What Will Happen If a Fistula Is Left Untreated? Understanding the Risks

September 30, 2025 •

5 min read

An anal fistula will not heal on its own and almost always requires medical or surgical treatment to resolve completely. Therefore, understanding what will happen if a fistula is left untreated is crucial for anyone experiencing its symptoms, as ignoring the condition can lead to a host of escalating and serious complications.

Quick Summary

Untreated fistulas can cause chronic and worsening symptoms like pain and foul-smelling drainage, escalating into more severe health problems such as recurrent abscesses, complex tracts, and potentially life-threatening systemic infection.

Key Points

Recurrent Infections: An untreated fistula leads to a cycle of persistent and recurring infections and abscesses due to the open tract constantly draining bacteria.
Increased Complexity: Delaying treatment can cause a simple fistula to branch into multiple complex tracts, making future surgical repair significantly more challenging and invasive.
Risk of Incontinence: Chronic inflammation and sphincter muscle damage from an untreated fistula can lead to fecal incontinence, severely impacting quality of life.
Danger of Sepsis: In rare but critical cases, the infection can enter the bloodstream and cause life-threatening sepsis, a medical emergency.
Scarring and Stricture: Long-term inflammation leads to scarring and narrowing of the anal canal, causing painful bowel movements and constipation.
Requires Medical Intervention: Fistulas do not heal on their own and require surgical intervention to properly close the tract and resolve the underlying issue.

Understanding a Fistula

A fistula is an abnormal tunnel or passageway that forms between two organs or between an organ and the surface of the skin. While fistulas can occur in many parts of the body, the most common type is an anal or perianal fistula. This occurs when an abscess (a pus-filled pocket) near the anus fails to heal correctly, leaving a persistent tract that connects the inside of the anal canal to the skin outside.

Symptoms of a fistula typically include:

Persistent throbbing pain and swelling around the anus.
Foul-smelling, bloody, or pus-like discharge from a skin opening near the anus.
Itching, soreness, or redness around the anal opening.
Fever, chills, and fatigue, especially if an infection flares up.

Without treatment, these symptoms will not go away and will often worsen over time, as the fistula provides a pathway for bacteria to cause ongoing and recurring infections.

The Escalating Dangers of an Untreated Fistula

When a fistula is ignored, the body cannot heal it completely. The initial infection may subside temporarily, but the underlying tunnel remains open, leading to a cycle of recurring infections and abscesses. Each recurrence increases the risk of more severe, long-term complications. The longer the condition goes untreated, the more complex and difficult it becomes to manage.

Recurrent Infections and Abscesses

The most immediate consequence of an untreated fistula is the high probability of developing recurrent perianal abscesses. Bacteria from the rectum continuously travel through the fistula tract, causing repeated infections. Each new abscess can lead to increased pain, swelling, and systemic symptoms like fever and chills, significantly impacting quality of life.

Progression to Complex Fistula Tracts

Over time, a simple fistula can progress into a more complex network of tunnels. Chronic inflammation and infection can cause the tract to branch out in new directions and develop secondary openings. This makes surgical treatment considerably more challenging, potentially requiring multiple complex procedures and longer recovery periods.

Risk of Anal Sphincter Damage and Fecal Incontinence

Complex fistulas can cause significant damage to the anal sphincter muscles, which are crucial for controlling bowel movements. This can result in fecal incontinence, leading to an inability to control the passage of gas or stool. Fecal incontinence is a devastating complication that can severely affect a person's social life, mental health, and overall well-being. The risk of this damage is a primary reason why timely and careful surgical intervention is so critical.

Severe Scarring and Anal Stricture

Chronic inflammation and infection cause scarring of the surrounding tissues. This scarring can lead to a condition called anal stricture or stenosis, where the anal canal narrows. The narrowing makes passing stool difficult and painful, often leading to chronic constipation and further discomfort.

The Danger of Sepsis

In rare but serious cases, an untreated fistula infection can spread from the localized area to the bloodstream, causing a life-threatening condition called sepsis. Sepsis is a medical emergency that requires immediate treatment. It occurs when the body's immune response to an infection damages its own tissues and organs, and without quick intervention, it can lead to organ failure and death.

