Abstract
This review article discusses microcephaly (MC) from the perspective of prenatal diagnosis. MC is defined as a head circumference measurement below the -3 standard deviation for gestational age. Suspected MC may inadvertently result from an incorrect fetal age or measurement, but may also be due to common etiologies such as open spina bifida, encephalocele, holoprosencephaly, infection, ...
Abstract
This review article discusses microcephaly (MC) from the perspective of prenatal diagnosis. MC is defined as a head circumference measurement below the -3 standard deviation for gestational age. Suspected MC may inadvertently result from an incorrect fetal age or measurement, but may also be due to common etiologies such as open spina bifida, encephalocele, holoprosencephaly, infection, aneuploidy or one of the rare true or syndromic microcephalies. Typical ultrasound signs of fetal MC are the flat forehead, the small anterior lobe, the reduced gyral pattern with a short corpus callosum, pseudo-craniosynostosis, dilated subarachnoid space, and often a discrepant head to abdominal circumference. Some forms of severe MC may be evident in midtrimester, while most cases of MC are not detectable until the third trimester or after birth. Diagnostic assessment should include the offer of a genetic workup to identify monogenic forms with a high risk of recurrence, e.g., due to autosomal recessive inheritance. The paper discusses prenatal and genetic diagnostic algorithms in pregnancies with fetal MC, which, in combination with new genetic tools, will hopefully also increase the yield of the diagnostic genetic workup.
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