A few questions regarding anal fissures: can they casue constipation and smaller, harder stools? can they cause a constant pain in the rectal area? can they cause mild abdominal pain? can it still be considered a fissure even if there isn't any blood?

Anal fissures are caused by passage of bulky/hard or too rapid stooling. They are the result of not the cause of constipation, unless of course you try to withhold stools to avoid a movement & they dry/bulk as a result. Fissures can narrow the outlet after healing. The cycle can be avoided by emptying more often, adding fiber & fluids to the diet. A fissure bleads/a scar does not.