Anal fissure overview

# Overview
Anal fissure is linear tear in the anal skin. Historically, there is description of anal fissure by Louis Lemonnier in his Traite de la fistule de lanus ou du fondement (1689). Anal fissures can be divided into primary and secondary anal fissures based on etiology, posterior and anterior anal fissures based on location, and acute and chronic anal fissures based on the duration of symptoms.The exact pathogenesis of anal fissure is not fully understood but constipation or anal trauma was supposed to instigate the fissure. It is understood that anal fissure is the result of either anal trauma (by hard stools/diarrhea), perfusion defects with ischemia caused due to increased anal pressures and decreased blood flow or increased anal sphincter tone. In 90% of the patients, anal fissures are found in posterior midline. A small tear is seen that extends from dentate line to anal verge due to ischemia/poor perfusion of the area by inferior rectal artery (during increased sphincter tone). Anal fissure are caused due to severe and chronic constipation, watery diarrhea and Crohn's disease. Anal fissures are common in women after childbirth, and following constipation in infants. Other less common causes include tuberculosis, sarcoidosis, anal intercourse, HIV , Human papillomavirus, and syphilis. Anal fissure are caused due to severe and chronic constipation, watery diarrhea and Crohn's disease. Anal fissures are common in women after childbirth, and following constipation in infants. Other less common causes include tuberculosis, sarcoidosis, anal intercourse, HIV , Human papillomavirus, and syphilis. The incidence of anal fissure is approximately 1100 per 100,000 individuals in US which is about 7.8% lifetime risk. The incidence is 30-50% in patients with Crohn's disease. Women in adolescence and child bearing group and males of middle aged group are commonly affected. Females are more affected than males. The symptoms of anal fissure can develop in infants as well as in adults following episodes of severe and chronic constipation and diarrhea. If left untreated, the unhealed fissures can get complicated to chronic fissures, anal abscess, anal fistula and fecal incontinence. The prognosis is generally excellent and 90% spontaneously heal or with dietary and medical measures. Patients with anal fissure have a history of painful bowel movements and bleeding per rectum which can be seen as blood on tissue paper following a bowel movement. They usually have a history of constipation too but also some patients may report frequent episodes of watery diarrhea.They also have symptoms of painful defecation.Some patients may also have associated itching and irritation. Patients with anal fissure usually appear in pain. Physical examination of patients with anal fissure is usually remarkable for painful skin laceration, skin tags in the chronic anal fissure. Most common cause of anal fissure is straining when constipated. For treatment of constipation, click here. Anal fissures in infants usually self-heal without anything more than frequently changing diapers and treating constipation if it is the cause. The topical therapy is the first line of treatment along with dietary and other conservative measures. Analgesia with lidocaine and vasodilators like nitroglycerin and nifedipine are chiefly used for the topical management. Botulinum toxin can be effective in 89% cases. It is reserved for the people who can't undergo surgery for high risk of incontinence. Surgery is the option after trying the conservative and medical measures and its done in patients not responding to them, with chronic anal fissures and where fissures are complicated by fistulas and abscess. Lateral internal sphincterotomy is the procedure of choice. The complications of the surgery include fecal incontinence and therefore contraindicated in the patients having fecal incontinence. In these patients, anal advancement flap or Botulinum toxin is used.

# Historical Perspective
There is description of anal fissure by Louis Lemonnier in his Traite de la fistule de lanus ou du fondement (1689). In 1989, Klosterhalfen et al discovered a scarcity of small arteriolar collaterals between the end branches of the left and right inferior rectal artery dorsally during post-mortem angiographic studies.  Botulinum toxin injection, administered by colorectal surgeons to relax the sphincter muscle and its use for this condition was first investigated in 1993.In 1994, Shouten et al discovered the association between anal pressure and the anodermal blood flow indicating development of anal fissure. This work also showed that there is significantly lower blood flow at the fissure site than other places.

# Classification
Anal fissures can be divided into primary and secondary anal fissures based on etiology, posterior and anterior anal fissures based on location, and acute and chronic anal fissures based on the duration of symptoms.

