Amniotic fluid is obtained by amniocentesis under ultrasound control. After infiltrating the anterior abdominal wall with local anaesthetic a fine needle is inserted into the amniotic sac. If the placenta is anterior, it may be necessary to traverse it to reach the amniotic fluid. Amniotic fluid is used (a) for prenatal diagnosis including fetal karyotype, alphafetoprotein levels and to diagnose metabolic abnormalities after 15 weeks’ gestation and later in pregnancy; (b) to diagnose the severity of rhesus disease and (c) to determine if the fetal lungs are mature. Complications include a 0.5%–1% miscarriage rate and rarely postural deformities, e.g., talipes. Rhesus-negative women should have a Kleihauer test after the procedure and receive 50 μg of anti-D to cover fetomaternal transfusion. Amniocentesis may also be a therapeutic procedure, e.g. intra-amniotic instillation of thyroxine in fetal goitre; repeated drainage amniocentesis in twin-twin transfusion.
KeywordsProstaglandin Nylon Perforation Hydrocephalus Infertility
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