What Are The Tests That Can Be Done For Blood In Stool?

i have ben having a problem with blood in stool...this has been going on since about may...the blood is not noticable until after bowel movement...it is a darker red...there is no pain during movement, nor before or after...i've had a problem with diarrhea for years...live on imodium...i've lost some weight...i've not told my wife any of this yet...she has her own problems with her lungs and i will tell her when she gets her answers...i don't want to go through a colonoscopy..so is there any other tests that could be done...