A 36-year female complaints of abdominal pain & constipation since 5 years. She has on & off rectal bleed when she tries to defecate forcefully. The most probable diagnosis is:

The findings are consistent with irritable bowel syndrome. Crohn's disease would typically have perianal fistulae while ulcerative colitis has periods of acute disease and quiescent periods: the acute periods are severe and may lead to significant impairement.