This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
A woman with amenorrhea is having negative progesterone challenge test but has bleeding on combined estrogen-Progesterone challenge. What can be the cause - 
Select and explain. 
A. Anovulation, B. Asherman syndrome, C. Pregnancy, D. Pituitary tumor
D: Pituitary tumor
Answer: D: Pituitary tumor 
Explanation: Ans. is 'd' i.e., Pituitary tumor Negative progesterone challenge test - which rules out PCOD - (otherwise too, PCOD is a cause of secondary amenorrhea).When next step was done i.e., estrogen, progesterone combined test - It comes out to be positive i.e., compament I system (uterus, endometrium and outflow tract) is normal if properly stimulated by estrogen which rules out mullerian agenesis and ashermann syndrome.Positive estrogen progesterone combined test means the defect is in the production of estrogen i.e., either ovaries, pituitary or hypothalamus.