Anal Fissures

Anal Fissure


An anal fissure (fissure-in-ano) is a small, oval shaped tear in skin that lines the opening of the anus.  The location of the fissure is inside the anal canal posterior or anterior where the internal and external anal sphincters are located.  The fissure occurs only in the skin (the thin anoderm) that the internal anal sphincter is covered by in the anal canal. A fissure occurs when the sphincter does not relax fast enough or completely enough or if the skin is too friable or too rigid for the delivery of the stool. Fissures typically cause severe pain and bleeding with bowel movements.  At times chronic anal fissures can be pain free and not bleed the only symptoms is the inability to pass stool (straining to stool against a closed sphincter). Fissures are quite common in the general population, but are often confused with other causes of pain and bleeding, such as hemorrhoids.


The typical symptoms of an acute anal fissure include severe pain during, and especially after, a bowel movement, lasting from several minutes to a few hours.  Patients may also notice bright red blood from the anus that can be seen on the toilet paper or on the stool.  Between bowel movements, patients with an acute anal fissure are often relatively symptom-free. Patients with chronic anal fissures can have pain all of the time.  Particularly if the chronic anal fissure has created a hole deep enough in the skin to cause an intersphincteric abscess. Many patients with chronic anal fissures are fearful of having a bowel movement and may try to avoid defecation secondary to the pain.  Others may not be able to have a normal formed stool because the sphincter muscle or the skin can not relax to allow passage of the stool.  Patients in this setting complain of constipation but in fact have difficulty with evacuation of stool out of the anus not passage of stool through the colon. Note that this is the same symptom one would have if they had a rectal cancer. Once the fissure is healed the constipation and problems with evacuation should also cease.  A followup colonoscopy is important if the bleeding and constipation persist after surgery.


Fissures are usually caused by trauma to the inner lining of the anus. The typical patient is a young female taking prenatal vitamins with iron, a constipating agent, which makes large very hard stools as iron slows the movement of stool through the gastrointestinal tract. Another typical patient would be a postoperative patient who has been placed on narcotics for pain.  Patients with recurrent acute anal tearing will develop a hypertrophied or tight internal anal sphincter muscles (i.e., increased muscle tone) which then exacerbates the development of anal fissures.  An acute anal fissure occurs when a large, hard, dry bowel movement moves through the anus.  Loose stools and diarrhea are a more common cause particularly when there is a hard small stool followed by diarrhea which rapidly propels the stool through the closed anal sphincter causing trauma or a tear of the anus.  Following a bowel movement, severe anal pain can produce spasm of the anal sphincter muscle, resulting in a decrease in blood flow to the site of the injury, thus impairing healing of the wound. The spasm results in the internal anal sphincter which is the smooth muscle of the anus getting bigger, hypertrophy of the internal anal sphincter. The next bowel movement results in more pain, anal spasm, decreased blood flow to the area, and the cycle continues.  The muscle continues to get bigger the fissure more painful and eventually the patient can not have a normal stool and resorts to having only small soft stools. Treatments are aimed at interrupting this cycle by relaxing the anal sphincter muscle to promote healing of the fissure.  Dilation of the muscle will stop the spasm and is the most effective treatment, therefore focus on bulking agents and large formed anal friendly stools.

Other, less common, causes of an anal fissure include hemorrhoid surgery, inflammatory conditions, chronic diarrhea and certain anal infections, radiation treatment or tumors.  Anal fissures may be acute (recent onset) or chronic (present for a long period of time).  Chronic fissures may be more difficult to treat, and may also have an external lump outside the anus associated with the tear, called a sentinel pile or skin tag, as well as extra tissue just inside the anal canal sometimes called a hypertrophied papilla.


The majority of anal fissures do not require surgery.  The most common treatment for an acute anal fissure consists of making the stool more formed and bulky with a diet high in fiber and utilization of over-the-counter fiber supplementation (totaling 25-35 grams of fiber/day). This does not mean use stool softners.  Stool softeners will make an acute anal fissure worse.  Stool softeners and increasing water intake may be necessary to promote soft bowel movements if the patient has a chronic anal fissure until surgery.  Topical anesthetics for pain and warm tub baths (sitz baths) for 10-20 minutes several times a day (especially after bowel movements) are soothing and promote relaxation of the internal anal sphincter muscle, which may help the healing process.

