If you notice a small amount of bright red blood that is not mixed with your stool, and particularly if it follows bouts of constipation or straining to pass your stool, then the odds are that it is the result of hemorrhoids (or, less likely, an anal fissure). However, it is impossible to rule-out a more ominous explanation through an Internet-based discussion, or through a CBC, or even through a DRE that did not reveal any apparent positive findings.

Given that you are entering the age range where colorectal cancer begins to become more common, I would recommend that you undergo an endoscopy. (The "gold standard" evaluation would be a colonoscopy.) If you were referred to me with the same complaints, I would perform a colonoscopy to rule-out colorectal cancer and, assuming no cancer or advanced adenomatous polyps were identified, to definitively identify the source of your rectal bleeding.

Sincerely,

Robert A. Wascher, MD, FACS