Doctors don't entirely understand the cause of this condition. But theories include direct injury to the affected area or decreased blood flow to the area (ischemia).

Such an injury or blood loss may occur in cases of rectal prolapse, a condition in which the rectal mucous membrane, or lining, moves down or through the anus. This is particularly true when accompanied by contraction of the muscle that circles the front portion of the upper anal canal (puborectalis muscle). The combination of downward pressure and movement of the mucous lining and stool when defecating and the upward pressure from the puborectalis muscle contraction may create enough pressure to injure the rectum. The pressure may also limit blood flow to the area.

However, not everyone with solitary rectal ulcer syndrome experiences these conditions, and experts don't know whether rectal prolapse causes ulcers or whether the prolapse and the ulcers are both signs of a similar disease.

Other causes of injury and subsequent ulcers may include:

Constipation or impacted stool
Attempts to manually remove impacted stool
Straining during defecation
Radiation treatment that limits blood flow to the area
Use of ergotamine suppositories, an anti-migraine treatment
Risk factors
Solitary rectal ulcer syndrome occurs equally in men and women. It can affect people of all ages, but appears to be especially common in middle age.

Although the cause of solitary rectal ulcer syndrome isn't clear, conditions such as chronic constipation, straining during bowel movements, rectal prolapse, and using your finger to remove stool when you are constipated may increase your risk of rectal ulcers. Although these conditions have been associated with increased risk, you can develop rectal ulcers without any of these conditions.

When to seek medical advice
A common sign of rectal ulcers is rectal bleeding. But because rectal bleeding can occur for other reasons, see your doctor to rule out other conditions or diseases. Other causes of bleeding in the lower gastrointestinal tract include anal fissure, colorectal cancer and anal cancer.

If the onset of your signs or symptoms occurs along with a marked change in bowel habits or if you're passing bloody, black, tarry or maroon stools, consult your doctor without delay. These types of stools can signal more extensive bleeding elsewhere in your digestive tract.

Seek emergency care if you notice large amounts of rectal bleeding, lightheadedness, dizziness or faintness.

Because solitary rectal ulcer syndrome is rare, it's best diagnosed and treated by a specialist in disorders of the colon and rectum.

Tests and diagnosis
In addition to asking about your signs and symptoms, your doctor may use the following tests to assess whether you have rectal ulcers:

Sigmoidoscopy. In this test, your doctor uses a flexible, slender and lighted tube to examine your rectum and part of your colon. The test usually takes just a few minutes. It can sometimes be uncomfortable, and there's a slight risk of perforating the colon wall. If your doctor finds a lesion, he or she may take a sample biopsy to examine it under a microscope and confirm the diagnosis.
Ultrasound. Your doctor may also use a test called a transrectal or endoanal ultrasound to help differentiate solitary rectal ulcer syndrome from other conditions such as cancer.

The procedure uses a device called a transducer, which generates and receives high-frequency sound waves that can't be heard by the human ear. The transducer then sends this information to a computer, which composes detailed images based on the patterns created by the sound waves. In this procedure, the ultrasound transducer is inserted into your rectum.

If the test reveals thickening of the rectal wall and internal anal sphincter, for example, it may suggest solitary rectal ulcer syndrome.

Defecation proctography. During this test, your doctor inserts barium paste, a soft, metallic alkaline chemical, into your rectum. You then pass the barium paste as you would stool. The barium appears clearly on X-rays, allowing your doctor to look for abnormalities in muscle function or coordination. This test can reveal a rectal prolapse, a puborectalis muscle that isn't relaxing and delayed rectal emptying.
Treatments and drugs
Treatment of a rectal ulcer depends on your symptoms and whether you also have rectal prolapse. If you don't have any symptoms or your symptoms are mild, treating and preventing constipation, such as by increasing fiber and fluid intake, often improve symptoms and heal the ulcer.

If your symptoms are more severe or you have rectal prolapse, other therapies may include:

Enemas. Sucralfate enemas contain an aluminum salt and work by coating the ulcer and creating a barrier against irritants that may allow the ulcer to heal. Corticosteroid enemas and 5-aminosalicylic acid enemas also may help decrease inflammation and aid ulcer healing.
Biofeedback. Using feedback from a variety of monitoring procedures and equipment, a biofeedback specialist will try to teach you to control certain involuntary body responses, such as straining during defecation. This therapy may need to be repeated within a few years of your initial course of treatment.
Surgery. Surgery is especially useful when the condition is recurrent and accompanied by rectal prolapse. Surgery may include removal of the lesions. It may also include fecal diversion, which is the use of an ostomy — a surgically created opening in which a portion of the colon above the rectum is brought to the abdominal surface. There, stool is expelled into a pouch or bag that you empty.
Rectopexy, another surgical option, corrects rectal prolapse by using stitches to secure the rectum in its anatomically correct position.