This article is from the Pregnancy Screening FAQ, by Lynn Gazis-Sax (gazissax@netcom.com) with numerous contributions by others.
2.f No. The screening process will detect 80% of the cases of spina bifida
and 90% of the cases of anencephaly.
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Addition by Dr. Tim Reynolds:
Hence the argument for a detailed ultrasound scan at 18 weeks (routine UK
practice in most good centres is a dating scan either at booking (8-12
weeks), or when the Down's test is collected (16 weeks): PLUS, a detailed
'anomaly scan' at 18-20 weeks.
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