B’sha’ah tovah!
Looking at toilet paper can sometimes cause a woman to become niddah unnecessarily. Therefore, women are often advised to avoid looking.
On the other hand, as you write, it’s important for a woman to know what’s going on with her body, especially since bleeding sometimes indicates a medical problem that requires attention.
There is no halachic prohibition against looking at toilet paper. Furthermore, we follow the halachic position that if a woman waits a few seconds after urinating before wiping, any blood she finds on toilet paper does not make her niddah. Therefore, we recommend that a woman who wishes to check toilet paper wait at least a few seconds (ideally 15 seconds) after urinating before wiping. (A woman should still be careful to avoid looking into the toilet while urinating, because if she sees blood or discharge of a niddah color exiting her body it may render her niddah.)
Please see our article on Toilet Paper for a more detailed discussion of this halacha.
A woman can choose whether or not to look based on her situation. For example, a woman starting a new birth control pill that may cause staining at the beginning might want to avoid looking altogether. On the other hand, a woman who is pregnant and is not expecting uterine bleeding might want to check the toilet paper every now and then — after waiting — in order to ensure that there is no bleeding.
You did not ask specifically about your current status, but we want to be clear that if your doctor confirmed that s/he saw a wound on the cervix, you may attribute the blood you saw on the toilet paper to dam makkah, and it did not render you niddah.
Please write back with any further questions.
B’Hatzlacha!
This response was updated 18 February, 2024.