Primary amenorrhea is defined as the absence of menarche by what age?

• A. No menses by age 18.
• B. No menarche by age 15.
• C. No menses after age 25.
• D. Menarche occurs before age 10.

Answer: (B)

Primary amenorrhea means a person hasn’t started having periods by the age when puberty should be complete. In typical development, pubertal changes begin with breast development and then menarche around age 12–13. If menses have not begun by age 15, it’s classified as primary amenorrhea, even if other signs of puberty are present. If there are no secondary sexual characteristics, some guidelines use age 13 as the cutoff. The other options don’t fit this definition: waiting until 18 delays evaluation beyond the standard threshold, waiting until 25 reflects a different scenario (cessation after starting periods), and having menarche before age 10 is simply early menarche, not the absence of menarche.