The Extremely Rare Risk of Cancer

While uncommon, there is a small risk that a chronic, untreated fistula that has persisted for many years could increase the chances of developing anal cancer. Long-term inflammation and tissue erosion are known risk factors for cancer development in any part of the body. This reinforces the need to address the condition early and effectively.

Untreated vs. Treated Fistula: A Comparison


Feature	Untreated Fistula	Treated Fistula (with surgical repair)
Symptom Resolution	Temporary relief, but symptoms almost always return.	Long-term relief and healing of the tract.
Recurrence	Highly likely, with recurring abscesses and infections.	Significantly reduced risk of recurrence, especially with proper care.
Tract Complexity	Simple tracts can become complex networks over time.	Treatment addresses the full tract, preventing complex progression.
Pain	Persistent, chronic pain and discomfort.	Managed pain during recovery, with resolution after healing.
Complications	Increased risk of sepsis, fecal incontinence, and stricture.	Minimalized risk of severe complications with specialized care.
Quality of Life	Severely impacted by chronic pain, discomfort, and uncertainty.	Restored quality of life once healing is complete.

The Necessity of Medical Intervention

A fistula is not a condition that will simply resolve itself over time. It is a persistent channel of infection that requires medical intervention to heal properly and prevent further complications. While some very rare cases might temporarily close, they often reopen later, restarting the cycle of discomfort.

Treatment almost always involves a surgical procedure to address the fistula tract. The type of surgery depends on the fistula's complexity and location. Common procedures include:

Fistulotomy: A procedure where the fistula tract is cut open, allowing it to heal from the inside out.
Seton Placement: A surgical thread is placed in the tract to help it drain and slowly cut through muscle over time.
Advancement Flap Procedure: A tissue flap is used to cover the internal opening of the fistula.
LIFT Procedure: A minimally invasive technique to ligate the tract between the sphincter muscles.
Fibrin Glue or Plug: Non-surgical options to seal the tract.

Your doctor, often a colorectal specialist, will perform a thorough examination, including imaging if necessary, to determine the best course of action. The National Institutes of Health (NIH) offers more in-depth information on fistula treatment.

Conclusion

Ignoring a fistula is not a viable long-term solution. The condition will inevitably worsen, progressing from a simple, painful nuisance to a complex and potentially dangerous health issue. The longer treatment is delayed, the more invasive and difficult the required procedures become, and the higher the risk of permanent complications like fecal incontinence or sepsis. Seeking timely medical attention is the only effective way to properly treat a fistula, alleviate persistent symptoms, and prevent the severe consequences of a chronic, untreated condition.

When to Act Immediately

If you experience any of the signs of an infected fistula, such as severe pain, high fever, or significant swelling, you should seek immediate medical attention. These could be indicators of a worsening infection that requires urgent care.

Frequently Asked Questions

No, an anal fistula will not heal on its own. While symptoms may temporarily subside, the underlying tract will remain, and the infection will almost certainly return, often with greater severity.

Worsening symptoms include an increase in pain and swelling around the anus, persistent and worsening foul-smelling discharge, or the onset of a fever and chills, which could indicate a spreading infection.

There is no safe duration for leaving a fistula untreated. The condition will not improve and will instead lead to a chronic, worsening cycle of pain, infection, and potential complications like abscesses and sphincter damage.

While not common, sepsis is a serious and possible complication of an untreated fistula. It occurs when the infection spreads into the bloodstream, requiring immediate medical attention.

In very rare cases, a chronic, untreated fistula that has existed for many years has been associated with an increased risk of anal cancer due to long-term inflammation. This is not a common outcome but is a potential long-term risk.

While both can cause anal pain, a fistula is characterized by a specific skin opening with continuous foul-smelling or pus-like discharge, and often involves fever. Hemorrhoids are swollen blood vessels and typically present with bright red blood and itching.

The primary treatment for a fistula is almost always surgery to address the underlying tract. Common procedures include fistulotomy, seton placement, or more complex procedures depending on the fistula's nature.