For amenorrhea due to gonadal dysgenesis, what is the definitive diagnostic test?

For amenorrhea due to gonadal dysgenesis, what is the definitive diagnostic test?

• A. Ultrasound
• B. Karyotyping
• C. Serum progesterone
• D. MRI pelvis

Answer: (B)

Gonadal dysgenesis causing amenorrhea is rooted in chromosomal abnormalities, so confirming the diagnosis depends on analyzing the chromosomes. Karyotyping directly reveals the genetic makeup (such as monosomy X or mosaic Turner variants) that underlies streak ovaries and ovarian failure, guiding prognosis, associated anomaly screening, and hormone management decisions. Imaging such as ultrasound or MRI can show the anatomy—whether ovaries are nonfunctional or absent—but they do not identify the genetic cause. Serum progesterone can assess ovarian function at a functional level but does not establish the chromosomal basis of the condition. Thus, the definitive test is karyotyping, because it provides the essential genetic confirmation needed for diagnosis and management.

Gonadal dysgenesis causing amenorrhea is rooted in chromosomal abnormalities, so confirming the diagnosis depends on analyzing the chromosomes. Karyotyping directly reveals the genetic makeup (such as monosomy X or mosaic Turner variants) that underlies streak ovaries and ovarian failure, guiding prognosis, associated anomaly screening, and hormone management decisions. Imaging such as ultrasound or MRI can show the anatomy—whether ovaries are nonfunctional or absent—but they do not identify the genetic cause. Serum progesterone can assess ovarian function at a functional level but does not establish the chromosomal basis of the condition. Thus, the definitive test is karyotyping, because it provides the essential genetic confirmation needed for diagnosis and management.