy.org/prenataltesting/amniocentesis.html.
Should I have an amniocentesis? CIGNA. Accessed: Apr. 21, 2009. http://www.cigna.com/healthinfo/aa103080.html.
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