Uterine fibroids are depending on the size, shape and location may occur inside the uterus, on its outer surface or within the walls. Fibroids can range in size from pea-sized growths to large melon sized growths. As fibroids grow they can disturb the inside as well as the outside of the uterus and can completely fill the pelvis and abdomen. Fibroids can occur singly or in multiples of varying sizes. Growth of the fibroid is unpredictable. They may remain very small for a long time, suddenly grow rapidly, or grow slowly over a number of years.