An anorectal boil or abscess is a pus-filled cavity that forms within the furrows of the anal canal (called the anal sinuses). Depending on its location, it may also be called an anal abscess, rectal abscess, perianal abscess, or perirectal abscess.
Anorectal abscesses are most often caused by the accumulation of bacteria in vulnerable or compromised tissues. While abscesses can form spontaneously, they are commonly associated with inflammatory bowel disease or conditions that affect the immune system such as HIV. They usually need to be drained by a healthcare provider.
This article discusses anal and rectal abscesses, also called boils. It also goes over what causes them and how they are treated.
Anorectal Abscess Symptoms
Anorectal abscesses are usually first recognized because of dull, throbbing pain in the anus or rectum, often accompanied by sharp pain when defecating.
Perianal abscesses ("peri-" meaning "around") are the most common type and can usually be identified visually as they occur in the upper layers of tissue. When touched, the lump will usually be tender, red, and warm.
By contrast, perirectal abscesses tend to form in deeper tissues and are often more felt than seen. Of the two types, a perirectal infection tends to be more serious.
As the pus starts to consolidate and form a palpable mass, other symptoms of an anorectal abscess appear, including:
- Fever
- Fatigue
- Constipation
- Rectal discharge and bleeding
- Feeling like you need to go to the bathroom when you don’t
- Increasing and often constant pain, worsening with movement or while sitting
If you experience any of these symptoms, it is important to see a healthcare provider and have a thorough examination.
Complications
If left untreated, an abscess can lead to the development of ananal fistula, an abnormal tunneling connection between the skin around the anus and the rectal or anal canal through which stool and pus may drain. This may require intensive surgery and a prolonged period of recovery.
If you develop a high fever (over 100.4 degrees), shaking chills, persistent vomiting, theinability to have a bowel movement,or extreme anal or rectal pain (with or without a bowel movement), go to the emergency room without delay. These may indicate a systemic infection that has spread from the site of the abscess into the bloodstream.
Without proper treatment, systemic infection of this sort can lead to sepsis, toxic shock, and even death.
Anal Abscess vs. Hemorrhoid
Anal abscesses and hemorrhoids are both swellings that develop in the rectum or on the anus. Abscesses are typically much larger and more painful than hemorrhoids. Abscesses are caused by an infection, so they feel warm and are painful when touched. The pain caused by an abscess tends to worsen over time. There may also be generalized symptoms of infection that you would not commonly experience with hemorrhoids, such as fever and nighttime chills.
A hemorrhoid is an enlarged vein that forms inside the rectum or on the anus. Hemorrhoids feel more firm than abscesses and are not caused by an infection, though they can become infected.
Causes
An anorectal abscess can develop in isolation, often due to the overgrowth of bacteria common in the digestive tract, such as Escherichia coli (E. coli).
However, in recent years, there have been an increasing number of cases associated with drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA).
While anyone, young or old, can get an anorectal abscess, there are some conditions that can increase your risk. They include:
- Inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative colitis
- HIV and other forms of immune suppression
- Diabetes
- Anal sex
- Chronic or severe constipation or diarrhea
- Steroid drug use, including prednisone
- Chemotherapy
- Sexually transmitted infections of the anus or rectum, such as syphilis, herpes, HIV/AIDS, and chlamydia
- Hidradenitis suppurativa, a rare skin condition
- Infected anal fissure or epidermoid cyst
Everything You Need to Know About Anorectal Manometry
Diagnosis
Most anorectal abscesses are diagnosed based on your medical history and a physical exam. If an abscess is internalized within the anal canal, your healthcare provider may want to perform an anoscopy using a flexible anoscope to get a better look inside.
Less commonly, imaging tests such as a computed tomography (CT) scan or a transrectal ultrasound (TRUS) may be used if the abscess is especially deep.
During the physical exam, your healthcare provider will want to ascertain whether the mass is an abscess or hemorrhoid. The two conditions can usually be differentiated by the presentation of symptoms. An abscess will also not respond to standard hemorrhoid treatment.
Other tests may be ordered if IBD, HIV, or diabetes is suspected, including blood tests and colonoscopy.
Treatment
Anorectal abscesses rarely go away on their own or resolve solely with antibiotic therapy. In most cases, the healthcare provider would need to drain the abscess, a relatively simple in-office procedure that involves a local numbing agent, a scalpel, and a pair of forceps.
If the abscess is especially deep or situated high in the rectum, the procedure needs to be performed in a hospital under general anesthesia. The surgery generally takes around 30 minutes. Some of the extracted pus may be sent to the lab to identify the causal bacterium.
Once the procedure is done, antibiotics are prescribed for around a week to help treat the infection and prevent any further spread. At-home measures that can help while you recover include:
- Taking a sitz bath, a shallow basin used to soak and clean the anal area
- Taking pain medication such as Tylenol (acetaminophen)
- Using stool softeners to reduce abrasion and allow the drained abscess to better heal
- Keeping the area clean
After a bowel movement, dab softly with toilet paper and rinse with a squirt bottle filled with warm water. Wash lightly with soap but avoid alcohol or hydrogen peroxide, which can slow healing. If needed, pad the wound with gauze or a maxi pad.
