What should a woman do if she is unsure about the type of blood coming from her, whether it is menses (hayd) or irregular bleeding (istihada)? Should she continue her acts of worship or wait until she is certain?

If a woman is uncertain whether the blood she sees is menstruation (hayd) or abnormal uterine bleeding (istihada), she should consult scholars and act upon their guidance. The general rule is that any blood a woman sees is menstrual blood if it occurs during a period suitable for menstruation. It is only considered abnormal uterine bleeding if it occurs at a time unsuitable for menstruation, such as if its duration exceeds fifteen days, or if it appears after less than the minimum period of purity, or if it is seen by a pregnant woman, or a young girl who is not typically expected to menstruate.