NBME Form 9 Practice Test

The key idea is the progesterone (progestin) withdrawal test used to evaluate estrogen status and endometrial integrity. If progesterone is given and a withdrawal bleed occurs after stopping it, the endometrium was adequately primed by estrogen and the amenorrhea is due to anovulation. If there is no withdrawal bleed, the endometrium didn’t proliferate, which points to insufficient estrogen or a uterine/outflow tract problem that prevents shedding. Therefore, the most likely cause is a situation where either estrogen deficiency or a structural/uterine abnormality is preventing the bleed. Options that reflect estrogen deficiency or uterine/structural issues fit best, whereas pregnancy or pure ovarian failure without considering the estrogen/uterine context would not as directly explain a lack of withdrawal bleed in this scenario.