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Surgical insertion of a hollow needle through the abdominal wall into the uterus of a pregnant female to extract fluid from the amniotic sac for analysis of fluid and fetal cells. This can reveal the fetus's sex (important when sex-linked genetic disease is possible), chromosomal disorders, and other problems. First performed in the 1930s, amniocentesis is generally done under local anesthesia in the 15th–17th week of gestation.
This entry comes from Encyclopædia Britannica Concise. For the full entry on amniocentesis, visit Britannica.com.