A 35 year old female, mother of a Down's syndrome child, became pregnant. Amniocentesis is done to rule out Down's syndrome in the second child. What is the appropriate time for doing amniocentesis?
6-Apr
12-Aug
17-Dec
20-28
Amniocentesis generally is carried out at 15 to 17 weeks of gestation but can be offered earlier (12-14 weeks). The underlying risk of amniocentesis when performed at 15 weeks of gestation and beyond is increased risk of miscarriage. This risk is estimated at 1 in 200 (0.5%). Ref: Manipalviratn S., Trivax B., Huang A. (2007). Chapter 5. Genetic Disorders & Sex Chromosome Abnormalities. In A.H. DeCherney, L. Nathan (Eds),CURRENT Diagnosis & Treatment Obstetrics & Gynecology, 10e.