A bulky uterus, a condition that is also called adenomyosis, occurs when the endometrial lining grows into the muscle of the uterus. Women who have had children and are older than 30 are more likely to develop a bulky uterus. Although the condition is not the same as endometriosis, it does commonly affect women who also suffer from that condition, in which the endometrial lining grows in parts of the body other than the uterus. Some women have no symptoms, but others might experience heavy menstrual bleeding and cramps.

Several conditions might lead to a bulky uterus or adenomyosis, although the exact cause remains unknown. The condition can occur if the uterus becomes inflamed, such as immediately after a woman gives birth. It might also occur after a woman has had a Cesarean section, because the incision into the uterus allows the endometrial cells to invade the muscular walls of the uterus and to begin growing there. Another possible cause of a bulky uterus is endometrial cells that formed in the uterine muscles when the woman was a fetus.

In many cases, women who have a bulky uterus do not even know they have the condition. Very heavy bleeding during menstruation can be a sign of adenomyosis, as can passing blood clots during the period or bleeding between periods. Some women might have sharp cramps that grow worse as they get older, or they might experience pain during sex.

The uterus might swell to triple its usual size because of adenomyosis. Even if a woman has no other symptoms, she might notice that her abdomen is swollen or feels tender. A doctor might be able to diagnosis the condition by feeling the pelvic area. Other ways to diagnose a bulky uterus include ultrasound imaging or a magnetic resonance imaging (MRI) test, which will determine whether the woman has adenomyosis or a more serious condition, such as a tumor.

Usually, a bulky uterus will shrink back to normal after a woman goes through menopause, because estrogen plays a key role in causing the condition. Depending on how severe her symptoms are, a woman might need to take medication, such as anti-inflammatory pills or pain medicines, to cope with adenomyosis. Some women might use birth control to reduce pain and bleeding during periods. Occasionally, a hysterectomy might be necessary, especially if the woman is in a great deal of pain, doesn't plan on having more children and is still several years away from menopause.