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Amniocentesis, also known as an Amniotic Fluid Test (AFT), is a diagnostic test usually undertaken between week 15 and week 20 of pregnancy, though it can be taken as early as week 11. It is a test in which about 20 mL of your amniotic fluid, which contains fetal tissues, is used to examine the DNA of the fetus.

Amniocentesis has an accuracy rate of 99% in diagnosing several possible birth defects including:

  • chromosomal abnormalities, such as Down syndrome and Turner syndrome among others,
  • neural tube defects, such as spinal bifida,
  • lung maturity,
  • sickle cell anemia,
  • infections,
  • Rh incompatibility and
  • decompression of polyhydramnios.

However, it cannot be used to test for structural defects, such as a cleft lip or palate.

Amniocentesis is a quick procedure that lasts for less than a minute. You can do it under local anesthetic if you choose, but this means 2 needles instead of one. Your physician, using an ultrasound for guidance, will then inject a needle into your lower abdomen, then your uterine wall and finally your amniotic sac, from which he will extract the fluid he needs to test. The puncture will heal and the amniotic fluid will be replenished within 24-48 hours and your results should be ready in a week or two.

However, amniocentesis is a very invasive test and it is best that only women pregnant with a baby who is at high-risk for any of the conditions mentioned above undergo this procedure. This risk is determined based on the mother’s age, the parents’ medical history and sometimes an AFP test.

Possible complications include:

  • miscarriage
  • preterm labour and delivery
  • respiratory distress
  • postural deformities
  • fetal trauma
  • amniotic fluid embolism
  • rhesus disease in the mother

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