UPSC-CMS 2022 — Obstetrics and Gynecology

Q: Determination of alpha-fetoprotein levels in maternal serum is a useful screening tool for

neural tube defects. ***Correct: neural tube defects*** - Elevated maternal serum **alpha-fetoprotein (AFP)** is a key indicator for open **neural tube defects** because the fetal tissue leaks AFP into the amniotic fluid and then into the maternal circulation. - This screening tool is sensitive enough to detect conditions like **spina bifida** and **anencephaly**. - Typically performed at **15-20 weeks gestation** as part of the triple or quad screen. *Incorrect: Duchenne muscular dystrophy* - This is a **genetically inherited X-linked recessive disorder** primarily diagnosed through genetic testing or muscle biopsy, not maternal serum AFP levels. - While **creatine kinase (CK)** levels can be elevated in affected individuals, it is not a prenatal AFP screening target. *Incorrect: phenylketonuria* - **Phenylketonuria (PKU)** is an inborn error of metabolism, typically screened for postnatally using a **newborn heel prick test** to detect elevated phenylalanine levels. - Maternal serum AFP is not used for its detection; the condition is managed by a special diet. *Incorrect: congenital hypothyroidism* - **Congenital hypothyroidism** is identified through **newborn screening programs** that measure levels of **thyroid-stimulating hormone (TSH)** or **thyroxine (T4)** from a heel prick. - Maternal serum AFP has no role in the screening or diagnosis of this condition.

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Q31

Determination of alpha-fetoprotein levels in maternal serum is a useful screening tool for