A rectal fissure, also called an anal fissure, is simply a tear that develops within the lining of the anus, which is the lower part of the rectum. Though this condition can afflict people of all ages, it is especially common in babies. When an adult has this condition, it is usually due to chronic diarrhea, hard stools or a condition that causes insufficient blood flow to the anal region. It can also occur due to excess tension within the sphincter muscles. The primary symptoms of a rectal fissure include pain and bleeding during bowel movements. While many such tears can close without medical treatment, chronic and slow-healing fissures can be treated with Botox injections, prescription ointments and minor surgical procedures.