What Causes Abnormal Vaginal Bleeding?
This is likely normal...
Detailed Answer:
Thank you for the question.
In the setting of regular cycles, it is not so unusual to still have periods at age 55. If there was ANY irregularity to the cycle or bleeding unrelated to the cycle, then you need evaluation with an ultrasound AND endometrial biopsy to rule out pre-cancerous changes.
With regard to the appearance of the blood, this is also likely normal. With the smaller amount of bleeding, I am presuming, it makes its way out much slower and this is associated with the darker blood. It might even appear brownish towards the end of the period.
You should still be getting annual exams. Make sure that you also discuss this with your doctor and make sure that they (who know you much better including your past medical history) believe that this also sounds normal.
I hope that this helps!
Dr. Tim