Why is Menstrual Blood Sometimes Dark?
Menstrual fluid tends to be brightest red when your flow is heaviest. As the menstrual flow slows down, it takes longer to exit the vagina, as a result, the blood component loses its oxygenated red hue and becomes darker red, then brown and at times practically black.
Arterial and venous blood, proteolytic enzymes, remnants of endometrial glands, stromal cells (connective tissue), leukocytes and red blood cells are present in menstrual fluid.
Many women have dark brown (slow menstrual blood) before their period and some have the darker light flow as the period tappers off. The color of menstrual blood can vary month to month. A darker fluid most often reflects that menstrual fluid is slowly leaving the body.
Understanding Menstrual Blood Clots
Clots are the natural result of the body functioning well. They are a natural way of controlling bleeding. When menstrual bleeding is heavy, clotting tends to occur. Experiencing menstrual clots can be upsetting. If the clots are large they can be painful and cause cramping as they pass through the cervix: the very top of the vagina.
The following is a brief explanation as to why menstrual clots (often large clots) are formed. All blood contains a clotting factor. To enable menstrual blood to flow freely from the uterus and leave the body without clotting, the uterus produces an anti-clotting agent: plasmin. However, when menstrual loss is heavy, the anti-clotting agent may not be adequate for the menstrual period and the blood is likely to form clots. Additionally, if menstrual blood accumulates faster than the body’s ability to transfer it out of the uterus, clots can result.
More specifically . . .
Fibrin is a protein that creates a blood clot by forming a network of trapped red blood cells and platelets.
Plasmin is an enzyme that digests or breaks down fibrin. In general, menstrual blood clots form when there is an slight imbalance between fibrin (builds) and plasmin (breakdown).
Menstrual Cramps
Menstrual cramps often result when the endometrial and myometrial tissues; the uterine lining and muscle secrete excess series 2 prostaglandins. Prostaglandins are hormone type substances that can promote inflammation including pain, swelling and tenderness. Prostaglandin stimulates the activity of myometrial cells.
A few days prior to or upon menstruation, prostaglandin release helps start the contractions that are necessary to shed the temporary layer of the endometrium. Excess prostaglandin can create mild to extreme discomfort such as spasm/cramps in the uterine muscle (myometrium), back ache, sweating, chills, nausea, constipation or diarrhea and feeling faint. Women with menstrual cramps have prostaglandin blood levels that are significantly higher than women who do not experience cramps.
Many women can lessen the intensity of menstrual cramps by taking a daily ibuprofen (over the counter) each day pre-menstrually. . . and during the onset/start of their period. Ibuprofen helps lessen the production of the prostaglandin hormone that contributes to menstrual cramps.
Keep in mind if experiencing severe menstrual cramps, and your prostaglandin levels are very high, over the counter ibuprofen probably will not be potent enough to relieve the severe cramping. A prescription ibuprofen would bring better relief.
Heavy or Irregular Menstrual Bleeding
The amount of menstrual fluid is determined by the size of the uterus and the hormonally induced endometrial thickness. During the follicular phase (about the first 2 weeks) of the menstrual cycle, estrogen gradually builds up the uterine lining (endometrium). Estrogen causes the proliferation (growth) of endometrial stroma cells (connective tissue), epithelial cells (tissue), glands, vascular cells and the number of gap junctions. Estrogen increases myometrial excitability and stimulates uterine contractility.
Progesterone is the hormone that promotes uterine relaxation. During the secretory phase (last 2 weeks) of the menstrual cycle, progesterone stops *growth of the endometrial tissue. Progesterone holds down the excessive tissue growth effects of estrogen. Heavy or irregular bleeding often occurs because estrogen dominance causes the temporary layer of the endometrium to overgrow. To much endometrial tissue builds up and then breaks down in a disorderly way. Low levels of progesterone cannot counteract the excess estrogen.
Cortisol is a hormone released due to stress. Cortisol impairs or diminishes progesterone activity; for many women low levels of progesterone contributes to excess menstrual bleeding and heavy cramping.
To a certain degree, stress can contribute to endometrial tissue buildup because stress drains the body of hormone balancing and healing nutrients. Stress increases cortisol levels. Cortisol impairs progesterone activity, by blocking or competing for progesterone receptors. Low progesterone contributes to estrogen dominance. This unbalance of excess estrogen contributes to proliferation (growth) of the uterine lining (endometrium); this tissue over growth often contributes to heavy or irregular bleeding. Stress is not the primary factor, but it can be a contributing factor.
A bit more about progesterone
*Progesterone decreases the biological activity of estradiol (estrogen) on the endometrium by decreasing the concentration of estradiol receptors, increasing the activity of 17 B-hydroxysteriod dehydrogenase type II, the enzyme responsible for the conversion of estradiol to estrone, and by increasing the activity of estrone sulfotransferase.
The primary role of progesterone is to support egg implantation and sustain pregnancy. Progesterone supports pregnancy by inhibiting uterine contractions and by supressing the immune systems response to the developing embryo as a foreign body.
Just before ovulation progesterone secretion is 2 - 3 mg per day. After ovulation progesterone secretion is 20 - 25 mg per day, one week post ovulation 30 mg per day and during the third trimester of pregnancy 300 - 400 mg per day.