====== Maternal serum alpha-fetoprotein ======

A high maternal [[serum alpha-fetoprotein]] (≥2 multiples of the median for the appropriate week of [[gestation]]) between 15 and 20 weeks gestation carries a relative risk of 224 for [[neural tube defect]]s, and an abnormal value (high or low) was associated with 34% of all major [[congenital defect]]s
((Milunsky A, Jick SS, Bruell CL, et al. Predictive Values, Relative Risks, and Overall Benefits of High and Low Maternal Serum Alpha-Fetoprotein Screening in Singleton Pregnancies: New epidemiologic data. Am J Obstet Gynecol. 1989; 161:291–297)).

The sensitivity of maternal serum AFP for [[spina bifida]] was 91% (10 of 11 cases), it was 100% for 9 cases of [[anencephaly]]. However, other series show a lower [[sensitivity]]. Closed lumbosacral spine defects, accounting for ≈ 20% of [[spina bifida]] patients,
((Burton BK. Alpha-Fetoprotein Screening. Adv Pediatr. 1986; 33:181–196))
will probably be missed by serum AFP screening, and may also be missed on [[ultrasound]]. Since maternal serum AFP rises during normal [[pregnancy]], an overestimate of gestational age may cause an elevated AFP to be interpreted as normal, and an underestimate may cause a normal level to be interpreted as elevated
((Bennett MJ, Blau K, Johnson RD, et al. Some Problems of Alpha-Fetoprotein Screening. Lancet. 1978; 2:1296–1297)).
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A 2nd-trimester maternal serum alpha-fetoprotein (MSAFP) level >3.8MoM in a [[fetus]] with an [[open neural tube defect]] (ONTD) is associated with mid-gestation [[ventriculomegaly]]
((Corroenne R, Zhu K, Orman G, Huisman TAGM, Mehollin-Ray AR, Johnson E, Johnson RM, Andrucioli A, Espinoza J, Nassr AA, Belfort M, Donepudi R, Shamshirsaz AA, Aagaard K, Whitehead WE, Sanz Cortes M. [[Maternal serum alpha-fetoprotein]] level and the relationship to [[ventriculomegaly]] in [[fetal neural tube defect]]: A retrospective cohort study. Eur J Obstet Gynecol Reprod Biol. 2021 Apr;259:185-190. doi: 10.1016/j.ejogrb.2021.02.010. Epub 2021 Feb 16. PMID: 33684673.)).

===== References =====