Abnormal bleeding between periods can occur at any point in a woman’s reproductive years. This bleeding can be caused by abnormalities in the uterus, ovaries, vagina and brain. Many of these abnormalities are caused by hormonal imbalances or may cause hormonal imbalances. Depending on the underlying cause, the bleeding can be short lived or prolonged.

Uterine Growths

Uterine fibroids and uterine polyps often cause bleeding in between periods 12. Uterine fibroids are abnormal uterine growths that are estrogen sensitive 1. According to MayoClinic.com, these growths occur in 3 of 4 women at some point in their lifetime 123. Uterine fibroids can grow within the muscles in the uterine wall, bulge into the uterine cavity, or hang from the uterine lining 1. Most women have no symptoms, but some women may experience heavy menstrual bleeding, prolonged menstrual bleeding, spotting, frequent urination, constipation, backache and arm ache. Uterine polyps are benign uterine growths that protrude into the uterine cavity 2. Uterine polyps grow from the uterine lining by a thin stalk and can expand from a few millimeters in size to the size of a golf ball or larger 2. According to MayoClinic.com, these growths occur in women in their 40s and 50s, although they can occur in younger women 123.

Ovarian Growths

Ovarian cysts are one of the most common causes of bleeding in between periods due to the ovary 3. There are two types of ovarian cysts--follicular cysts and corpus luteum cysts 3. Follicular cysts form when the luteinizing hormone, or LH, doesn’t surge during ovulation to cause the follicle within the ovary to release it. These cysts are harmless and usually go away after a few cycles. The follicle within the ovary becomes a corpus luteum after the LH surge takes place and the egg is released. Sometimes the follicle opening seals off and fluid begins to accumulate inside of the cyst, which causes it to become a cyst. These cysts may grow several inches in diameter and can bleed or cause the ovary to twist. Symptoms are pelvic pain, irregular menstrual cycle, pain during bowel movements or pressure in bowels, heaviness in abdomen, bleeding in between period, and nausea.

Reproductive Diseases

Polycystic ovary syndrome is a condition that causes the ovary to retain several cysts 5. During menstruation, the level of luteinizing hormone increases and then surges around the time of ovulation. Women with PCOS have a raised LH level even before ovulation begins; this causes an interruption or lack of ovulation as well as an irregular menstrual cycle. Researchers are not certain what causes this condition, but they speculate that it may be hereditary. Symptoms are bloating, irregular bleeding, infertility, facial hair, enlarged ovaries and diabetes type 2. Another reproductive disease that causes abnormal bleeding between menstrual periods is endometriosis 4. This condition causes the uterine tissue to grow outside of the uterus. Areas of endometriosis can be found on the bladder, abdomen, ovaries, colon and uterus 4.

Birth Control Side Effects

Abnormal menstrual bleeding between menstrual cycles can be caused by medications used during fertility treatments or for birth control. Birth control pills are prescribed both to stop ovulation by leveling out the hormones estrogen and progesterone or by correcting irregular hormone levels. Birth control pills may cause abnormal bleeding within the first four months of use, and for some women it may even occur after long term use.

Warnings

Heavy bleeding with abdominal pain should be investigated by a physician immediately. Women who may be pregnant should seek emergency care.