When blood is exposed to oxygen, it becomes oxidized and turns dark brown or blackish, similar to the color of coffee grounds. Black period blood and vaginal discharge isn't always a cause for concern. It commonly occurs at different times throughout a cycle, particularly toward the beginning of a period.
What does black period blood mean? Seeing black period blood can be alarming, but like brown blood, it's usually just old blood that's lingered in your body too long. This is most likely to happen during low flow days at the start or end of your period.
Deoxygenated blood is darker due to the difference in shape of the red blood cell when oxygen binds to haemoglobin in the blood cell (oxygenated) versus does not bind to it (deoxygenated).
Pelvic inflammatory disease (PID) or other infection
Black discharge may mean that older blood is leaving the uterus or vaginal canal. Heavy vaginal discharge of any color with a foul odor is also a symptom of these infections.
Black discharge can be an early sign of pregnancy. It may be caused by implantation bleeding or mild bleeding as a result of the fertilized egg attaching itself to the wall of the uterus. If you suspect you are pregnant, wait until the day of your missed period, or 1-2 days later before taking a home pregnancy test.
Endometriosis can cause black discharge if there's endometrial tissue causing a blockage within your vaginal cavity. Black discharge can also appear from endometrial tissue that's trapped but still produces blood.
The uterine lining darkens the longer it takes to leave the body. Period blood clots are normal on the heaviest days of your period and can appear deep red or almost dark black as well.
So it essential for people to learn what is normal for them. Healthy period blood typically varies from bright red to dark brown or black. Blood or discharge that is orange or grey may indicate an infection. Women who experience bleeding during pregnancy should see a doctor or obstetrician for an evaluation.
Good news: Dark red or brown period blood is typically nothing to be concerned about. “The primary reason that period blood could be brown is because it's old blood,” said Dr. Cummings. It usually happens at the beginning or the end of your period, when your flow is lighter.
Dark red blood: Dark red blood is simply blood that has been in the vagina for longer. It can even be seen with blood clots. Clotting is also considered normal unless the clots are larger than the size of quarters. Brown or black blood: These are color variations seen in blood that has taken longer to exit the vagina.
Venous bleeding
As the blood is coming from a vein, it is dark red. This is because it does not contain as much oxygen. Also, because veins are not under direct pressure, the blood flows steadily but comes out less forcefully than it does with arterial bleeding.
The colors of arterial and venous blood are different. Oxygenated (arterial) blood is bright red, while dexoygenated (venous) blood is dark reddish-purple.
Black or Brown Blood: Although black or brown blood may appear scary, it is not always a cause for concern. This tint might be mistaken for coffee grounds. Oxidized blood, which has had time to oxidize and change color, is generally black or brown.
Lochia can last from four to six weeks. There are three stages to lochia with characteristic color changes. The vaginal discharge between day 1 to day 3 after delivery is dark red. Between day 4 to day 10, the discharge is pinkish or brown, but it may change color to black if the flow is particularly slow.
Blood may look black if it sat in the uterus or vagina for a while. This can happen at the beginning or end of a period or could be related to a blockage. Very dark, heavy bleeding that looks gritty or has a lot of clumps could be a sign of a miscarriage or another condition (3).
Seeing different shades of red, brown, and even black blood during your period is typically normal and nothing to worry about. Blood contains hemoglobin and iron, a mineral that oxidizes when it comes into contact with air. When this occurs, it causes blood to become darker.
On the ovaries endometriosis can form “chocolate cysts” which are full of old blood which has a dark brown colour. The most favoured theory at the moment is that this occurs from blood going backwards through the tubes into the pelvis at the time of a period.
If you have endometriosis, you may experience irregular menstrual periods or bleeding between periods. Bleeding may be light, which is also referred to as “spotting.” However, bleeding could be heavy and look like a menstrual period even when it's not that time of the month.
The typical appearance of endometriosis is described as a superficial “powder-burn” or “gunshot” lesion that is black, dark-brown, or blue, but subtle lesions which are red or clear, small, cysts with hemorrhage or white areas of fibrosis may also be endometriosis (1).
Black period blood is blood that takes extra time to leave the uterus, becoming oxidized along the way. When blood is exposed to oxygen, it becomes oxidized and turns dark brown or blackish, similar to the color of coffee grounds.
Blood is always red. Blood that has been oxygenated (mostly flowing through the arteries) is bright red and blood that has lost its oxygen (mostly flowing through the veins) is dark red. Anyone who has donated blood or had their blood drawn by a nurse can attest that deoxygenated blood is dark red and not blue.
What color is blood? There's no need to build up the suspense: Blood is red. It might vary from a bright cherry red to a dark brick red, but it's always red.
The oxygenated blood means the blood that is rich in oxygen with very less carbon dioxide. The deoxygenated blood means the blood which is received to the heart and has greater concentration of carbon dioxide as compared to oxygen.