What is the most common type of anal fissure?

The most common type of anal fissure is the posterior fissure. This type of fissure typically occurs at the 6 o'clock position and is more prevalent due to several anatomical and physiological factors.

The posterior anal fissure is often associated with conditions that lead to increased anal pressure or trauma, such as constipation or straining during bowel movements. The posterior location has a greater chance of exposure to trauma from fecal matter, and some patients may have associated factors like hemorrhoids or other issues that compromise the area. The rich nerve supply and the thinner skin at the anal verge make the area more susceptible to fissuring under stress.

In contrast, the anterior fissure is less common and typically seen in women, which may be linked to factors such as pregnancy and childbirth. Lateral fissures and intersphincteric fissures are rare and can be associated with certain underlying conditions, including Crohn’s disease or specific forms of anal pathology.