Uterine sarcoma
Uterine sarcomas and fibroids are alike. Both have an increased uterine size. Abdominal pain and vaginal bleeding happen in both. It can be difficult to tell them apart. Unusual vaginal bleeding may be a sign of uterine sarcoma. Other signs of a uterine sarcoma can be pelvic pain, pressure, and unusual discharge.  If a uterus is larger than normal this could also be a sign.  There is no special test to detect a uterine sarcoma. A Pap smear is a screening test for cervical cancer and not designed to detect uterine sarcoma.