Uterine fibroids are common, non-cancerous tumors that form in a woman's uterus. Fibroids develop on the uterine wall or attach themselves to it. They can be quite small or grow to several pounds. They can grow alone or in clusters and can result in pelvic pain, frequent urination, and bleeding.
Fibroids that are in the uterine wall are known as intramural fibroids. Those that grow outside of the uterus are called subserosal, while those that develop in the uterus itself are sub-mucous fibroids. These are the type that can precipitate heavy bleeding and they don't have to be that large to be a serious problem. They can make a woman bleed heavily during menstruation and in between periods.
Uterine bleeding is the symptom that causes most women to seek treatment for fibroids. The fibroids can cause the uterine cavity to get bigger, which forms a larger area that can then be subject to menstrual bleeding. Pressure from fibroids also can result in bleeding. Abnormal bleeding from the uterus can be caused by other conditions---fibroids alone should not be assumed to be the cause until a thorough exam has been done. The dangers to a woman from fibroid bleeding include physical and emotional distress as well as dizziness and fainting caused by the loss of blood. Anemia can be another side effect of this bleeding.
The exact reasons fibroids sometimes cause heavy bleeding is unknown, but one theory proposes that when the uterine lining is shed during a woman's period the uterus is subject to bleeding. This bleeding can be stopped by normal blood clotting or by the uterus, since it is a muscle, contracting and squeezing the bleeding vessels. This squeezing results in the cramps that women experience during a period. The thought is that fibroids do not allow this muscle contraction to function properly, leaving bleeding blood vessels open longer than they normally would be. Fibroids are also believed to produce proteins that make blood vessels near them grow and expand, meaning even more blood can be lost during menstruation.
Your doctor will want to know your medical history before doing a physical examination to determine what to do if you have fibroid bleeding. Ultrasound tests on the pelvis can locate fibroids and allow the doctor to identify how large they are. A tissue sample taken from the uterus itself, called an endometrial biopsy, can be useful in identifying fibroids. A hysteroscopy employs a tiny camera on a tube to get a view of the uterus and a hysterosalpingography is a test in which a dye is injected into the uterus, allowing X-rays of the region to show whatever may be present. A laparoscopy is a surgical method that can remove fibroids using a fiberoptic camera to guide the surgeon's moves.
A woman needs to seek a medical opinion if she experiences bleeding between periods or unusually heavy menstrual bleeding, the type that soaks through as many as three pads in an hour's time. Fibroids occur in a quarter of all women and are the most common cause of hysterectomies. Statistics show that 20% of women over 35 years old have uterine fibroids.