What is a perianal fistula?

A perianal fistula is an abnormal tunnel that forms between the anal canal and the skin around the anus. It often develops after an anal abscess, which is a pocket of infection and pus near the anus. When the abscess drains, it can leave behind a small tunnel that continues to leak fluid or pus. The NHS describes an anal fistula as a small tunnel between the end of the bowel and the skin near the anus, usually caused by an infection near the anus.

A perianal fistula may cause ongoing discomfort, drainage, swelling, irritation, and repeated infections. It usually does not heal well on its own and often needs medical treatment.

How do I know if I have a fistula?

You may suspect a fistula if you have repeated pain, swelling, or discharge around the anus. Some people notice a small opening or “hole” near the anus that drains pus, blood, stool-like fluid, or foul-smelling fluid.

Possible signs include:

• A small opening near the anus
• Ongoing drainage
• Pain while sitting
• Swelling near the anus
• Redness or tenderness
• Recurrent abscesses
• Skin irritation
• Fever if infection is active

Mayo Clinic lists an opening on the skin around the anus, redness, oozing of pus, blood or stool, rectal or anal pain, and fever as possible symptoms.

Are fistulas painful?

Yes, fistulas can be painful, but the level of pain varies. Some people feel mild irritation or pressure, while others experience severe throbbing pain, especially if the fistula becomes blocked or infected.

Pain may worsen during:

• Sitting
• Walking
• Bowel movements
• Coughing
• Physical activity
• Abscess formation

The pain may temporarily improve if pus drains from the fistula, but the underlying tunnel often remains.

What does a perianal fistula look like?

A perianal fistula may look like a small hole, pit, bump, or opening near the anus. The surrounding skin may appear red, swollen, irritated, or tender. Some fistulas drain pus, blood, mucus, or stool-like fluid.

It may appear as:

• A tiny opening near the anus
• A red or inflamed spot
• A draining sore
• A swollen painful lump
• A recurring abscess-like bump

The appearance can vary depending on the fistula’s depth, location, and whether infection is present.

Why do I have two holes in my anus?

If you notice what seems like two holes near the anus, one may be the normal anal opening and the other may be an abnormal fistula opening. A fistula can create a second external opening on the skin where fluid drains from an internal tunnel.

However, not every extra opening or skin change is a fistula. It could also be related to a healed abscess, skin tag, cyst, fissure, pilonidal disease, or another skin condition. A healthcare professional can examine the area and confirm the cause.

Is a small hole near the anus always a fistula?

No, a small hole near the anus is not always a fistula. While a fistula is one possible cause, other conditions can look similar.

Possible causes include:

• Anal fistula
• Draining abscess
• Skin lesion
• Pilonidal sinus
• Enlarged pore or cyst
• Skin tear
• Healed wound
• Hidradenitis suppurativa

Because the treatment differs depending on the cause, a proper diagnosis is important.

What are the symptoms of a perianal fistula?

Symptoms of a perianal fistula usually involve pain, drainage, and irritation around the anus. The symptoms may come and go, especially if the fistula repeatedly drains and then becomes blocked again.

Common symptoms include:

• Anal pain
• Swelling around the anus
• Redness or tenderness
• Pus or blood drainage
• Foul-smelling discharge
• Skin irritation
• Itching
• Fever if an abscess is present
• Recurrent anal abscesses
• Difficulty controlling bowel movements in some cases

NHS Wales lists skin irritation, constant throbbing pain, smelly discharge, pus or blood, swelling, fever with abscess, and difficulty controlling bowel movements as possible symptoms.

How is a perianal fistula diagnosed?

A perianal fistula is usually diagnosed through a medical history and physical examination. A doctor may inspect the area around the anus to look for an external opening, drainage, swelling, or signs of abscess.

Diagnostic methods may include:

• Physical examination
• Digital rectal exam
• Anoscopy
• MRI scan
• Endoanal ultrasound
• CT scan in selected cases
• Examination under anesthesia
• Tests for Crohn’s disease if suspected

Imaging is especially helpful for complex fistulas because it shows the path of the fistula tract and whether it involves the anal sphincter muscles.

What are the treatment options for perianal fistulas?

Treatment depends on the fistula’s location, complexity, infection status, and whether it involves the anal sphincter muscles. Simple fistulas may be treated differently from complex fistulas, especially when preserving bowel control is a concern.

Treatment options may include:

• Antibiotics if infection is present
• Pain management
• Abscess drainage
• Fistulotomy
• Seton placement
• Fibrin glue
• Advancement flap procedure
• LIFT procedure
• Treatment for Crohn’s disease if related

Mayo Clinic lists fistulotomy, seton placement, fibrin glue, and other surgical approaches among treatment options for anal fistula.

Can a perianal fistula heal on its own?

A perianal fistula usually does not heal on its own. It may drain and feel better temporarily, but the tunnel often remains and can become infected again. The NHS states that anal fistulas will not usually get better on their own and that surgery is commonly recommended.

Without treatment, a fistula may lead to:

• Recurrent abscesses
• Persistent drainage
• Skin irritation
• Chronic pain
• Spread of infection
• More complex fistula tracts

Early treatment can reduce the risk of complications and repeated infections.

What is a fistula cyst?

A “fistula cyst” is not always a precise medical term, but people may use it to describe a lump, fluid-filled pocket, or cyst-like swelling along a fistula tract. In many cases, this may actually be an abscess, blocked drainage pocket, or inflamed tissue connected to the fistula.

A cyst-like fistula swelling may cause:

• Pain
• Pressure
• Redness
• Drainage
• Swelling near the anus
• Recurrent tenderness

If a lump becomes painful, warm, swollen, or associated with fever, it may be an abscess and should be evaluated promptly.

How do you manage perianal fistula pain?

Pain management depends on whether there is active infection or abscess formation. Home care may help mild discomfort, but it does not cure the fistula itself.

Helpful comfort measures may include:

• Warm sitz baths
• Over-the-counter pain relievers if suitable
• Keeping the area clean and dry
• Wearing breathable underwear
• Avoiding prolonged sitting
• Using soft wipes or gentle cleansing
• Treating constipation to reduce straining

If pain becomes severe, throbbing, or is associated with fever or swelling, medical care is important because this may suggest an abscess.

What is anal leakage, and is it related to fistula discharge?

Anal leakage means fluid, mucus, stool, or discharge leaks from the anus or nearby skin involuntarily. It can happen for several reasons, including diarrhea, weak sphincter muscles, nerve problems, hemorrhoids, inflammatory bowel disease, or fistula discharge.

Fistula-related leakage may involve:

• Pus
• Blood
• Mucus
• Foul-smelling fluid
• Stool-like discharge in some cases

A fistula can irritate the skin and cause ongoing wetness or staining of underwear. If leakage is persistent, foul-smelling, bloody, or associated with pain, a colorectal specialist should evaluate it.