They may be as small as a seed or grow so big that they form a bulky mass that can distort and enlarge the uterus, according to the Mayo Clinic. Fibroids generally grow slowly, at a rate of around 9 percent, on average, over a six-month period during a woman's reproductive years, Lim said. It took up the woman's entire abdominal and pelvic cavity, extending up to the very bottom of her breastbone, Lim said. Interestingly, the woman did not have any bowel difficulties, such as constipation , and she could eat well despite the fibroid's size large fibroids may cause abdominal discomfort if they put pressure on surrounding organs , Lim said. About 70 percent of women develop these growths by the time they reach age 50, Lim said. Among patients who survived the procedure, the largest fibroid ever removed weighed lbs. The surgery to remove such a massive tumor was challenging, the report said. In most cases, fibroids don't cause symptoms, the Cleveland Clinic says, but symptoms such as excessive bleeding during menstruation, pain during intercourse, frequent urination or a feeling of fullness in the lower abdomen can occur. The woman also experienced some shortness of breath, both when she moved and when she lay down, said Lim, who treated the woman.