We’d like to clarify that the time of the `umrah is very short and should not be a problem. A woman should arrange to travel to perform `Umrah while she is clean. If she cannot or that she has irregular or long period, then she should act according to the following.
A menstruating woman can perform all acts of Hajj and `Umrah save Tawaf which she has to do after she gains purity from her menstruation. So, she can make ghusl (bath) and intends ihram without performing prayer and then wait until she is purified. Then she can perform tawaf and sa`i.
If she is forced to leave Makkah because of travel arrangements that she cannot change at all, she is allowed to make Tawaf and sa`i after applying sanitary towel.