An anal fissure is a small tear in the thin, moist tissue mucosa that lines the anus. An anal fissure may occur when you pass hard or large stools during a bowel movement. Anal fissures typically cause pain and bleeding with bowel movements. You also may experience spasms in the ring of muscle at the end of your anus anal sphincter. Anal fissures are very common in young infants but can affect people of any age.
Anal Fissure: Symptoms, Causes, Diagnosis, and Treatment
An anal fissure is a break or tear in the skin of the anal canal. Anal fissures may be noticed by bright red anal bleeding on toilet paper and undergarments, or sometimes in the toilet. If acute they are painful after defecation,  but with chronic fissures, pain intensity often reduces. Anal fissures usually extend from the anal opening and are usually located posteriorly in the midline, probably because of the relatively unsupported nature and poor perfusion of the anal wall in that location.
Anal Fissure: A Common Cause of Anal Pain
The anal canal is a short tube surrounded by muscle at the end of your rectum. The rectum is the bottom section of your colon large intestine. An anal fissure also called fissure-in-ano is a small rip or tear in the lining of the anal canal. Fissures are common, but are often confused with other anal conditions, such as hemorrhoids.
A patient presents with severe anal pain, lasting hours after each bowel movement. She notices some intermittent bleeding with defecation. She comes to the office with the presumed diagnosis of hemorrhoids. Are her symptoms consistent with hemorrhoidal disease, or does she have another disorder? Benign anorectal disorders are common and increasing in incidence.