Irregular bleeding between the menstrual periods

Metrorrhagia (metro = womb, -rrhagia = excessive flow) is uterine bleeding at irregular intervals, particularly between the expected menstrual periods. 

In some women, menstrual spotting between periods occurs as a normal and harmless part of ovulation. Some women experience acute mid-cycle abdominal pain around the time of ovulation. This may also occur at the same time as menstrual spotting. The term breakthrough bleeding or breakthrough spotting is usually used for women using hormonal contraceptives, such as oral contraceptives, in which it refers to bleeding or spotting between any expected withdrawal bleedings, or bleeding or spotting at any time if none is expected. Breakthrough bleeding is likely due to hormonal fluctuations. The body is programmed to make certain estrogen levels each day and the estrogen (and some additional hormones, such as FSH (follicle-stimulating hormone), LH (luteinizing hormone), and progesterone) are responsible for regulating endometrium shedding. Therefore, when new levels of hormones enter the body through oral contraceptives, the body is provided with two ways to receive estrogen. These excess estrogen levels can cause pre-period bleeding (bleeding through). This should be regulated in several months. 

Besides the aforementioned physiologic forms, metrorrhagia may also represent abnormal uterine bleeding and be a sign of an underlying disorder, such as hormone imbalance, endometriosis, uterine fibroids, uterine (endometrial) cancer, or endometrial polyps.

If the bleeding is repeated and heavy, it can cause significant iron-deficiency anemia.

Endometriosis

Endometriosis is a gynecological condition characterized by extra-uterine endometrial-like cells, which often proliferate and cause hematomas, menstrual pain, or other symptoms, in conjunction with hormonal changes.

The clinical symptoms of endometriosis include severe dysmenorrhea (painful menstruation), deep dyspareunia (pain with intercourse), chronic pelvic pain, ovulation-related pain, heavy menstrual bleeding and/or spotting between periods, and painful bowel and/or bladder symptoms that occur during or prior to menstruation.

Endometrial cancer

Endometrial cancer is the most common gynecological malignancy in developed countries. Approximately 90% of women with endometrial cancer have abnormal uterine bleeding as the only presenting complaint leading to the diagnosis of the disease. It has been suggested that screening of asymptomatic endometrial cancer by transvaginal ultrasound before the onset of clinical symptoms, i.e., postmenopausal bleeding, leads to an earlier diagnosis. 

Uterine fibroids

Uterine fibroids are benign tumours of the smooth muscle of the uterus. Common complications of uterine fibroids include irregular bleeding with symptoms of anaemia. Submucosal fibroids may also present with intermenstrual bleeding. This is especially prevalent with prolapsed (a condition where organs, fall down or slip out of place)submucous fibroids. Any woman with fibroids and intermenstrual bleeding must, however, have a pelvic examination and pap smear to make sure an obvious cervical cancer is ruled out.

Endometrial polyps

Endometrial polyps (EPs) are one of the most common gynecological conditions often diagnosed incidentally or associated with clinical symptoms such as infertility in reproductive age and abnormal vaginal bleeding both in premenopausal and postmenopausal women. The stroma of the polyp is composed of spindle cells and large blood vessels with thick walls which are very fragile and vulnerable to rupture.