Anorectal abscess is a painful condition in which pus collects in a cavity like space near the anus or rectal region. The patient complains of severe pain, fever, and rectal pus discharge. Sometimes anal abscess does not heal and breaks open the skin to form communication between pus containing cavity and skin. This tunnel-like communication is called an anal fistula. Surgery is always required to treat anal fistula.
Causes of Anorectal Abscess
An anorectal abscess can have different causes like
- Blocked anal gland: It is the most common cause. There are several anal glands present around the anus. They secrete mucus to ease defecation. The stool material accidentally enters the gland blocking its drainage. Soon the gland becomes infected and converts to an abscess.
- An anal fissure: A tear in the anal canal which get infected.
- Sexually transmitted infections
Risk factors of Anorectal Abscess
These are the risk factors of having an anorectal abscess
- Gender: Males have two times higher chance than women of having an anorectal abscess
- Age: Incidence is highest in the third to the fifth decade of life.
- Immunocompromised state: people suffering from HIV or on medication like steroids or prednisolone
- Inflammatory bowel diseases like Crohn’s or ulcerative colitis
- Anal intercourse
- Toddlers and children that have a history of anal fissure
Symptoms of Anorectal Abscess
Pain and fever are the most common symptoms of anal abscess
- Pain: Pain is constant, throbbing, and present around the anus (perianal). It becomes worse after sitting down
- Fever with or without chills
- Swelling, redness, or tenderness around the anus
- Discharge of pus or blood from the abscess
- Constipation due to painful bowel movements
- Difficulty in urination
For abscess which is deeply seated, that is a deep anorectal abscess, some patients complain only of fever.
Diagnosis of Anorectal Abscess
Your doctor will ask you some question related to your medical history, conduct a physical exam and medical test to find the cause of your constipation
- Medical history: Your doctor will ask you many questions related to Your bowel habits: frequency, the color of stools, consistency, time of onset of problem, pain or blood during passing stools.
- Perform rectal exam: To see the fissure your doctor can use an anoscope which is a metallic hollow short tube inserted in the anal canal. The location of the fissure sometimes helps to find out the cause of anal fissure
- Endoscopy: In some people, it is difficult to diagnose externally due to the absence of superficial signs and symptoms. So, your doctor can insert a flexible tube is known as an endoscope with an attached camera and light to look inside the anal canal and lower rectum.
- Imaging test: These are used when the abscess is deep-seated and not visible even through the endoscope
- Ultrasound uses high-frequency soundwaves to generate images. It is a cheap and safe test.
- MRI – It uses a high magnetic field to create 3D images of the tissue.
- Additional tests: These additional tests may consist of blood or other imaging tests. Since, there can be other conditions contributing to the anal abscess your doctor can perform the additional tests for the screening of these conditions like Inflammatory bowel disease like Crohn’s or Ulcerative colitis, Sexually transmitted infections.
Treatment of Anorectal Abscess
Treatment is definitely required for anorectal abscess, without treatment there are high chances of complications like anal fistula. According to the American Society of Colon and Rectal Surgery (ASCRS), about 50% of anal abscesses get converted to the anal fistula. Anal fistula always requires surgery. So, the treatment of abscess consists of
- Drainage: The most common and simple treatment for an abscess is to drain it. For superficial abscess, it can be done in a single day but for deeper abscess hospitalization is required.
- Medication: Meanwhile your doctor can prescribe you medications for pain relief or antibiotic if there is an infection or the person is immunocompromised or suffering from diabetes.
- Surgery: For large and complicated abscess or those which recur again despite of treatment, surgery is the final option. The chances of an abscess to appear again are rare after surgery. After completion of the surgery, the patient is advised to sit in a warm water tub (sitz bath) for 15 to 20 minutes, at least three times a day.
Prognosis of Anorectal Abscess
Your surgeon will advise you proper post-surgical care. Sometimes despite of complete healing and proper care, the abscess can come back. It indicates that fistula is present and it needs to be treated by surgery.