Rosh Emergency Medicine Practice Test

What exam finding is most likely with a suspected anal fissure in a patient with a history of constipation?

1. Dilated and prolapsed purple-colored veins

2. Longitudinal tear in the anterior midline

3. Longitudinal tear in the posterior midline

4. Perianal red opening with purulent discharge

The correct answer is: Longitudinal tear in the posterior midline

In the context of a suspected anal fissure, particularly in a patient with a history of constipation, the most common finding is a longitudinal tear that typically occurs in the posterior midline of the anal canal. Anal fissures are often associated with trauma to the anal mucosa, which can happen during the passage of hard or large stools, as is frequent with constipation. The anatomical position of the fissure is crucial; the posterior midline is the most common site due to the inherent mechanics and pressure distribution during defecation. This is where the tears often develop, presenting as a painful crack or tear that can cause significant discomfort and even bleeding during bowel movements. Other options might represent conditions that are related but do not fit the typical presentation of an anal fissure in this clinical scenario. For instance, dilated and prolapsed purple-colored veins suggest hemorrhoids, which are a different condition. A longitudinal tear in the anterior midline, while possible, is less common and usually provides a differential diagnosis. Finally, a perianal red opening with purulent discharge might indicate an infection, such as an abscess or fissure with secondary infection, which also does not align with the classic presentation of an anal fissure associated with constipation. Recogn