What is an anal fissure?
An anal fissure is a tear in the lining of the lower rectum (anal canal) that causes pain during bowel movements. Anal fissures don’t lead to more serious problems.
Most anal fissures heal with home treatment after a few days or weeks. These are called short-term (acute) anal fissures. If you have an anal fissure that hasn’t healed after 8 to 12 weeks, it is considered a long-term (chronic) fissure. A chronic fissure may need medical treatment. Anal fissures are a common problem. They affect people of all ages, especially young and otherwise healthy people.
Pathophysiology and Etiology
The exact etiology of anal fissures is unknown, but the initiating factor is thought to be trauma from the passage of a particularly hard or painful bowel movement. Low-fiber diets (eg, those lacking in raw fruits and vegetables) are associated with the development of anal fissures. No occupations are associated with a higher risk for the development of anal fissures. Prior anal surgery is a predisposing factor because scarring from the surgery may cause either stenosis or tethering of the anal canal, which makes it more susceptible to trauma from the hard stool.
Initial minor tears in the anal mucosa due to a hard bowel movement probably occur often. In most people, these heal rapidly without long-term sequelae. In patients with underlying abnormalities of the internal sphincter, however, these injuries progress to acute and chronic anal fissures. Studies of the internal anal sphincter and of anal canal physiology have been performed with varied results, but at least one abnormality is likely to present in the internal anal sphincter of many anal fissure patients.
The most commonly observed abnormalities are hypertonicity and hypertrophy of the internal anal sphincter, leading to the elevated anal canal and sphincter resting pressures. The internal sphincter maintains the resting pressure of the anal canal; anal-rectal manometry can be used to measure this pressure. Most patients with anal fissures have elevated resting pressure, which returns to normal levels after surgical sphincterotomy.
The posterior anal commissure is the most poorly perfused part of the anal canal. In patients with hypertrophied internal anal sphincters, this delicate blood supply is further compromised, thus rendering the posterior midline of the anal canal relatively ischemic. This relative ischemia is thought to account for why many fissures do not heal spontaneously and may last for several months.
Pain accompanies each bowel movement as this raw area is stretched and the injured mucosa is abraded by the stool. The internal sphincter also begins to spasm when a bowel movement is passed. This spasm has two effects: First, it is painful in itself, and second, it further reduces the blood flow to the posterior midline and the anal fissure, contributing to the poor healing rate.
What causes an anal fissure?
Anal fissures can be caused by trauma to the anus and anal canal. The trauma can be caused by one or more of the following:
- Chronic (long-term) constipation
- Straining to have a bowel movement, especially if the stool is large, hard and/or dry
- Prolonged diarrhea
- Anal sex, anal stretching
- Insertion of foreign objects into the anus
Causes other than trauma include:
- Longstanding poor bowel habits
- Overly tight or spastic anal sphincter muscles (muscles that control the closing of the anus)
- Scarring in the anorectal area
- An underlying medical problem, such as Crohn’s disease and ulcerative colitis (types of inflammatory bowel disease); anal cancer; leukemia; infectious diseases (such as tuberculosis); and sexually transmitted diseases (such as syphilis, gonorrhea, Chlamydia, chancroid, HIV)
- Decreased blood flow to the anorectal area
Anal fissures are also common in young infants and in women after childbirth.
Risk factors of anal fissure
Factors that may increase your risk of developing an anal fissure include:
- Straining during bowel movements and passing hard stools increase the risk of tearing.
- Anal fissures are more common in women after they give birth.
- Crohn’s disease. This inflammatory bowel disease causes chronic inflammation of the intestinal tract, which may make the lining of the anal canal more vulnerable to tearing.
- Anal intercourse.
- Anal fissures can occur at any age but are more common in infants and middle-aged adults.
What are the signs and symptoms of anal fissures?
People with anal fissures almost always experience anal pain that worsens with bowel movements.
- The pain following a bowel movement may be brief or long-lasting; however, the pain usually subsides between bowel movements.
- The pain can be so severe that patients are unwilling to have a bowel movement, resulting in constipation and even fecal impaction. Moreover, constipation can result in the passage of a larger, harder stool that causes further trauma and makes the fissure worse.
