Normal menstrual bleeding occurs every 21 to 35 days, lasts two to six days and does not occur in the middle of the menstrual cycle. Bleeding that occurs for prolonged periods of time or on and off all month is called menorrhagia. Abnormal menstrual bleeding is considered dysfunctional uterine bleeding, or DUB. Dysfunctional uterine bleeding occurs more frequently when women first start having menstrual cycles and at the end of the menstrual reproductive cycle.
Anovulation
Ovulation is the release of an egg each month. Anovulation is lack of ovulation and is most often the cause of DUB, according to Louisiana State University Health Sciences Center, or LSUHSC. In a normal menstrual cycle, estrogen rises until an egg releases from a follicle. The leftover shell of the follicle produces progesterone, which maintains the uterine lining for a potential embryo. If no pregnancy occurs, progesterone levels drop, and the menstrual lining is shed. Continuously high estrogen levels stimulate endometrial lining growth until parts begin to break down and bleed. Since different areas are being stimulated and breaking down continuously, constant bleeding occurs.
Endometrial Cancer
Endometrial cancer must be ruled out in every case of DUB, LSUHSC reports. Around 75 percent of cases of endometrial cancer don't occur until after menopause. Obesity, diabetes, a history of polycystic ovary disease, never having had children, and later-than-normal onset of menopause all increase the chances of endometrial cancer. A family or personal history of ovarian cancer or breast cancer, particularly if the woman took tamoxifen, also increases the risk of endometrial cancer.
Fibroids
Fibroids, which are common benign growths either inside or outside the uterine walls, often cause heavy bleeding along with bleeding or spotting between periods. Fibroids can be seen on pelvic ultrasound exams. Fibroids occur more frequently in black women and those with a family history of fibroids. Obesity may also increase the risk of fibroids, MayoClinic.com reports. Fibroids may be surgically removed if they're causing excessive bleeding. Pelvic pain, constipation, difficulty urinating and back or leg pain may also occur in women with fibroids.
Polyps
Polyps, which are fleshy growths inside the uterus, may cause frequent spotting and constant bleeding. Rarely, polyps may grow to the size of an orange. Frederick R. Jelovsek, MD, of Women's Health Resource reports that polyps may be diagnosed through hysteroscopy -- looking into the uterus with a lighted scope -- or with a sonohysterogram, a procedure involving dye being injected into the uterus and then tracked via X-ray. Surgical removal or medical treatment with drugs that decrease estrogen levels and shrink polyps help control excessive bleeding. Polyps occur more frequently up to menopause, and then they shrink. Between 10 and 24 percent of women undergoing endometrial biopsy or hysterectomy are found to have polyps, according to MDGuidelines.
