Second trimester scan for fetal anomalies. History of neural defect in previous pregnancy and history of consanguinity present
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The cranium or skull vault is absent with exposed neural tissue. The fetus has 'frog face' appearance.
Acrania is the failure of calvarial mesenchymal migration under the calvarial ectoderm resulting in the absence of development of osseous cranium, scalp muscles and dura 1. Also there is failure of formation of two lobes in cerebrum. The exposure of cerebral hemispheres is called as exencephaly. Prolonged exposure of the neural tissue results in repetitive mechanical and chemical trauma to the tissue resulting in damage and distortion and finally anencephaly 2.
- 1. Mannes EJ, Crelin ES, Hobbins JS et-al. Sonographic demonstration of fetal acrania. AJR Am J Roentgenol. 1982;139 (1): 181-2. doi:10.2214/ajr.139.1.181 - Pubmed citation
- 2. Cafici D, Sepulveda W. First-trimester echogenic amniotic fluid in the acrania-anencephaly sequence. J Ultrasound Med. 2004;22 (10): 1075-9. Pubmed citation