A perianal abscess primarily arises from infection of the anal glands located in the intersphincteric space, which leads to the formation of a pus-filled cavity near the anus. This infection typically results from obstruction of the anal glands, allowing bacterial overgrowth and abscess formation. The most common causative organisms are polymicrobial, including anaerobic and aerobic bacteria from the gut flora. Other contributing factors include local trauma, anal fissures, inflammatory bowel disease (such as Crohn's disease), and immunosuppression, which can predispose to abscess development. Additionally, conditions that impair local drainage or immune response may increase the risk of abscess formation. Thus, the pathogenesis involves a combination of gland obstruction, bacterial invasion, and host factors that facilitate infection and abscess formation.
This understanding is supported by UK clinical guidelines and reinforced by recent literature, which emphasize the role of anal gland infection as the primary cause, with secondary factors such as trauma and systemic disease influencing susceptibility Sahnan et al. 2017Amato et al. 2020 NICE CKS.
Key References
- CKS - Pruritus ani
- CKS - Anal fissure
- Macrogol 3350 with potassium chloride, sodium bicarbonate and sodium chloride SmPC
- Lactulose SmPC
- Ispaghula husk SmPC
- (Sahnan et al., 2017): Perianal abscess.
- (Amato et al., 2020): Evaluation and management of perianal abscess and anal fistula: SICCR position statement.
- (Newton et al., 2022): Postoperative Packing of Perianal Abscess Cavities (PPAC2): randomized clinical trial.