Causes of heavy, painful periods include uterine fibroids, nonhormonal intrauterine devices, adenomyosis and pelvic inflammatory disease, reports WebMD. Severe menstrual cramps accompanied by heavy bleeding may be a sign of endometriosis, according to MedicineNet.
Fibroids are noncancerous tumors that develop in the uterus of some women during their child-bearing years, reports Mayo Clinic. Uterine fibroids increase the amount of bleeding and make menstrual pain more severe, according to Everyday Health. The pain occurs as a result of increased contraction or cramping as the uterus expels the huge blood clots formed due to heavy bleeding.
Copper intrauterine devices often make periods heavier and more painful during the first few months after insertion, reports Everyday Health.
Endometriosis is a condition in which the uterine lining grows on other structures, such as the pelvic floor and the fallopian tubes, according to Everyday Health. It often causes heavy bleeding and excruciating pelvic pain. Adenomyosis is a condition in which the uterine lining embeds itself deep into the uterine muscle. This causes a lot of pain and heavy bleeding, reports Mayo Clinic.
Pelvic inflammatory disease is a reproductive tract infection usually caused by an untreated sexually transmitted disease, explains Everyday Health. These sexually transmitted diseases often leave adhesions and scar tissue in the pelvic region. Hormones released during menstruation influence the uterus as well as the adhesions and scar tissue, causing increased pain, inflammation and bleeding.