- The pain also can affect urination by causing discomfort when urinating (dysuria), frequent urination, or the inability to urinate.
- Bleeding in small amounts, itching (pruritus ani), and a malodorous discharge may occur due to the discharge of pus from the fissure.
As previously mentioned, anal fissures commonly bleed in infants.
Complications of anal fissure
Complications seen with anal fissures include:
- Pain and discomfort
- Reduced quality of life
- Difficulty with bowel movements. Many people even avoid going to the bathroom because of the pain and discomfort it causes
- Possible recurrence even after treatment
- Uncontrolled bowel movements and gas
Your doctor will likely ask about your medical history and perform a physical exam, including a gentle inspection of the anal region. Often the tear is visible. Usually, this exam is all that’s needed to diagnose an anal fissure.
An acute anal fissure looks like a fresh tear, somewhat like a paper cut. A chronic anal fissure likely has a deeper tear and may have internal or external fleshy growths. A fissure is considered chronic if it lasts more than eight weeks.
The fissure’s location offers clues about its cause. A fissure that occurs on the side of the anal opening, rather than the back or front, is more likely to be a sign of another disorder, such as Crohn’s disease. Your doctor may recommend further testing if he or she thinks you have an underlying condition:
Anoscopy. An anoscope is a tubular device inserted into the anus to help your doctor visualize the rectum and anus.
Flexible sigmoidoscopy. Your doctor will insert a thin, flexible tube with a tiny video into the bottom portion of your colon. This test may be done if you’re younger than 50 and have no risk factors for intestinal diseases or colon cancer.
Colonoscopy. Your doctor will insert a flexible tube into your rectum to inspect the entire colon. This test may be done if you are older than age 50 or you have risk factors for colon cancer, signs of other conditions, or other symptoms such as abdominal pain or diarrhea.
Anal fissures often heal within a few weeks if you take steps to keep your stool soft, such as increasing your intake of fiber and fluids. Soaking in warm water for 10 to 20 minutes several times a day, especially after bowel movements, can help relax the sphincter and promote healing.
If your symptoms persist, you’ll likely need further treatment.
Your doctor may recommend:
- Externally applied nitroglycerin (Rectiv), to help increase blood flow to the fissure and promote healing and to help relax the anal sphincter. Nitroglycerin is generally considered the medical treatment of choice when other conservative measures fail. Side effects may include headaches, which can be severe.
- Topical anesthetic creams such as lidocaine hydrochloride (Xylocaine) may be helpful for pain relief.
- Botulinum toxin type A (Botox) injection, to paralyze the anal sphincter muscle and relax spasms.
- Blood pressure medications, such as oral nifedipine (Procardia) or diltiazem (Cardizem) can help relax the anal sphincter. These medications may be taken by mouth or applied externally and may be used when nitroglycerin is not effective or causes significant side effects.
If you have a chronic anal fissure that is resistant to other treatments, or if your symptoms are severe, your doctor may recommend surgery. Doctors usually perform a procedure called lateral internal sphincterotomy (LIS), which involves cutting a small portion of the anal sphincter muscle to reduce spasm and pain and promote healing.
Studies have found that for chronic fissure, surgery is much more effective than any medical treatment. However, surgery has a small risk of causing incontinence.
Self-help for anal fissures
Be guided by your health care professional, but general suggestions include:
- Apply petroleum jelly to the anus.
- See your chemist for advice on ointments specific for anal pain.
- Take regular sitz (salt bath) baths, which involves sitting in a shallow bath of warm water for around 20 minutes.
- Use baby wipes instead of toilet paper.
- Shower or bathe after every bowel motion.
- Drink six to eight glasses of water every day.
How can an anal fissure be prevented?
An anal fissure can’t always be prevented, but you can reduce your risk of getting one by taking the following preventive measures:
- Keeping the anal area dry
- Cleansing the anal area gently with mild soap and warm water
- Drinking plenty of fluids, eating fibrous foods, and exercising regularly to avoid constipation
- Treating diarrhea immediately
- Changing infants’ diapers frequently