ROSH Gastrointestinal Practice Exam

Where is the most common location for primary anal fissures?

1. Anterolateral to the midline

2. Lateral to the midline

3. Posterior midline

4. Anterolateral to the midline

The correct answer is: Posterior midline

Primary anal fissures most commonly occur in the posterior midline. This is due to the anatomy and blood supply of the anal canal, where the posterior area is less vascularized compared to other regions. As a result, it is more susceptible to trauma, which can lead to the development of fissures. Traumatic events such as passing hard stools or straining during a bowel movement can result in tears in the anal epithelium, particularly in the posterior area. While anterior fissures can occur, they are much less common and are often associated with specific conditions, such as inflammation or underlying disease. The lateral regions also do not typically present with primary fissures unless there are predisposing factors present. Therefore, recognizing that the posterior midline is the primary location for such fissures is essential for diagnosis and treatment in gastrointestinal health.