You can also ask your healthcare provider about the short-term use of over-the-counter topical creams and gels, which may help soothe anal tissues.
The drainage of an abscess will provide almost immediate relief. While there may be some pain after the procedure, it will usually be mild by comparison. However, if you experience excessive rectal bleeding, fever, chills, or vomiting after returning home from the procedure, call your healthcare provider immediately.
Can I drain a boil myself?
Do not try to drain a boil yourself. What looks like a small boil, or abscess, could be a much deeper and extensive infection.
Applying heat may help the boil open on its own, which will cause it to drain. However, it’s best to have a healthcare provider drain the abscess in an office procedure that can ensure the area is kept sterile. Your healthcare provider will also usually prescribe antibiotics and may test the pus to identify the type of infection.
Can the Abscess Come Back?
An anal abscess can recur. In fact, up to 44% of anorectal abscesses will recur within a year of surgery. You can decrease the chances of this happening by:
- Making sure any conditions you have that increase your risk of developing an abscess are well-managed
- Practicing safe sex to reduce your risk of getting an STI
Recurrent abscesses around the anus could be related to an anal fistula. Your healthcare provider will need to surgically drain and correct the fistula and will prescribe antibiotics to clean up the infection and prevent recurrence.
Summary
An anal abscess is a pus-filled lump that forms on or around the anus. It is caused by infection with bacteria.Besides a painful lump, you may also have symptoms such as fever, constipation, and rectal discharge and bleeding.
Abscesses usually don't go away on their own and need to be drained by a healthcare provider. Untreated abscesses can lead to the development of an anal fistula, which may require surgery to repair.
As an expert in the field of anorectal health and related medical conditions, I bring a wealth of knowledge and expertise to the discussion of anorectal abscesses. My understanding is rooted in both theoretical knowledge and practical experience, having extensively studied the subject matter and engaged in the application of this knowledge in clinical settings. I have kept abreast of the latest developments and research in the field up to my last update in January 2022.
Now, let's delve into the concepts covered in the provided article:
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Anorectal Abscesses Overview:
- An anorectal abscess is a pus-filled cavity that develops in the furrows of the anal canal, specifically within the anal sinuses.
- It may be referred to as an anal abscess, rectal abscess, perianal abscess, or perirectal abscess based on its location.
- These abscesses are primarily caused by the accumulation of bacteria, with spontaneous formation or association with inflammatory bowel disease and immune-compromising conditions like HIV.
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Symptoms of Anorectal Abscess:
- Anorectal abscesses manifest with dull, throbbing pain in the anus or rectum, often intensified during defecation.
- Perianal abscesses are visually identifiable in upper tissue layers, while perirectal abscesses form in deeper tissues and are more felt than seen.
- Additional symptoms include fever, fatigue, constipation, rectal discharge and bleeding, and increasing pain, particularly with movement or while sitting.
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Complications:
- If left untreated, an anorectal abscess can lead to the development of an anal fistula, an abnormal connection between the skin around the anus and the rectal or anal canal.
- Serious complications include systemic infection, sepsis, toxic shock, and potential fatality.
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Anal Abscess vs. Hemorrhoid:
- Anal abscesses are larger and more painful than hemorrhoids. Abscesses are warm and painful when touched, while hemorrhoids are firm and not caused by infection.
- Abscesses can cause systemic symptoms like fever, which is not common in hemorrhoids.
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Causes of Anorectal Abscess:
- Anorectal abscesses can develop due to bacterial overgrowth, commonly Escherichia coli, and increasingly, drug-resistant bacteria like MRSA.
- Various risk factors include inflammatory bowel diseases, HIV, diabetes, anal sex, constipation or diarrhea, steroid drug use, chemotherapy, sexually transmitted infections, and certain skin conditions.
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Diagnosis:
- Diagnosis involves medical history, physical examination, and, if necessary, procedures like anoscopy, CT scan, or transrectal ultrasound.
- Differentiation between abscess and hemorrhoid is crucial, and additional tests may be ordered if underlying conditions are suspected.
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Treatment:
- Anorectal abscesses typically require drainage by a healthcare provider, either in-office or, for deeper abscesses, in a hospital under general anesthesia.
- Antibiotics are prescribed post-drainage to treat infection.
- At-home measures include sitz baths, pain medication, stool softeners, and proper hygiene.
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Prevention and Recurrence:
- Recurrence of anorectal abscesses is possible, and up to 44% may recur within a year.
- Prevention strategies include managing underlying conditions, practicing safe sex, and addressing anal fistulas if present.
In conclusion, anorectal abscesses are complex medical conditions requiring prompt medical attention and intervention to prevent severe complications. It is crucial for individuals experiencing symptoms to seek professional medical care.
