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• Prenatal Care

Let’s Talk Pregnancy Testing: Amniocentesis

Mothers receiving regular prenatal care know that pregnancy can involve lots of prenatal tests — and for good reason! They’re poked and prodded throughout their pregnancy so that doctors can determine the health of their baby. 

Amniocentesis is a little different. Instead of testing the mother — her blood, urine or heart rate, which are screening tests — this is a diagnostic test that involves taking a sample of amniotic fluid from the amniotic sac that surrounds and contains the baby inside her womb. With a sample of amniotic fluid, doctors can diagnose many serious conditions that may be affecting the baby.

When is Amniocentesis Recommended?

Though amniocentesis is considered safe, it is an invasive procedure that includes some inherent risk. That’s why amniocentesis is typically recommended only when other risk factors are present, such as any of the following

• The mother is at increased risk for a chromosomal or genetic disorder, most commonly based upon a prenatal screening test
• The mother or father has a family history of a genetic condition 
• Prenatal ultrasound has detected potential abnormalities 

What Does Amniocentesis Look For?

Amniocentesis can diagnose several hundreds of chromosome abnormalities and genetic disorders, including:

• Down syndrome
• Tay-Sachs
• Sickle cell disease

In most cases, amniocentesis is performed between weeks 15 and 20 of a pregnancy. Less commonly, amniocentesis may be used in the third trimester to check for infections, anemia and lung health in special circumstances.

With a sample of amniotic fluid, doctors can diagnose many serious conditions that may be affecting the baby.

What are the Risks of Amniocentesis?

Amniocentesis is generally considered to be a safe procedure, but it is an invasive diagnostic test that has some inherent risks, the primary one being miscarriage. A miscarriage after amniocentesis can occur for any of the following reasons:

• Uterus infection
• Water breaking
• Labor induced prematurely

It is possible, though it is extremely rare, for the baby to come into contact with the needle during the procedure. Medical professionals use an ultrasound while performing this procedure to determine the baby’s position to keep this from happening.

The mother may experience the following side effects:

• Cramping
• Leaking fluid
• Pain from needle entering skin, then uterus
• Minor irritation at puncture site

While minor cramping may be normal after a procedure, call your doctor if you experience any of the following:

• Fever above 100.4°F 
• Chills
• Bright red vaginal bleeding 
• Foul smelling vaginal discharge
• Contractions or severe cramping
• Continuous liquid vaginal discharge 
• Decreased movement of the baby if the amniocentesis is done late in pregnancy

Source: American Pregnancy Association; What to Expect