Perianal Abscesses - Causes, Symptoms, Risk Factors, Diagnosis, Treatment, and Prevention

Introduction:

An abscess is the localized collection of infected fluid. A perianal abscess is a condition in which the collection of pus develops near the anus. Anorectal abscesses are subdivided according to their location, and perianal abscesses represent the common type constituting 60 % of the cases. It is a painful condition and can cause discomfort to patients. The terms "anal abscess" and "rectal abscess" also describe this condition. Anal abscesses are caused by the infection of the anal glands. It can occur over 40 years of age, and adult males are more likely to be affected. The condition can affect infants and toddlers who are still in diapers. They can also cause systemic infection if left untreated.

What Are the Causes of a Perianal Abscess?

The following reasons can cause a perianal abscess:

• An infected anal fissure, tear in the anal canal.

• Blockage of anal glands.

• Sexually transmitted infections.

The disease-causing microorganisms include both aerobic and anaerobic organisms. For example, Escherichia coli was the predominant pathogen isolated from perianal abscesses in patients without diabetes, and Klebsiella pneumoniae was the dominant organism found in diabetic patients.

What Are the Risk Factors of Perianal Abscess?

The following factors can increase the risk of perianal abscesses:

• Inflammatory bowel disease such as ulcerative colitis or Crohn's disease.

• Diabetes.

• Pelvic inflammatory disease.

• Smoking.

• Diarrhea.

• Recent chemotherapy.

• Constipation.

• Human immunodeficiency virus (HIV) infection.

• Use of medications such as Prednisone.

• Being the recipient partner in anal sex.

What Are the Signs and Symptoms of Anal Abscess?

The perianal abscess often appears as painful boil-like swelling near the anus. It is red and warm to the touch. The perianal abscess can occur superficially or deep. Pain in the perianal area is the most common finding.

Superficial anal abscesses are associated with:

• Constant throbbing pain, which gets worse when sitting down.

• Swelling, redness, tenderness, and skin irritation around the anus.

• Pus discharge.

• Rectal bleeding.

• Difficulty in urination.

• Constipation or pain during bowel movements.

• The infant may be fussy and irritable.

Deep anal abscesses are less common and may be less visible. Deeper anal abscesses are associated with:

• Fever.

• Chills.

• Malaise.

How Can We Diagnose Anal Abscesses?

Physical examination, including a digital rectal exam, is the primary method to diagnose anal abscesses. A Laboratory blood test usually reveals an elevated white blood cell count. Anoscope is used to look into the anal canal and rectum. Colonoscopy is used in patients with Crohn's disease. A flexible tube with a light is used to examine the large intestine and colon.

Some additional tests are done to screen for the following diseases:

• Sexually transmitted infections.

• Inflammatory bowel disease.

• Rectal cancer.

Magnetic resonance imaging (MRI), computed tomography (CT) scan, and ultrasound are sometimes needed.

What Is the Treatment of Perianal Abscesses?

Surgical incision and drainage of the perianal abscesses are the most common treatment and should be done before the abscess rupture. Surgical drainage has a higher success rate. The abscess sometimes can drain pus on its own and heal without the need for any other treatment. Do not pop or try to drain out the abscess on your own.

A superficial anal abscess is drained using a local anesthetic (1 % Lidocaine) in a doctor's office. Before the local anesthetic injection, Ethylene chloride spray is used to numb the area. Deeper anal abscesses require hospitalization and general anesthesia. Drained abscesses are usually left open and do not require stitches.

Medications are given for pain relief. After the surgical drainage, antibiotics are prescribed for patients with diabetes and immunocompromised patients. Antibiotics are not necessary for healthy adult patients. Patients are advised to use a sitz bath (soak the affected area in warm water) three to four times daily.

Avoid heavy lifting or exercise one week after surgery. It takes about two to three weeks to heal completely. Stool softeners are recommended to reduce the discomfort of bowel movements. Fiber supplements are given to avoid constipation. Some patients are advised to use a gauze pad to prevent the drainage from spoiling the clothes. Appropriate treatment should be done for the associated disorders like diabetes and inflammatory bowel disease.

Complications after the surgery include:

• Infection.

• Anal fissure.

• Scarring.

• A recurrent abscess.

• Anal Fistula: In one-third of the patients, an anal fistula is found either during or after abscess drainage. An anal fistula is a tunnel that forms from the anal canal to the skin near the anus. The American Society of Colon and Rectal Surgeons says that about 50 % of people with abscesses may develop anal fistula, which requires surgery.

An untreated anal abscess can spread to other body parts such as the groin and rectal lumen.

Regular follow-ups should be done until complete healing since the abscesses can recur.

How Are Perianal Abscesses Prevented?

• Take measures to protect from sexually transmitted infections.

• Get treated for conditions like Crohn's disease.

• Maintain good hygiene in the anal area.

• Clean the anal area and change the diaper frequently in infants and toddlers. In adults, use condoms during anal intercourse. These measures can prevent anal abscesses.

What Is the Differential Diagnosis of a Perianal Abscess?

The differential diagnosis for a perianal abscess includes:

• Hemorrhoids - Also known as piles (swollen veins in the anus and rectum).

• Anal Trauma - Injury to the tissues of the anus.

• Anal Fissure - Small tear in the lining of the anus.

• Anal Fistula - It is an abnormal connection from the anal canal to the skin near the anus.

• Buttocks Abscess - Boil on buttocks.

• Cellulitis - Serious bacterial skin infection.

• Crohn's Disease - It is a chronic inflammatory disease affecting the lining of the digestive tract.

• Ulcerative Colitis - It is a chronic inflammatory bowel disease that causes inflammation in the digestive tract.

• Malignancy.

• Acquired immunodeficiency syndrome (AIDS) and other sexually transmitted diseases.

Conclusion:

With proper treatment, patients with anal abscesses respond well. Infants and toddlers have a quick recovery. Complications occur when the treatment is delayed, but even then, it is treatable. Understanding the risk factors and treating them at the earliest can prevent anal abscesses.