Why is an amniocentesis performed?

Amniocentesis is a procedure in which a needle is inserted into a pregnant woman's womb and fluid is obtained from around the baby. There are several times that an amniocentesis is appropriate. An amniocentesis is used for genetic evaluation to look for chromosome problems. The most common chromosome problem that's evaluated and picked up with an amniocentesis is trisomy 21 or Down syndrome. The problem is that there are complications that can occur with an amniocentesis. If the complication occurs when the genetic screen is done at 18 weeks or 17 weeks, unfortunately the pregnancy is lost. In this day and age, while it's unfortunate, there are normal pregnancies that are lost in the attempt to find Down syndrome or trisomy 21.

The other time that amniocentesis is commonly used is if we feel a mom probably should be delivered but we're not 100% sure, she's not quite due but she is close and we want to determine whether or not the baby's lungs are ready. This amniocentesis is a lot less of a risk, because if something does happen we can just deliver the mom. Amniocentesis tests are currently all done with ultrasound guidance, so the procedure is getting safer, but it is an invasive procedure. It does require putting a needle into mom's tummy and getting fluid from around the baby.