MANAGEMENT AND PROGNOSIS — The role of fetal surgery, route of delivery, pediatric management, and prognosis for children with these abnormalities are discussed separately. (See "Anencephaly and encephalocele" and see "Myelomeningocele").

Pregnancy complications — An elevated MSAFP level in the second trimester of pregnancy that cannot be explained (eg, presence of a fetal anomaly, maternal hepatocellular or ovarian tumor) is associated with an increased risk of subsequent fetal death. As an example, a case-control study of 612 women whose pregnancies ended in fetal death and 2501 women who gave birth to live infants reported that women with an MSAFP level 3.0 MoM had a 10-fold increase in risk of fetal death as compared to women who had a normal level and the risk remained high until term [55]. Elevated AFP levels were especially likely to be associated with fetal death in pregnancies complicated by hypertension.

In another series, a high MSAFP value was associated with the following adverse outcomes: neural tube defects (relative risk = 224), other major congenital defects (relative risk = 4.7), fetal deaths (relative risk = 8.1), neonatal death (relative risk = 4.7), low birth weight (relative risk = 4.0), newborn complications (relative risk = 3.6), oligohydramnios (relative risk = 3.4), abruptio placentae (relative risk = 3.0), and preeclampsia (relative risk = 2.3) [39].

The mechanism for poor pregnancy outcome in these cases may relate to defective placentation leading to higher than normal fetal to maternal AFP transport. Increased fetal surveillance has been suggested for these pregnancies, although the benefit of this intervention has not been demonstrated in controlled trials. (See "Pregnancy complications predicted by second trimester maternal serum screening").

SUMMARY AND RECOMMENDATIONS

Neural tube defects are the second most prevalent congenital anomaly in the United States, second only to cardiac malformations. Prenatal maternal serum screening programs for alpha fetoprotein (instituted in the 1970s and 1980s) combined with periconceptional folic acid supplementation and food fortification (instituted in the 1990s) have led to a decrease in the prevalence of neural tube defects where these interventions are practiced. (See "Incidence and epidemiology" above).
Occurrence of neural tube defects may be related to maternal folate deficiency (folate sensitive neural tube defects) or unrelated to maternal folate levels (chromosomal abnormalities, deformations, teratogens). (See "Etiology and risk factors" above).
We recommend maternal serum alpha-fetoprotein screening be offered to all pregnant women at 15 to 20 weeks of gestation (Grade 1B). It is an effective method for detecting neural tube defects and thus allows women the option of termination of an affected pregnancy or the opportunity to prepare for the birth of an affected child. (See "Screening" above).
AFP screening is primarily intended for the detection of open spina bifida and anencephaly, but can also uncover several nonneural fetal abnormalities (eg, ventral wall defects, tumors, dermatologic disorders, congenital nephrosis, aneuploidy). It does not detect closed spina bifida. A value above 2.0 to 2.5 MoM is designated an abnormal result.

A combination of ultrasound examination and amniocentesis (for acetylcholinesterase, alpha-fetoprotein, karyotype) should be performed in women with positive screen results. Detection rates for neural tube defects are greater than 95 percent with rare false positives with both of these modalities. (See "Prenatal diagnosis" above).
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