An intersphincteric abscess is a collection of pus that forms within the anal canal, specifically between the internal and external anal sphincter muscles. This localized infection is a type of anorectal abscess, occurring in the tissues surrounding the anus. The presence of pus indicates an infection.
Causes and Location of the Abscess
The anal canal contains small glands, typically numbering between four and ten, situated at the dentate line. These glands produce mucus to aid in stool passage. When a gland becomes blocked, its secretions can stagnate, leading to bacterial overgrowth and infection. This infection often originates in the cryptoglandular epithelium lining the anal canal.
The infection commonly forms an abscess within the intersphincteric space, between the internal and external anal sphincters. From this confined space, the infection can spread to adjacent perirectal areas. While a blocked anal gland is the most frequent cause, other factors can contribute, including inflammatory bowel conditions like Crohn’s disease, localized trauma, or a compromised immune system.
Key Symptoms and Indicators
Since an intersphincteric abscess develops deep within the anal canal, its symptoms often differ from superficial skin infections. The primary indicator is severe, constant, throbbing pain felt deep inside the rectum. This discomfort typically intensifies with sitting or during bowel movements, though it may not always be associated with a visible lump on the surface.
Beyond localized pain, individuals may experience systemic symptoms. These include a fever, chills, and a general feeling of being unwell. A discharge of pus or blood from the anal region may occur, though this is not always present, especially with deeper abscesses. The pain can become severe quickly if left untreated.
The Diagnostic Procedure
Confirming an intersphincteric abscess typically begins with a thorough clinical evaluation. This involves discussing symptoms and conducting a physical examination of the anal area. During a digital rectal examination, tenderness may be identified, but due to the deep location, a visible external swelling might not be apparent.
Imaging studies are often crucial for pinpointing the abscess. Common diagnostic tools include an endoanal or transrectal ultrasound, which uses sound waves to create images of internal structures. A computed tomography (CT) scan or magnetic resonance imaging (MRI) may also be used to provide detailed cross-sectional views. These imaging techniques help determine the size and location of the pus collection, which is necessary for planning the most effective treatment.
Surgical Treatment and Management
The definitive treatment for an intersphincteric abscess is surgical drainage. This procedure involves making an incision to open the abscess cavity and allow the infected material to drain. Drainage is typically performed under anesthesia to ensure patient comfort. The goal is to eliminate the infection and alleviate symptoms.
Following drainage, the wound is generally left open to heal from the inside out, a process known as healing by secondary intention. While antibiotics may be prescribed, they are usually considered supplementary to surgery. Antibiotics alone are often ineffective at resolving the infection because they struggle to penetrate the thick wall of the abscess cavity. Surgical drainage remains the primary and most effective approach to manage this condition.
Recovery and Associated Complications
After surgical drainage, recovery involves specific wound care to promote healing. Patients are often advised to take sitz baths to help keep the wound clean and reduce discomfort. Pain management is also a component of recovery, often involving prescribed or over-the-counter pain relievers. The healing timeline can vary, but diligent wound care supports the process.
A significant potential complication following the drainage of an intersphincteric abscess is the formation of an anal fistula. An anal fistula is an abnormal tunnel that connects the drained abscess cavity to the skin surface around the anus. This occurs in approximately one-third of patients. If a fistula develops, it requires a separate surgical procedure to close the abnormal tract, as it will not heal on its own.