Anal Fissure - Symptoms, Causes, and Treatment

The anal fissure is a small tear in the skin around the anus, which can arise after trauma, such as passing hard and/or large feces during an evacuation. Anal fissure usually occurs in middle-aged people, but it is also a common cause of rectal bleeding in babies.

Painful bowel movements
Painful bowel movements

How do anal fissures arise?

Most anal fissures come after a trauma, usually an ankle fracture. The most common cause is bulky and hardened stools, which cause a stretch beyond the limit of the anal mucosa during evacuation. Other causes are anal sex or introduction of large diameter objects through the anus. Prolonged diarrhea can cause irritation and injury of the anal mucosa, facilitating cracking. Patients with a history of other anus lesions such as hemorrhoids or anal fistulas are also at increased risk. Women may develop fissures after a normal delivery.

Anal fissure usually occurs in people without other health problems, but it can also be a complication of some diseases, such as anorectal tuberculosis, Crohn's disease, leukemia.

The major problem with anal fissure is that it is a cyclical aggression process. The lesion of the musosa causes the sphincter of the anus involuntarily to suffer a spasm, preventing it to relax. This contraction of the anus causes more cleavage of the cleft, hampering the healing of the wound. Anal spasm, associated with painful bowel movements, exacerbates constipation. When the patient is finally able to evacuate, the stool is bulky and dry and must overcome the resistance of an anus, which has difficulty relaxing. All this causes even more mucosal injury and perpetuation of the fissure in the anus.

Patients who enter this vicious cycle often develop chronic anal fissures, as prolonged anal spasm, in addition to facilitating repetitive trauma, still causes compression of the blood vessels that irrigate the region of the anus, causing ischemia of this region. Chronic anal fissures are those that last longer than 6 weeks and do not heal without medical treatment.


Anal fissures usually arise in the tissue that lines the anal canal and the anal canal, a mucosa called anoderma. Unlike the skin, the anoderma has no hairs, sweat glands or sebaceous glands. On the other hand, this region is very rich in nerves responsible for transmitting the sensations of touch and pain, which explains why the anal fissures are so painful.

The anal fissure has the appearance of a cut or laceration in the region of the anus. If you imagine the anus as a pointer clock, with the patient lying belly up, the fissures are usually a laceration in the vertical direction, which occurs at 6 o'clock or 12 o'clock, as in the photos below. Cracks outside this location are usually caused by some other disease.

The main symptom of anal fissure is pain on bowel movement, which is usually very intense and can last for a few hours after the end of the evacuation. The pain is so strong that the patient begins to be afraid to evacuate, which can worsen intestinal constipation and make the stool even harder and bulky. In 70% of the cases also bleeds occur after the evacuation, which are usually of small quantity. There may be small drops of blood in the toilet, but the most common bleeding is just dirtying the toilet paper. Anal fissure can also cause itching and irritation in the anal area.

Fissure in the anus may have symptoms very similar to those of hemorrhoids, but bleeding from the fissure is usually minor and the pain more severe. Either way, the specialist for both injuries is the proctologist, who through examination of the anal region will be able to easily diagnose the cause of his pain. In most cases you do not need to perform a rectal touch to diagnose an anal fissure.


Anal fissure treatment is aimed at controlling pain and healing of laceration. In cases of small anal fissures, healing usually occurs spontaneously after a few days, but medical treatment can accelerate this process in addition to relieving pain.

Initial treatment may be homemade, with sitting baths with warm water three times a day, increased fiber intake and use of laxatives to decrease fecal stiffness.

There are some anal fissure ointments that can be used. Ointments based on nitroglycerin or nifedipine help to dilate the anal vessels, increasing the supply of blood and oxygen to the region of the fissure, which favors its healing. Nitroglycerin also helps to relax the anal sphincter, decreasing the cracking of the cleft and facilitating the act of evacuating. Nitroglycerin applications can cause headaches and dizziness as a side effect. Patients should avoid taking impotence medications, such as Viagra, during nitroglycerin treatment.

Ointments with anesthetics may also be used before each bowel movement to reduce pain, but pain alone does not aid in healing. About 90% of the fissures in the anus heal with conservative measures, such as those described above.

In cases that do not improve one can try the use of Botulinum toxin (Botox), which helps to relax the anal sphincter, reducing the stretch of the fissure. Botox may cause temporary loss of fecal continence as a side effect, and there may be small fecal losses for 2 or 3 months, time of toxin action.


Surgery is usually reserved for patients with anal fissure who have tried clinical treatment for at least one to three months without success. The procedure of choice is called internal lateral sphincterotomy, a small incision capable of causing the anal sphincter to relax. The surgery is very simple and the patient most often returns home the same day, being able to return to normal activities within a week.

The main concern with surgery is the development of anal incontinence, which may include inability to control the output of intestinal gas, mild fecal leakage or even loss of solid stools. Some degree of leakage of feces may occur in up to 45% of patients during the first postoperative days. However, this post-surgical incontinence is rarely permanent.

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