RESUMO
The authors report on 18 cases of anencephalus, studied from April, 1976 to December, 1982. Possible etiologies, morphological characteristics, circumstances leading to its discovery, and diagnostic tools are presented. Emphasis is placed on the usefulness of ultrasonography to diagnose this condition as early as the 13th to 14th week of gestation. Evacuation of the uterus is always difficult as it involves a second trimester abortion, but is one of the best indications for the use of prostaglandins. In a woman with a previous history of an anencephalic child, careful monitoring of subsequent pregnancies is necessary as the recurrence rate is approximately 4 p. 100 (13 p. 100 in the case of a second anencephalic child). Dosing of alpha-fetoprotein and acetylcholinesterase in amniotic fluid and repeated sonograms are indispensable.