# Pathophysiology
The exact pathogenesis of anal fissure is not fully understood but constipation or anal trauma was supposed to instigate the fissure. It is understood that anal fissure is the result of either anal trauma (by hard stools/diarrhea), perfusion defects with ischemia caused due to increased anal pressures and decreased blood flow or increased anal sphincter tone. In 90% of the patients, anal fissures are found in posterior mid line. A small tear is seen that extends from dentate line to anal verge due to ischemia/poor perfusion of the area by inferior rectal artery (during increased sphincter tone).

# Causes
Anal fissure are caused due to severe and chronic constipation, watery diarrhea and Crohn's disease. Anal fissures are common in women after childbirth, and following constipation in infants. Other less common causes include tuberculosis, sarcoidosis, anal intercourse, HIV , Human papillomavirus, and syphilis.

# Differentiating Anal fissure overview from Other Diseases
Anal fissure must be differentiated from other diseases that cause anal discomfort and pain with defecation such as hemorrhoids, rectal prolapse and perianal abscess, anal fistula and anal cancer.

# Epidemiology and Demographics
The incidence of anal fissure is approximately 1100 per 100,000 individuals in US which is about 7.8% lifetime risk. The incidence is 30-50% in patients with Crohn's disease. Women in adolescence and child bearing group and males of middle aged group are commonly affected. Females are more affected than males.

# Risk Factors
The common risk factors for anal fissure include people with chronic constipation, frequent diarrhea, anal trauma, labor complication to the mother, Crohn's disease. Less common risk factors include infants, elderly adults, and people having HIV.

# Screening
There is insufficient evidence to recommend routine screening for anal fissure.

# Natural History, Complications, and Prognosis
The symptoms of anal fissure can develop in infants as well as in adults following episodes of severe and chronic constipation and diarrhea. If left untreated, the unhealed fissures can get complicated to chronic fissures, anal abscess, anal fistula and fecal incontinence. The prognosis is generally excellent and 90% spontaneously heal or with dietary and medical measures.

# Diagnosis

## History and Symptoms
Patients with anal fissure have a history of painful bowel movements and bleeding per rectum which can be seen as blood on tissue paper following a bowel movement. They usually have a history of constipation too but also some patients may report frequent episodes of watery diarrhea.They also have symptoms of painful defecation.Some patients may also have associated itching and irritation.

## Physical Examination
Patients with anal fissure usually appear in pain. Physical examination of patients with anal fissure is usually remarkable for painful skin laceration, skin tags in the chronic anal fissure. A tear is usually seen in the posterior part of anal canal(90)% and in anterior or middle part(10%). Patient usually resists use of anoscope due to the pain. Acute anal fissures appear as fresh laceration while chronic have raised margins.

## Laboratory Findings
Primary anal fissure is usually diagnosed and confirmed by clinical history and physical examination. Laboratory findings are needed to rule out the causes of secondary anal fissures e.g. Crohn's disease,tuberculosis, sarcoidosis and HIV which include Leukocytosis- lymphocytosis,Enzyme linked immunosorbent assay (ELISA).

## Imaging Findings
There are no other imaging findings associated with anal fissure.

## Other Diagnostic Studies
There are no other diagnostic studies associated with anal fissure.

# Treatment

## Medical Therapy
Most common cause of anal fissure is straining when constipated. For treatment of constipation, click here. Anal fissures in infants usually self-heal without anything more than frequently changing diapers and treating constipation if it is the cause. The topical therapy is the first line of treatment along with dietary and other conservative measures. Analgesia with lidocaine and vasodilators like nitroglycerin and nifedipine are chiefly used for the topical management. Botulinum toxin can be effective in 89% cases. It is reserved for the people who can't undergo surgery for high risk of incontinence.

## Surgery
Surgery is the option after trying the conservative and medical measures and its done in patients not responding to them, with chronic anal fissures and where fissures are complicated by fistulas and abscess. Lateral internal sphincterotomy is the procedure of choice. The complications of the surgery include fecal incontinence and therefore contraindicated in the patients having fecal incontinence. In these patients, anal advancement flap or Botulinum toxin is used.

## Prevention
Effective measures for the primary prevention of anal fissure include frequent diaper change in infants and preventing constipation. In adults, the approach is to prevent constipation and treating it appropriately by adopting dietary measures like eating diet rich in fibers , drinking water and also stool softener if needed. Treating diarrhea and to prevent straining in the toilet. Keeping anal hygiene and avoiding anal intercourse.