While black vaginal discharge is not typical for most women, its occasional appearance is rarely cause for alarm. In most cases, it is old blood left over from menstruation or implantation of an embryo. It may also signal a foreign object in the vagina, such as an old tampon or condom, a problem that is usually quickly remedied by a doctor removing the item. In some cases, though, black vaginal discharge is a sign of cervical cancer, which is why any abnormal vaginal discharge should be reported to a doctor unless the cause is immediately obvious.
One of the most common reasons for black vaginal discharge is that old blood was stuck in the cervix. In general, the darker the blood is, the longer it has been in the cervix, and it is normal for some blood from menstruation to take days or even weeks to make its way out of the vagina. If the menstrual period is late and the black vaginal discharge is present instead, it could be implantation bleeding. This occurs once an egg is fertilized, creating an embryo that implants in the uterine lining; this can draw blood that may be pink, brown or black, depending on how old it is. Once implantation has occurred, a home pregnancy test should be accurate.
Some women may have a foreign object in their vagina that they do not notice until they see black vaginal discharge. The item that is most commonly stuck in the vagina is a forgotten tampon, though condoms may also slip off and become hidden inside. When this is the case, the discharge is often accompanied by an unpleasant odor. Patients can try to remove the object on their own, but a doctor can also do the job. In most cases, there are no lasting consequences once the foreign object is removed, and the discharge should stop soon after removal.
Cervical cancer is a possible, though rare, cause of black vaginal discharge. This is because one of the main symptoms is abnormal vaginal bleeding, which describes bleeding after menopause and between menstrual periods in women of childbearing age. In many cases, the bleeding is accompanied by a foul odor, especially if the blood has been in the cervix for a while, which would be the reason it has turned black. Women should be aware that cervical cancer often has few — if any — symptoms, so while it is unlikely that this is the cause of black vaginal discharge, the issue should be checked out by a doctor.