Ghusl is invalid if performed while menses has not yet ceased completely. Purity is confirmed either by the appearance of a white discharge or complete dryness (no discharge). If Ghusl is performed before confirming purity, then the Ghusl must be repeated for prayers to be valid. However, if a woman becomes certain of her purity before Fajr (even without repeating ghusl), her fast for that day remains valid.

If someone thinks that he had a wet dream, then he wakes up and does not find any wetness, he does not have to do Ghusl.

If Ghusl does not meet these conditions, it is broken: 1- intention to remove impurity, 2- purity of water, 3- the water should reach the entire body, 4- continuity between the parts of Ghusl and not allowing any lengthy interruption between them.