AFP is elevated in which of the following conditions?

Appeared in: JIPMER Nursing Officer - 2020

Explanation

Alpha-fetoprotein (AFP) is a key protein marker used in prenatal screening, produced by the fetal yolk sac and liver.
Gastroschisis is an open abdominal wall defect where the fetal intestines are directly exposed to amniotic fluid without a protective sac.
This direct exposure allows large amounts of AFP to leak into the amniotic fluid and then into the maternal circulation, causing markedly elevated maternal serum AFP (MSAFP) levels.
The absence of a covering membrane is the key feature that distinguishes it from omphalocele and explains the significant AFP elevation.

Option A: In an omphalocele, the herniated abdominal organs are covered by a protective sac (peritoneum and amnion). This sac limits the leakage of AFP into the amniotic fluid.
Option C: Down syndrome (Trisomy 21) is a chromosomal abnormality that is characteristically associated with LOW levels of maternal serum AFP.
Option D: Spina bifida occulta is a 'closed' neural tube defect, meaning it is covered by skin. Because there is no open lesion, AFP does not leak into the amniotic fluid.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Interpretation of maternal serum alpha-fetoprotein (MSAFP) levels in prenatal screening as background academic context rather than a clinical decision trigger.
A nurse's role includes educating expectant parents about prenatal screening tests like the MSAFP. It is crucial to explain that it is a screening test, not a diagnostic one, and abnormal results require further investigation.
If MSAFP is elevated, the nurse should prepare the patient for follow-up tests, which typically include a detailed ultrasound to look for defects and possibly an amniocentesis.
Counseling should be provided in a non-directive manner, offering support and clear information to help parents make informed decisions about their pregnancy.

How to Approach the Question

First, identify the key term in the question: 'AFP is elevated'.
Recall the function of AFP as a fetal protein and its use as a maternal serum marker for fetal anomalies.
Systematically evaluate each option based on its pathophysiology:
Omphalocele: Is it an open or closed defect? (Closed, sac-covered)
Gastroschisis: Is it an open or closed defect? (Open, no sac)
Down syndrome: Is it associated with high or low AFP? (Low)

Concept Tested & Keywords

Concept Tested: Interpretation of maternal serum alpha-fetoprotein (MSAFP) levels in prenatal screening
Stem keywords: AFP, elevated
Lead-in keywords: which of the following
Negative lead-in flag: false

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E6 Obstetrics Williams pp. 29-48, 30-50

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Attempt every question from this paper in a timed mock, then review the full solution for each one.