Back pain after medical abortion may be caused by uterine contraction, pelvic inflammatory disease and other reasons. 1. Uterine contraction: The uterus will contract after medical abortion to promote the uterus to return to its original size and reduce bleeding. Uterine contraction will cause pain, usually paroxysmal, lasting about 3 to 4 days. 2. Pelvic inflammatory disease: If the symptoms of back pain after medical abortion continue to be unable to relieve, accompanied by purulent secretions, indicating the existence of pelvic infection and other conditions, at this time, if the ultrasound examination, will show that there is fluid in the pelvis and other conditions, the need to fight infection as soon as possible treatment. After the medical abortion, you need to consult a doctor to determine whether the pregnancy tissue is sufficiently discharged, and if the back pain continues to be unrelieved, you need to consult a doctor in a timely manner to ensure your health.