Uterine fibroids. Cutaway computer illustration showing fibroids (white, round) in a uterus (womb, centre), with the ovaries (beige, top left and right), oviducts (tubes, top left and right) and vagina (bottom) also shown. A fibroid is a fibrous benign (non-cancerous) tumour originating from muscular tissue. Most do not require treatment, but some can cause bleeding, pain and other disorders. Large fibroids may need to be surgically removed. Shown here are: pedunculated fibroid (stalked, upper centre), intracavitary fibroid (centre-left), submucosal fibroid (far centre-left), subserosal fibroid (upper centre-right), intramural fibroid (centre-right).