BACKGROUND: The amniotic band syndrome is a collection of fetal malformations 
associated with fibrous bands that appear to entrap or entangle various fetal 
parts in utero and can affect any organ or system and cause a single or multiple 
anomalies. The anomaly, acrania, is characterized by partial or complete absence 
of the calvarium with abnormal brain tissue development. Literature reports 
association of amniotic band syndrome and acrania postnatally, but not diagnosed 
prenatally by ultrasound.
CASE: A young woman, gravida 1, para 0, presented for an initial prenatal visit 
at 35 weeks' gestation and had a first ultrasound that showed a single 
intrauterine pregnancy at 36 weeks' gestation. This ultrasound also showed 
polyhydramnios, absence of or a very small cerebrum with either anencephaly or 
acrania. A targeted ultrasound scan was performed on the following day, which 
confirmed acrania in view of the fact that we did see an absence of the flat 
bones of the skull with a substantial amount of abnormal brain tissue present 
surrounded by a fetal membrane. The patient was counseled, and labor induction 
was scheduled with a male infant delivered weighing 1763 g after a spontaneous 
vaginal delivery. The infant was diagnosed with acrania, given supportive care, 
and died 11 hours later.
CONCLUSION: Diagnosis of cranial bone defects can be established by ultrasound 
in the first trimester of pregnancy. The prenatal diagnosis of acrania 
associated with amniotic bands by transvaginal ultrasound was visualized in the 
third trimester in this case; therefore, appropriate counseling and treatment 
options were offered.