The cause of chronic left flank pain can range from easy-to-treat menstrual pains to something much more serious, such as colon cancer. Being able to recognize the symptom and seek medical advice is essential for early diagnosis and treatment of the problem before it escalates. In women, the most common reasons for chronic left flank pain are related to ovulation. Mid-cycle pain, also called Mittleschmerz, refers to the pain during ovulation when then the eggs are released from the ovary. Polycystic ovarian syndrome, a common disorder in women, can cause pain in the lower abdomen on the left side and tends to be reoccurring. If a cyst on the ovaries becomes twisted or ruptured, it can be very painful on both sides of the abdomen. Ectopic pregnancy, a miscarriage, pelvic inflammatory disease, and endometritis can all also cause left flank pain. Reproductive Disorders and Conditions in Men Testicular disorders and spermatic cord disorders can cause men to experience reoccurring pain in the left flank. The sexually transmitted disease gonorrhea can also cause pain in the lower left abdominal area—especially for men. Kidney Disorders and Conditions Kidney and urinary stones can be a very painful and mimic the pain of an appendicitis attack if on the right side of the body. However, they also occur on the left side of the body and can cause chronic discomfort and pain. An infection of the kidneys, or glomerulonephritis, can be extremely painful if not found in its early stages. Kidney cysts or tumors can also be present and cause discomfort or pain to the left flank of the body. Colon Disorders and Conditions Constipation is very common and can tend to cause chronic left flank pain or discomfort. Splenic flexure syndrome is when gas gets trapped in the left part of the transverse colon and can cause pain to the left side of the abdomen. Cancer in the colon can also cause flank pain. Inflammatory bowel disease, including Crohn’s disease or ulcerative colitis, can cause irritation that will cause pain or discomfort to the colon and cause pain on the sides of the body. Other colon-related disorders and conditions that may cause left flank pain includes diverticulitis, ischemic or microscopic colitis, and diverticulosis. Other Disorders and Conditions Surprisingly, appendicitis can cause left flank pain. Although the normal symptom of appendicitis is right flank pain, in rare cases left flank pain results instead. The large intestines can become infected or twisted, causing pain on the left side. An enlarged or infected spleen can also be to blame for left flank pain. Source
