The Ewha Medical Journal
Ewha Womans University School of Medicine
Case Report

Anencephaly Diagnosed by Three-Dimensional Transvaginal Ultrasonography in the First Trimester of Pregnancy

Ji Eun Park, Hee Ok Kim, Mi Young Park, Young Ju Kim, Jung Ja Ahn, Bock Hi Woo

Copyright ⓒ 2000. Ewha Womans University School of Medicine. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Published Online: Sep 30, 2000


Neural tube defects are a heterogenous group of malformations resulting from failure of neural tube closure during early embryogenesis. Anencephaly is the commonest form of neural tube defect and results from failure of closure of the anterior portion of the neural tube. Anencephaly is characterized by absence of the cranium along with cerebral hemispheres that are rudimentary or absent and risk of recurrence after affected child is 2-3%. Periconceptual folic acid intake may decrease the incidence and recurrence of anencephaly.

Most often, anencephaly is discovered by conventional two-dimensional ultrasonography at the time of attempted biparietal diameter determination for fetal age in the second trimester. Two-dimensional transvaginal ultrasonography has a limitation in a motion of the transducer shaft due to narrow space of the vagina. It is sometimes impossible to obtain information of the whole brain and to miss the fetal CNS(central nervous system) anomalies. Recent advanced three-dimensional ultrasonography has remarkably improved not only surface rendering but also multiplanar analysis of internal structure.

Recently, we encountered one case of recurrent anencephaly that had occurred in a same pregnant woman and three-dimensional transvaginal ultrasonography enabled us to diagnose anencephaly at 113 weeks of gestation. We report this case with brief review of the literatures.

Keywords: Neural tube defect; Anencephaly; Folic acid; Three-dimensional ultrasonography