<prompt> The earliest congenital anomaly identified by ultrasound is:HydrocephalusEncephaloceleSpina bifidaAnencephaly  <response>: Ans. d AnencephalyRef.: Nelson 18th ed.Ch. 592.6 Anencephaly is absence of cranial vault posteriorly with brain and meninges exposed.This condition can be detected by antenatal USG as early as 11-12 weeks. 