Which one of the following congenital malformations of the fetus can be diagnosed in the first trimester by ultrasound?: (A) Anencephaly, (B) Dysplastic kidneys, (C) Microcephaly, (D) Holoprosencephaly
Answer is A. Ultrasound done in the first trimester helps in dating the pregnancy. Malformations are best looked for at 18-20 weeks of gestation. If there is a malformation that is not ble with a normal life, then a decision to do a termination of pregnancy can be taken at this time ( In India: MTP only <= 20 weeks) However, in the first trimester, i.e., around 9-11 weeks, gross malformations of the fetus like anencephaly, Acrania or spina bifida can be picked up. To detect specific deformities like holoprosencephaly or microcephaly, USG is to be done at 18-20 weeks of gestation and not in the first trimester.