Many anal and rectal problems involve abnormal structures and can be identified by a visual or manual examination. These include:

• Hemorrhoids and anorectal varices. Hemorrhoids are stretched, dilated veins in the walls of the anus and rectum. They may remain inside the anus or protrude. Hemorrhoids occur when pressure in the affected vein increases due to a variety of factors (e.g., straining during defecation, frequent heavy lifting, pregnancy). Anorectal varices are small, swollen veins located just under the inner mucosa layer in the anus and rectum. While they appear similar to hemorrhoids, anorectal varices are not directly related to them. They are the result of high blood pressure in the portal vein (portal hypertension).
  
  
• Obstruction and fecal impaction. Obstruction occurs when something blocks the stool and impedes defecation. Fecal impaction occurs when obstruction is caused by hardened stool in the colon or rectum. This occurs more frequently in older adults and pregnant women. Possible causes of other forms of obstruction include anal stenosis, dysfunction of the pelvic muscles, Crohn's disease, injury or inflammation following radiation therapy, infection and cancer.
  
  
• Anal fissure and ulcer. An anal fissure is a tear in the lining of the anus. If the fissure does not heal, it becomes an ulcer. Anal fissures cause spasms in the anal sphincter, which make healing difficult. They may be caused by a hard or large bowel movement or by sexual penetration of the anus.
  
  
• Anorectal fistula. An abnormal passageway between the anus or rectum and the skin around the anus or another organ, especially the vagina (rectovaginal fistula). While these may be birth defects, they are usually caused by an abscess. Congenital (birth defect) fistulas are more common in boys. Anorectal fistulas may develop after injury during childbirth, after radiation therapy or as a result of certain diseases (e.g., diverticulitis, Crohn's disease, tuberculosis, cancer).
  
  
• Rectal prolapse and rectocele. Rectal prolapse occurs when the rectum turns inside out and protrudes through the anus. In children, it may occur while they are straining to defecate, which is usually temporary and not serious. However, in adults, prolapse typically persists and worsens. In some cases, the entire rectum may prolapse (procidentia). In women, rectocele occurs when the rectum protrudes into the vagina. Rectal prolapse and rectocele in adults are generally believed to be caused by a loss of strength in the tissues that hold the rectum in place. This is more common with advancing age. Rectocele occurs as a result of damage after vaginal childbirth, the strains to the tissue caused by constipation, obesity or heavy lifting.
  
  
• Anal stenosis. The narrowing of the anal canal. This may occur as a birth defect in infants or from scarring after anal surgeries among adults. Current treatments can either dilate the anus or surgically remove scar tissue.
  
  
• Imperforate anus. A birth defect where the anal and rectal region is not properly developed. This occurs in around 1 in 5,000 infants, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). In some cases, the rectum does not connect to the anus (anorectal atresia). It may simply end or connect elsewhere, such as the urethra, bladder or vagina. In other cases, the anus may be very narrow or missing (anal atresia). In girls, a single opening may incorporate the rectum, vagina and bladder (congenital cloaca). These conditions require surgical correction.
  
  
• Hirschsprung’s disease. A rare congenital abnormality where the nerves to anal sphincters are not normally developed and infants are severely constipated because the sphincters do not relax.  Occasionally, a milder form is found in adults.  Surgery is usually required.
  
  
• Foreign bodies. Sometimes, objects may become stuck in the rectum or anus. These may be objects that have been swallowed (e.g., toothpicks) or objects inserted through the anus (e.g., enema tips, thermometers, objects used for sexual stimulation).