ConditionDigestive system
Perianal Abscess
A perianal abscess is a collection of pus next to the anus, usually caused by an infected anal gland. It causes constant, throbbing pain that worsens when sitting, along with a red, hot, tender lump and sometimes fever. It does not go away with antibiotics alone: the standard treatment is incision and drainage, which brings rapid relief. About a third to a half of people later develop an anal fistula, a tunnel between the anal canal and the skin.
Also called: Anal abscess, anorectal abscess, perirectal abscess
At a glance
- What it is
- A pus collection beside the anus, usually from a blocked, infected anal gland.
- Symptoms
- Throbbing pain worse when sitting, a tender red lump, swelling, fever, pus drainage.
- Risk factors
- Crohn's disease, diabetes, weakened immunity, anal sex, constipation or diarrhea.
- Treatment
- Incision and drainage; antibiotics in some cases.
- After drainage
- Sitz baths, pain relief, fiber; healing in 3 to 4 weeks.
- Complication
- Anal fistula in roughly a third to half of people.
When to get help
Call 911 or go to the ER
- Rapidly spreading redness, swelling or dark skin of the buttocks, groin, perineum or genitals with severe pain and feeling very unwell (possible necrotizing infection)
- High fever, chills, confusion or fast heartbeat with anal pain (possible sepsis)
- Unable to pass urine with severe pain in the perineum
See a doctor within a day or two
- Constant throbbing pain near the anus with a hot, tender lump, worse when sitting (same-day care)
- Anal pain with fever
- A painful anal lump in someone with diabetes, Crohn's disease, HIV or on chemotherapy
Book a routine appointment
- Recurrent drainage of pus or blood from an opening near the anus after an abscess (possible fistula)
- Repeated abscesses
What causes a perianal abscess
The anal canal contains small glands that open into it. If a gland becomes blocked, bacteria from the bowel can multiply and form an abscess. The abscess tracks to the skin near the anus (perianal) or deeper into the surrounding tissues (ischiorectal, intersphincteric or supralevator abscesses).
Risk factors include:
- Crohn's disease and other inflammatory bowel disease
- diabetes
- weakened immunity: HIV, chemotherapy, steroids
- constipation or diarrhea
- anal sex
- anal fissures
- previous abscesses
Men are affected about twice as often as women, most often between ages 20 and 60.
Symptoms
- constant, throbbing pain near the anus, worse when sitting, coughing or having a bowel movement
- a red, hot, tender swelling or lump at the edge of the anus
- fever, chills and feeling unwell
- pus or blood draining if it bursts, with sudden pain relief
- deeper abscesses may cause rectal pressure and fever without a visible lump
- pain or difficulty passing urine
Perianal abscess vs other anal lumps
| Condition | Pain | Appearance |
|---|---|---|
| Perianal abscess | Constant, throbbing, increasing | Red, hot, tender swelling; may have fever |
| Thrombosed hemorrhoid | Sudden, severe, peaks in 48 to 72 hours | Firm blue-purple lump, not hot |
| Anal fissure | Sharp, tearing with bowel movements | Small tear, maybe a skin tag |
| Pilonidal cyst | Throbbing | In the cleft above the anus, not at the anus |
| Hidradenitis suppurativa | Recurrent tender lumps | Multiple lumps, scarring, also armpits and groin |
Diagnosis
Most perianal abscesses are diagnosed by examination. Deeper abscesses or those with unusual features may need:
- a rectal exam, sometimes under anesthesia
- MRI or endoanal ultrasound to map deep abscesses and fistulas
- CT for suspected deep or spreading infection
- blood tests and blood sugar
- colonoscopy if Crohn's disease is suspected
Treatment
Incision and drainage
The abscess is opened and drained, usually under local anesthesia in the office or ER for simple perianal abscesses, or under general anesthesia for deeper ones. Pain eases quickly once the pus is released. The wound is left open to drain, sometimes with a small drain or packing.
Antibiotics
Antibiotics are not a substitute for drainage. They are added for people with diabetes, weak immunity, heart valve disease, spreading cellulitis or signs of systemic infection.
Home care after drainage
- Sitz baths: sit in warm water for 10 to 15 minutes 2 to 3 times a day and after bowel movements.
- Pain relief: acetaminophen (paracetamol) or ibuprofen at the label dose.
- Soft stools: fiber, fluids and a stool softener to avoid straining.
- Gauze pads to absorb drainage.
- Follow-up to make sure healing is complete.
Most wounds heal in 3 to 4 weeks.
Complications
- Anal fistula: an abnormal tunnel from inside the anal canal to the skin, causing recurring discharge, irritation and abscesses. It usually needs surgery (fistulotomy, seton placement or sphincter-preserving procedures).
- Recurrence of the abscess.
- Spreading infection, including rare but life-threatening necrotizing infection (Fournier gangrene).
- Incontinence, rarely, after extensive surgery.
Prevention
There is no sure way to prevent a perianal abscess, but you can lower risk by:
- treating constipation and diarrhea
- managing Crohn's disease and diabetes
- good anal hygiene
- using condoms during anal sex to reduce the risk of infections
Frequently asked questions
What are the symptoms of a perianal abscess?
Symptoms include constant, throbbing pain near the anus that worsens when sitting, a red, hot, tender lump, swelling, fever and sometimes pus drainage. Deeper abscesses may cause rectal pressure and fever without a visible lump.
Can a perianal abscess go away on its own?
Sometimes an abscess bursts and drains on its own, which eases pain, but it often returns or forms a fistula. Antibiotics alone rarely cure it. Incision and drainage by a doctor is the recommended treatment.
How is a perianal abscess drained?
A doctor numbs the area with local anesthetic, makes a small cut over the abscess and lets the pus drain. Deeper abscesses are drained in an operating room under general anesthesia. The wound is left open to heal from the inside out.
How long does it take to recover from a perianal abscess?
Pain usually improves within a day or two of drainage. The wound generally heals in 3 to 4 weeks with sitz baths, good hygiene and soft stools. Ongoing drainage after this time may mean a fistula has formed.
Is a perianal abscess a sign of Crohn's disease?
It can be. People with Crohn's disease are more likely to develop perianal abscesses and fistulas, especially complex or recurrent ones. Your doctor may recommend tests for Crohn's disease if you have recurrent abscesses or other bowel symptoms.
Sources
This guide was written from current patient and clinical guidance, including:
- American Society of Colon and Rectal Surgeons (ASCRS): Clinical practice guideline for the management of anorectal abscess, fistula-in-ano and rectovaginal fistula
- MedlinePlus: Anorectal abscess
- NHS: Anal abscess
- Cleveland Clinic: Anal abscess
- American Gastroenterological Association: Perianal Crohn's disease