Dam Makah - Blood from a wound
Dam Makkah is blood that comes from a wound or trauma and therefore does not cause a woman to become Nidah. Blood that originates from the uterus is the kind of bleeding that causes one to become Nidah. (A wound in the uterus is a complex situation which will not be addressed here.) At times, Dam Makah may interfere with a successful Hefsek Taharah and achieving clean Bedikot. It may even be noticed on underwear, or tissues used in the bathroom (please note that there is no halachic obligation to inspect used tissues, this only gives rise to issues and should be avoided).
Wounds can be found on the cervix, the vaginal canal, or on the labia. The wound may not necessarily be considered a "medical wound", or pathological finding, or be of any health concern at all. In fact, many wounds are only considered wounds halachically and would not be considered to be a wound, medically. Many of these wounds do not cause any pain at all.
Some common sources of wounds are an ectropion, polyps, the stitch site after delivery of a baby and a prolapsed uterus. Urinary infections are sometimes accompanied by bleeding from the bladder, which would not be Dam Nidah. Other causes of a Makah-wound are excessive Bedikot, Bedikot done in a rough manner, washing of the vaginal canal, and waxing.
During the different stages of a woman's reproductive cycle, she may be more prone to wounds. Nursing mothers, as well as post-menopausal women, tend to have a drier, than usual, vaginal canal which can lead to bleeding when touched. During pregnancy, the vaginal canal and surrounding area may be engorged with blood making these areas more prone to bleeding on contact. During the post-partum stage, the vaginal canal and/or cervix may also bleed when touched until complete healing takes place. Usually the bleeding caused by these situations would be paskened - halachically ruled -as Dam Makah by the Rav.
Various birth control methods (when permitted under Rabbinical ruling) can affect the integrity of the vaginal canal and cervix, causing these areas to bleed when touched. This too could be considered as Dam Makah, by the rav. Again, the rav should be consulted.
Many gynecological procedures can cause bleeding of the cervix, or vaginal canal, due to trauma caused by medical instruments. This bleeding would usually be classified as Dam Makah and would not cause a Nidah status.
These are some examples of Dam Makah that may occur that could be classified as non Nidah bleeding/staining. However, it is important to note that any sighting of blood, which one suspects is not uterine bleeding, must be presented, along with all relevant information, to a Rav for halachic ruling. The Rav will use the concept of "Teliyah" (attributing to something other than the uterus) to attribute the bleeding to a wound, if such is the case. Many times the Rav will require additional information provided by a physical exam. A trained and certified Bodeket can perform this exam to verify the source of any bleeding. She will then provide a report to the Rav who will pasken (provide a halachic determination) whether or not the blood is Dam Makah.