2,055. Bleeding During Intimacy
Hilchos Issurei Biah 4:19
If a woman cleaned herself with a cloth that was checked but she then touched her thigh with it and the next day found blood upon it, she is ritually unclean. We don’t suggest that a louse might have been crushed when she touched her thigh with the cloth. If she cleaned herself with a cloth that wasn’t checked and she didn’t know whether or not there was blood on the cloth before she used it to clean herself, then if there was more than a gris of blood on it [about the size of a dime], she is a niddah; less than that, she is ritually clean and we assume that the blood came from a louse.
Hilchos Issurei Biah 4:20
If a woman bleeds vaginally during intimacy, she is allowed to be intimate again after being purified. If she bleeds during intimacy a second time, she may be intimate a third time. If it happens a third time, she may no longer be intimate with this husband. This is only the case when there’s no other cause to which the bleeding can be attributed but if they began intimacy near the start of her period, then we attribute it to her cycle. Similarly, if the woman had a wound, we attribute the blood to her wound. However, if the blood from the wound is a different color than the blood she sees during intimacy, then it can’t be attributed to her injury. If a woman says that she has a wound in her uterus that’s bleeding, her word is accepted and she remains permitted to her husband even though her uterus may bleed during intimacy.