Are small drops of blood that continue for 16 hours a day, followed by fewer drops on subsequent days, considered menstruation?

If a woman sees blood after the duration of her usual period, it is added to her previous period and is considered menstruation if the total duration of both blood flows does not exceed fifteen days. If the total number of days exceeds fifteen days, and there was no sufficient period of purity in between, then she is considered to be experiencing irregular bleeding (istihada). However, if she experiences a period of purity for thirteen days and then sees drops of blood, it is not considered menstruation unless the total duration of these drops reaches a day and a night; otherwise, it is irregular bleeding.