Amniocentesis – How Does the Procedure Work?

An amniocentesis procedure can be done in the doctor’s office by a high-risk pregnancy doctor called a perinatologist. Amniocentesis is an outpatient procedure, meaning you can usually go home soon afterward. Most women find that it can be uncomfortable and many compare it to having intense menstrual cramps, but generally do not experience considerable pain beyond that.

The point of the procedure is usually to obtain fluid from around the pregnancy to send to the lab for testing. The lab can look at cells from the pregnancy that are floating in the fluid, and inside those cells at the chromosomes. To learn more about chromosomes, visit our Genetics 101 page.

To start with, generally an ultrasound technician will perform an ultrasound to allow the doctor to find a pocket of fluid that is furthest away from the pregnancy. With the ultrasound on the entire time, the doctor inserts a small needle into the abdomen (not through the belly button), through the uterus, and into the sac that the pregnancy is in. Once the needle is in the sac, a syringe is attached to the end and fluid is drawn out and sent to the lab.

Because the uterus is a muscle, some women may notice intense cramping during and immediately after the procedure. Some people have concerns about the needle poking the baby; the ultrasound is constantly monitoring where the baby is to ensure that they do not get close to the needle. Most doctors also use a plastic catheter to remove the fluid after they have gotten into the sac, so if the baby were to brush up against the tube it would not cause any harm.

Because amniocentesis is an invasive procedure, there is an approximated less than 1 in 200 (0.5%) chance that it may cause complications that could lead to a miscarriage. This also means that over 99.5% of women who undergo amniocentesis testing do not have a procedure-related miscarriage. To help limit the risk for complications, your doctor may give you special instructions to limit strenuous physical activity for the few days following your procedure.

Depending on the type of testing that is performed, amniocentesis can look for chromosome conditions, such as Down syndrome, or other genetic conditions, but cannot rule out all birth defects or genetic conditions.

Click here to learn more about scheduling a genetic counseling appointment for pregnancy-related questions.

Related Articles

  • The type of results may vary depending on the type of testing that is done on the amniocentesis sample. The four main types of testing that can be done on amniocentesis samples are: traditional chromosome analysis (also called a karyotype), chromosomal microarray, familial mutation testing, and fluorescent in-situ hybridization (FISH).…
  • This can be difficult news to hear, and everyone handles situations like this in different ways. It is often helpful to talk with your doctor or genetic counselor to make sure any questions that you have are answered, particularly if the results are complex or confusing. Even if you are…
  • The decision of whether or not to have a diagnostic test, such as amniocentesis, can be a difficult decision to make. Your genetic counselor can help answer any questions, and help you come to the decision that is best for your personality, beliefs, and values. Some things that may be…

Last updated on Aug 21st, 2019

Ready to learn more?


Schedule a personalized consultation with one of our certified genetic counselors.


Schedule here