Following the introduction of transvaginal sonography several first trimest
er diagnoses of the exencephaly anencephaly sequence have been reported wit
h the earliest being described at 10 weeks of gestation. We report a case w
ith a high index of suspicion for exencephaly as 9 weeks and 3 days because
of three sonographic features: the cranial pole of the embryo was smaller
than the chest, the cranial pole bulged dorsally and the surface of the cra
nium was irregular The diagnosis was confirmed by a repeat ultrasound exami
nation at 11 + 4 weeks and by autopsy after termination of pregnancy.