Causes of Anal Fissure
An anal fissure (AY-nul FISH-er) is a tear in the anus causing a painful linear ulcer at the margin of the anus. An anal fissure, also known as fissure-in-ano, may cause itching, pain or bleeding. Fissures can extend upward into the lower rectal mucosa; or extend downward causing a swollen skin tab or tag to develop at the anal verge, also known as a sentinel pile.
Fissures with sentinel pile.
Anal Fissure as seen
through an anoscope.
Causes of Anal Fissure
Either extreme constipation or diarrhea, usually combined with nervous tension over a prolonged period of time, may produce anal abrasions, simple slit-like fissures, or acute ulcers at the anal verge. With constipation, this condition is usually caused by the passage of a hard dry stool that tears the anal lining upon defecation. With diarrhea, this condition is usually caused by an over use and over-wiping of an inflamed anal canal.
Because of an associated anal crypt infection, causing cryptitis, a fissure, an ulcer, or possibly even an abscess may occur at the superior aspect of the anal canal where it attaches to the lower rectal mucosa.
In some patients, the anal fissure doesn’t heal and becomes a painful sore that is constantly re-injured or torn with each bowel movement. The fissure usually develops a white fibrous base over time. Additionally, an external anal skin tag called a sentinel pile, and an enlarged papillae at the superior anal margin may develop.
A patient can pass shards of undigested material (i.e., stone ground corn chips, and sunflower seed shells) through the anus, tearing the anal skin, thus causing a fissure. Anal fissures also may be secondary to anorectal surgery, proctitis, tuberculosis, or cancer of the anus.
An anal fissure, a thin slit-like tear in the anal tissue, is likely to cause itching, pain, and bleeding during a bowel movement. View hemorrhoid gallery for a detailed photo.
A fissure produces pain at defecation and persists for hours. A small amount of bright red blood, which may or may not be mixed with stool, is common. A fissure produces pain disproportionate to its size. It is the third most painful common condition affecting the anus; the second most painful condition is an anal abscess, the first most painful condition is recovering from recent anal surgery.
Rarely, a spasm of the levator ani muscles, also known as proctalgia fugax, can be associated with chronic anal fissures. This condition may contribute to lack of healing of fissures… or may be caused by it.
Diagnosis can be made by inspection. Closer inspection will frequently reveal a tag or sentinel pile. After gentle separation of the skin of the anal verge, the ulcer usually posterior can be seen. Frequently the fibers of the internal anal sphincter muscle can be seen at the base of this punched-out ulcer. A well-lubricated finger with lidocaine ointment and a small caliber anoscope will help delineate the extent of the lesion. A colonoscope or sigmoidoscope exam might be useful to rule out abscesses, colitis, and other causes of rectal bleeding.
A fissure should be distinguished from an ulcer caused by Crohn’s disease, leukemia, or malignant tumors, because it is not shaggy, large or indolent. Fissures are seldom multiple. A biopsy can help to determine the diagnosis.
At least 50 percent of fissures heal by themselves without the need for an operation. The longer that a fissure has persisted over time, the less likely it will be to heal by itself. Oftentimes, acute fissures heal by themselves spontaneously, with good anal hygiene consisting of a thorough cleansing after each bowel movement with cotton and witch hazel. Cleaning gently after bowel movements with thick quilted baby wipes is just as effective as using cotton pads with witch hazel. The use of sitz baths (soaking the anal area in plain warm water for 20 minutes, several times a day) helps to relieve fissure symptoms, but may not actually aid in the healing process. A topical hydrocortisone preparation applied to the folds of the anal verge several times a day will help to relieve symptoms and aids the healing process.
A high fiber, well balanced diet, and encouragement of regular normal stools are important in helping to heal the fissure. If pain is severe, an anesthetic ointment can be introduced freely and frequently with the finger, utilizing finger cots.
Chemical sphincterotomy has been attempted using a wide range of agents, including nitric oxide and botulinum toxin. Since anal fissures are characterized by spasm of the internal anal sphincter and a reduction in mucosal blood flow, the aim of treatment is to relieve ischemia by reducing resting anal pressure and improving mucosal perfusion.
It has been shown that a local application of topical nitrates reduces anal sphincter pressure and improves anodermal blood flow. This dual effect results in fissure healing in more than 80% of patients. The principal side effect is headaches in 20%-100% of cases.
It has also been shown that local a local injection of botulinum toxin near the fissure, causes denervation, sphincter muscle weakness, and reduction of resting anal sphincter pressure, which allows the fissure to heal. Fissure healing occurs in more than 60% of patients. The principal side effect is incontinence of flatus and or feces, which last for up to two months in 2% to 21% of cases.
When surgical excision is required, the chronic fissure along with the sentinel pile, papilla, and adjacent crypts are dissected free from the underlying muscle. Associated internal and external hemorrhoids are removed. Usually the scar tissue in the posterior anal quadrant is completely denuded. The criteria for excision of fissures are chronicity and association with other anorectal disease such as hemorrhoids, mucosal prolapse, skin tags, enlarged papillae, anal contraction, and diseased crypts.
Sometimes, an anal dilation is performed to gently disrupt the scar tissue in the base of the fissure. Other times, cauterization by: laser, electrosurgical, or a chemical (i.e., silver nitrate) method; is used to simply denude or resurface the fissure base, to encourage the growth of new anal tissue.
Lateral partial internal sphincterotomy has been utilized for uncomplicated fissures. This surgery consists of a small operation to cut a portion of the anal muscle. This helps the fissure to heal by preventing pain and spasm, which interferes with healing. Cutting this muscle rarely interferes with the ability to control bowel movements.
At least 90% of patients who require surgery for this problem have no further trouble from fissures. More than 95% of patients achieve prolonged symptomatic improvement. About 5-percent of patients with fissures are “chronic fissure formers”, and for a variety of reasons (i.e., chronic constipation, failure to heal without scar tissue, etc.), will continue to develop new fissures despite all the efforts of medical and surgical treatment.