Amniocentesis – Why is it needed during pregnancy?

vaginal bleeding

Amniocentesis also called as Amniotic fluid test is a prenatal test to detect various medical conditions in the fetus. Amniotic fluid is a watery substance surrounding the fetus which provides protection and information about the baby’s health inside the uterus. During the test, a fine thin needle is inserted into the abdomen and a sample of amniotic fluid is drawn from the uterus under ultrasound guidance without hurting the baby. This sample will be sent to lab for testing on various genetic disorders.

Why is it performed?

Amniocentesis is performed to test the presence of birth defects such as Down syndrome (chromosomal disorder), sickle cell anemia, muscular dystrophy, cystic fibrosis, spina bifida, Tay-Sachs etc.

It is usually performed if the expectant mother shows the following signs:

  • Family history of above mentioned birth defects
  • Pregnancy after 35 years of age
  • Previous child with birth defects
  • Abnormal ultrasound

When is it performed?

It is usually performed between week 16 and week 18 to ensure the absence of birth defects in baby. Sometimes, the test is also performed in the last trimester to check the growth and maturity of the fetal lung. The test results might take up to 12 -15 days for processing. The amniocentesis results are 99.4% accurate and it is completely harmless for the mother and the baby inside the womb.

How is it performed?

During the test, a small area of the abdomen is cleansed to avoid infection and local anesthesia will be given to ease the pain if required. Through ultrasound, the doctor will locate the position of the fetus and the placenta and then safely insert a long thin needle in to the uterus through abdomen without disturbing the baby. With ultrasound guidance, the doctor can insert the needle in to the uterus far away from the baby. A small amount of amniotic fluid will be drawn and sent to the lab for testing. You may feel the amniocentesis pain like a minor menstrual cramp during the procedure and it may last for few more hours. If the pain prolongs or if you experience any other symptom like bleeding or vaginal discharge, consult your gynecologist.


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