What should a woman do who married a man with children, stipulated that she wanted to have children with him, but has not been blessed with a child by him, and he refuses medical examination, claiming that he has had children before?

The wife either stipulated procreation in any case, and this is an invalid condition because it stipulates something that is not within the creature's ability, or her condition was that he take the necessary measures to procreate by seeking treatment. This latter condition does not contradict the purpose of marriage, based on the Prophet's (peace be upon him) saying: "Marry the affectionate, fertile woman, for I will boast of your numbers before the nations," and his saying: "Seek medical treatment, for Allah Almighty has not created a disease without also creating a cure for it, except for one disease: old age."

It is the husband's duty, and his wife's right upon him, to undergo appropriate examinations and treatments. If he does so and procreation does not occur, he is not required to do more. But if he refuses treatment, she has the right to seek divorce.