A perianal abscess is a collection of pus that develops in the tissues surrounding the anal canal. This condition occurs when small glands within the anus become blocked and infected. This article provides an overview of a perianal abscess, including its appearance, symptoms, causes, and medical treatments.
Visual Identification and Symptoms
A perianal abscess appears as a swollen, red, and tender lump near the anus, which may resemble a boil and feel warm. The primary symptom is a constant, throbbing pain in the area that worsens with sitting, coughing, or bowel movements. This pain can develop and intensify over a few days.
The area will feel tender and may be firm or have a fluid-filled quality. In some instances, the abscess may rupture on its own, releasing foul-smelling pus. As the infection progresses, systemic symptoms like fever, chills, and fatigue can develop, indicating the body is fighting a significant infection. Constipation can also occur because the pain makes passing stool difficult.
Underlying Causes
The formation of a perianal abscess is initiated by an infection in the small, mucus-secreting glands inside the anus. When a gland is obstructed by bacteria or fecal matter, the trapped bacteria multiply, leading to a pus-filled cavity. This process accounts for nearly 90% of all anal abscesses.
Certain health conditions increase a person’s susceptibility to developing a perianal abscess. These risk factors include:
- Inflammatory bowel disease, particularly Crohn’s disease, due to chronic inflammation.
- Compromised immune systems, such as from diabetes or HIV.
- Anal fissures, which are small tears in the anal lining that can allow bacteria to enter.
- Some sexually transmitted infections.
Medical Evaluation and Treatment
A diagnosis is made through a physical examination. A healthcare provider will inspect the perianal area, and a digital rectal exam may be performed to assess the extent of the abscess. If the abscess is not easily visible or is located deeper, imaging tests like an ultrasound or CT scan can confirm the diagnosis and determine its precise location and size.
The standard treatment is a procedure called incision and drainage (I&D). A doctor makes a small incision over the abscess to allow the pus to drain, which provides immediate pain relief. This procedure is often performed in a doctor’s office or an emergency room. Following drainage, antibiotics may be prescribed if the infection is severe or if the patient has other health conditions. Patients are also advised to take sitz baths, which involve soaking the anal area in warm water, to aid healing.
Differentiating from Similar Conditions
A professional medical evaluation is necessary to distinguish a perianal abscess from other conditions with similar symptoms. One such condition is a thrombosed hemorrhoid, which is a painful lump caused by a blood clot in an external hemorrhoid but does not involve pus or fever.
Another condition is an anal fissure, a small tear in the anal lining. A fissure causes sharp pain and bleeding with bowel movements but does not present as a swollen, pus-filled lump. The pain from a fissure is often described as feeling like passing glass, which differs from the constant, throbbing pain of an abscess.
An anal fistula is a related complication where a small tunnel forms between the infected gland and the skin. This can cause persistent drainage and may lead to recurrent abscesses if not treated. Distinguishing between these conditions is important, as the treatment for each is different.