What causes menstrual blood to be dark brown?

　　"Aunt's blood" usually refers to menstrual blood. Generally, the main reasons for menstrual blood appearing blackish brown include light menstrual flow and blood retention, abdominal chilling, endometritis, polycystic ovary syndrome, intrauterine adhesions, etc. If discomfort symptoms occur, it is recommended to seek timely diagnosis and treatment at a regular hospital. Detailed analysis is as follows:

　　1. Light Menstrual Flow and Blood Retention

　　At the beginning or end of the menstrual period, the flow is relatively light, and the blood remains in the uterine cavity for a longer time. Hemoglobin undergoes oxidation, causing the color to turn blackish brown. It is important to maintain a regular lifestyle, avoid excessive fatigue, and walking appropriately during menstruation can help discharge menstrual blood. Drinking more warm water also helps improve blood retention and alleviate abnormal coloration.

　　2. Abdominal Chilling

　　Improper abdominal warmth during menstruation allows cold to invade, causing pelvic blood vessels to constrict, hindering menstrual blood discharge. The retained blood oxidizes and turns blackish brown, possibly accompanied by dysmenorrhea. Strengthen abdominal warmth, use a hot water bag to apply heat to the abdomen during menstruation, drink warm brown sugar ginger tea to dispel cold, avoid consuming cold foods, reduce blood vessel constriction, and promote smooth menstrual blood discharge.

　　3. Endometritis

　　Bacterial infection causes inflammation of the endometrium. Inflammatory stimulation leads to congestion and edema of the endometrium. Menstrual blood mixes with inflammatory secretions and is obstructed from discharging, causing oxidation and turning the color blackish brown. It is often accompanied by lower abdominal heaviness and increased vaginal discharge. Under a doctor's guidance, medications such as metronidazole tablets, levofloxacin hydrochloride capsules, and cefixime dispersible tablets can be taken to control the infection.

　　4. Polycystic Ovary Syndrome

　　Endocrine disorders lead to abnormal ovulation by the ovaries, insufficient estrogen levels, uneven thickening of the endometrium, less bleeding and slow discharge during shedding, oxidation of menstrual blood turning it blackish brown, accompanied by prolonged menstrual cycles and hirsutism. Under a doctor's guidance, medications such as drospirenone ethinylestradiol tablets, ethinylestradiol cyproterone tablets, and dydrogesterone tablets can be used to regulate hormone levels.

　　5. Intrauterine Adhesions

　　Multiple intrauterine procedures cause endometrial damage, resulting in partial or complete adhesion of the uterine cavity. Menstrual blood discharge is hindered, retained blood oxidizes and turns blackish brown, accompanied by significantly reduced menstrual flow and dysmenorrhea. Mild adhesions can be treated under a doctor's guidance with medications such as estradiol valerate tablets, progesterone capsules, and aspirin enteric-coated tablets to promote endometrial repair. Severe adhesions require hysteroscopic adhesion lysis to restore the normal shape of the uterine cavity and improve menstrual blood discharge.

　　In daily life, attention should be paid to keeping warm during menstruation to avoid abdominal chilling; maintain a regular lifestyle and avoid staying up late and excessive fatigue; maintain personal hygiene and change sanitary products frequently during menstruation; and undergo regular gynecological examinations to promptly detect and treat gynecological diseases, maintaining reproductive health.