Page 2 - 01- Anal Fissure

ANAL FISSURE
Anne Walsh, ANP-BC Jennifer Grumet, MD

BASICS

DESCRIPTION
Anal fissure (fissure in ano): longitudinal tear in the lining of the anal canal distal to the dentate
line, most commonly at the posterior midline; characterized by a knifelike tearing sensation on
defecation, often associated with bright red blood per rectum. This common benign anorectal
condition is often confused with hemorrhoids; may be acute or chronic (>8 weeks) in duration or
with the presence of hypertrophic papilla and sentinel pile (skin tag).
EPIDEMIOLOGY
Affects all ages. Common in infants aged 6 to 24 months; not common in older children,
suspect abuse, or trauma; elderly less common due to lower resting pressure in the anal canal
Sex: male = female; women more likely to get anterior midline fissures (25%) versus men
(8%)

Incidence
Exact incidence is unknown (1). Patients often treat with home remedies and do not seek medical
care.
Prevalence
80% of infants, usually self-limited
10–20% of adults, most of whom do not seek medical advice

ALERT
Lateral fissure: Rule out infectious disease.
Atypical fissure: Rule out Crohn disease.

ETIOLOGY AND PATHOPHYSIOLOGY
High-resting pressure within the anal canal (usually as a result of constipation/straining) coupled
with decreased perfusion of the posterior canal leads to ischemia of the anoderm, resulting in
splitting of the anal mucosa during defecation and spasm of the exposed internal sphincter.

Genetics
None known

RISK FACTORS
Constipation (25% of patients)
Diarrhea (6% of patients)
Passage of hard or large-caliber stool
High-resting pressure of internal anal sphincter (prolonged sitting, obesity)
Trauma (sexual activity or abuse, foreign body, childbirth, mountain biking)
Prior anal surgery with scarring/stenosis
Inflammatory bowel disease (Crohn disease)
Infection (chlamydia, syphilis, herpes, tuberculosis)