A client who is 15 weeks pregnant comes to the clinic for amniocentesis. Which finding can identify neural tube defects?

A client who is 15 weeks pregnant comes to the clinic for amniocentesis. Which finding can identify neural tube defects?

• A. Fetal lung maturity
• B. Amniotic fluid volume
• C. Placental position
• D. Neural tube defects

Answer: (D)

The concept being tested is how neural tube defects are identified during amniocentesis. Open neural tube defects in the fetus are best detected by analyzing amniotic fluid for markers that reflect fetal leakage or abnormal development. The classic finding is the presence of neural tube defect indicators in the amniotic fluid, most notably elevated alpha-fetoprotein (AFP) and acetylcholinesterase, which point to an open defect such as anencephaly or open spina bifida. These markers directly signal an NTD rather than other unrelated aspects of pregnancy. The other listed findings—fetal lung maturity, amniotic fluid volume, and placental position—do not diagnose neural tube defects; they pertain to lung develop­ment, fluid balance, or placental placement and are not specific for NTDs. Therefore, identifying a neural tube defect in the fetus is the finding that best confirms the condition.

The concept being tested is how neural tube defects are identified during amniocentesis. Open neural tube defects in the fetus are best detected by analyzing amniotic fluid for markers that reflect fetal leakage or abnormal development. The classic finding is the presence of neural tube defect indicators in the amniotic fluid, most notably elevated alpha-fetoprotein (AFP) and acetylcholinesterase, which point to an open defect such as anencephaly or open spina bifida. These markers directly signal an NTD rather than other unrelated aspects of pregnancy. The other listed findings—fetal lung maturity, amniotic fluid volume, and placental position—do not diagnose neural tube defects; they pertain to lung develop­ment, fluid balance, or placental placement and are not specific for NTDs. Therefore, identifying a neural tube defect in the fetus is the finding that best confirms the condition.