What causes pain in the lower abdomen?

Left and right abdominal pain, more common in pelvic inflammatory disease or chronic pelvic pain. Female acute pelvic inflammatory disease, not timely and effective treatment, or treatment is not complete, into chronic pelvic inflammatory disease, that is, chronic pelvic pain, manifested as abdominal pain. Female pelvic middle is the uterus, both sides of the appendix (fallopian tubes and ovaries. Uterine front is the rectum behind the bladder. Left and right lower abdominal pain, the most common cause is appendicitis, including pyosalpinx, hydrops, suppurative salpingitis, periovaritis, ovarian abscess, cyst, connective tissue inflammation, etc. Occasionally there are intestinal diseases, such as colitis, tumors, etc. Occasionally ureteral diseases, such as ureteral stones, obstruction, tumors, etc.