Earliest anomaly to be detected in ultrasound is:

Earliest anomaly to be detected in ultrasound is Anencephaly (as early by 10th week) Anencephaly in Ultrasound: Acrania Loosely arranged brain parenchyma Frog Eye Appearance Figure: Frog eye sign and irregularly outlined brain patter protruding freely into amniotic fluid is seen, with absence of cranial vault.