Other medications (such as nitroglycerin, nifedipine, or diltiazem) may be prescribed that allow relaxation of the anal sphincter muscles. Your surgeon will go over benefits and side-effects (generally a severe headache) with you.

Narcotic pain medications are not recommended for anal fissures, as they promote constipation and make the fissure worse.

Chronic fissures require surgical treatment.


Fissures can recur easily, and it is quite common for a fully healed fissure to recur after a hard bowel movement or other trauma.  Even when the pain and bleeding have subsided, it is very important to continue good bowel habits, exercise and a diet high in fiber as a lifestyle change.  If the problem returns without an obvious cause, further assessment is warranted.


A fissure that fails to respond to conservative measures should be re-examined. Sometimes the fissure is chronic and will require surgery.  Persistent hard or loose bowel movements, scarring, or spasm of the internal anal muscle all contribute to delayed healing.  Other medical problems such as inflammatory bowel disease (Crohn’s disease), infections, or anal tumors can cause symptoms similar to anal fissures.  Patients suffering from persistent anal pain or problems with evacuation of stool should be examined to exclude these symptoms.  This may include a colonoscopy or an exam in the operating room under anesthesia.


The cause of a chronic anal fissure is the hypertrophy or over growth of the internal anal sphincter.  The muscle is a smooth muscle and cannot relax for defecation.  The patient experiences an inability to pass stool through the anal canal.  The stool gets stuck and the patient cannot force the stool through as the sphincter will not relax.  The patient has to dig the stool out or has to have only diarrhea as no formed stool will come through the anus.  If the internal anal sphincter could be made to relax and atrophy for 3 months and the patient is able to stool normal stools no longer traumatizing the anus then the internal anal sphincter muscle will shrink as any muscle does that is not used.  Surgical options for treating anal fissure employ this notion and include Botulinum toxin (Botox®) injection into the anal sphincter and surgical division of a portion of the internal anal sphincter (lateral internal sphincterotomy).  Both of these are performed typically as outpatient, same-day procedures, or occasionally in the office setting.  The goal of these surgical options is to promote atrophy or shrinking of the anal sphincter, thereby decreasing anal pain and spasm, allowing the fissure to heal.  Botox® injection results in healing in 50-80% of patients and generally takes 3-4weeks, while sphincterotomy is immediately effective and reported to be over 90% successful. If a sentinel pile is present, it may be removed to promote healing of the fissure.  All surgical procedures carry some risk, when performed by a skilled surgeon a sphincterotomy can rarely interfere with one’s ability to control gas and has never been found to be responsible for incontinence to stool as the external anal sphincter is not divided.  A colon and rectal surgeon which is the only specialist in trained in surgical proctology will discuss these risks with you to determine the appropriate treatment for your particular situation.


It is important to note that complete healing with both medical and surgical treatments can take up to approximately 6-10 weeks. However, acute pain after surgery often disappears after a few days.  Most patients will be able to return to work and resume daily activities in a few short days after the surgery. If a closed sphincterotomy is performed most patients are back to there regular activities within 24 hours.  It is important to recognized the incision made for a sphincterotomy surgery is only the width of a piece of paper less than a millimeter.  The normal size or thickness of the internal anal sphincter is the width of a piece of paper.  When the muscle hypertrophies it doubles in size to the size of two pieces of paper.  The recovery from this surgery is therefore minimal.  Many times the surgery involves not just a sphincterotomy but also hemorrhoids, an abscess or a fistula.  These operations require some additional recovery time.


Absolutely not.  Persistent symptoms, however, need careful evaluation since other conditions other than an anal fissure can cause similar symptoms.  Your colon and rectal surgeon may request additional tests, even if your fissure has successfully healed.  A colonoscopy may be required to exclude other causes of rectal bleeding. An chronic anal fissure just as any chronic wound can cause squamous cell cancer if the fissure has been present for many years so it is always important to have your physician biopsy a fissure. Even small anal fissures can represent an early cancer.