How do I check if I have a fistula?

September 24, 2025 •

4 min read

According to the Crohn's & Colitis Foundation, approximately 30% of people with Crohn's disease will develop a fistula. If you are experiencing concerning symptoms, you may be asking, “How do I check if I have a fistula?” The key is to recognize the signs and seek a professional medical diagnosis.

Quick Summary

Recognizing the signs of a fistula involves observing persistent symptoms like pain, swelling, and abnormal drainage of pus, blood, or fluid from an opening near the anus or other affected areas. Since self-diagnosis is unreliable, a medical professional will need to perform a physical exam and other diagnostic tests, such as an MRI or ultrasound, to confirm a diagnosis and determine the best course of treatment.

Key Points

Look for telltale symptoms: Persistent pain, swelling, redness, and abnormal discharge of pus or fluid from an opening near the anus are common signs of a fistula.
Self-diagnosis is unreliable: Due to the internal nature of most fistulas, a physical exam and advanced imaging by a healthcare professional are essential for an accurate diagnosis.
A history of abscesses is a major clue: Recurrent anal abscesses that drain and then reappear strongly suggest an underlying fistula.
Location dictates symptoms: The type of fistula influences symptoms; a rectovaginal fistula, for example, might cause gas or stool to pass from the vagina.
Prompt medical attention is necessary: Early diagnosis and treatment can prevent the condition from worsening, reducing the risk of complications and leading to a better outcome.
Professional tests confirm the diagnosis: Your doctor may use an MRI, endoscopic ultrasound, or fistulography to visualize the fistula tract and plan treatment.

What is a Fistula?

A fistula is an abnormal connection or tunnel that forms between two organs, vessels, or between an organ and the skin. These passages can occur anywhere in the body but are most common in the digestive, urinary, and reproductive systems. They can arise from trauma, surgery, infection, or chronic inflammation, such as that caused by Crohn's disease. Symptoms vary greatly depending on the fistula's location and can range from mild discomfort to severe pain and infection.

Recognizing Common Symptoms

The signs and symptoms of a fistula depend heavily on its location. The most common type is an anal fistula, but they can occur in other areas as well. It's important to be aware of the specific symptoms for each type to help guide your conversation with a healthcare provider.

Anal Fistula Symptoms

Persistent Pain: A throbbing, continuous pain around the anus that worsens with sitting or during bowel movements is a common sign.
Swelling and Redness: Noticeable swelling, redness, and a tender lump near the anal opening are often present, indicating an infection.
Abnormal Drainage: A key indicator is the drainage of pus, blood, or foul-smelling fluid from an opening near the anus. This may cause itching and irritation of the surrounding skin.
Recurrent Abscesses: If you have a history of anal abscesses that drain and then reappear, it may be a sign of an underlying fistula.
Fever and Fatigue: In some cases, a fistula can be accompanied by a fever, chills, and a general feeling of being unwell.

Rectovaginal Fistula Symptoms

Gas or Stool from Vagina: The passage of gas or stool through the vagina is a definitive sign of a rectovaginal fistula.
Foul-Smelling Discharge: A persistent, foul-smelling vaginal discharge is common.
Urinary Tract Infections: Chronic, recurrent UTIs can sometimes indicate a fistula connecting the urinary tract.

The Professional Diagnostic Process

Attempting to check for a fistula at home is not recommended, as a medical diagnosis by a qualified healthcare provider is necessary to ensure accuracy and determine the appropriate treatment. Here is a look at the diagnostic process:

Initial Consultation and Physical Exam

Your doctor will begin by discussing your symptoms and medical history. During a physical exam, they will examine the affected area to look for signs of a fistula opening, redness, or swelling. For anal fistulas, a specialist may use an anoscope—a small instrument to view the anal canal.

Imaging and Diagnostic Tests

If a fistula is suspected, several tests can be performed to confirm the diagnosis, map the tract, and assess its complexity:

Fistulography: A contrast dye is injected into the external opening of the fistula and X-rays are taken to visualize the tunnel.
MRI (Magnetic Resonance Imaging): This advanced imaging technique provides detailed images of the fistula tract and its relationship to surrounding structures, including the sphincter muscles.
Endoscopic Ultrasound: High-frequency sound waves are used to create detailed images of the internal fistula and the surrounding tissues.
Colonoscopy or Sigmoidoscopy: If Crohn's disease is suspected as an underlying cause, these procedures may be used to examine the colon and rectum.
Examination Under Anesthesia: In some complex cases, a surgeon may need to perform a thorough examination of the fistula while the patient is under anesthesia to get a clear picture without causing pain.

Comparison of Diagnostic Methods


Diagnostic Method	Best For	Advantages	Disadvantages
Physical Exam	Initial assessment	Simple, non-invasive	May miss complex or internal fistulas
MRI	Complex fistulas	High-resolution images, shows sphincter involvement	Higher cost, not always necessary
Endoscopic Ultrasound	Perianal fistulas	Excellent visualization of soft tissues	Requires specialized equipment
Fistulography	Visible fistulas	Can map the path of the tract	May not show internal branches
Colonoscopy	Suspected Crohn's	Examines bowel for underlying disease	Invasive, requires prep

What to Do If You Suspect a Fistula

If you have any of the symptoms mentioned above, it is important to contact a healthcare provider for a proper evaluation. Ignoring these symptoms can lead to worsening infection, discomfort, and potentially more serious complications. Early diagnosis and treatment are crucial for the best outcome.

Preparing for Your Appointment

Keep a Symptom Log: Note when your symptoms started, how often they occur, and what makes them better or worse.
List Your Medical History: Be prepared to discuss past infections, surgeries, and any pre-existing conditions like Crohn's disease.
Ask Questions: Prepare a list of questions for your doctor to ensure you understand the diagnosis and treatment plan. For authoritative medical guidance, you can also consult resources like the Cleveland Clinic's section on fistulas: Fistula: Definition, Types & Causes.

Conclusion

While you cannot check for a fistula at home with certainty, recognizing the symptoms is the first critical step. A fistula is a serious medical condition that requires professional diagnosis and treatment. By consulting a healthcare provider and undergoing the appropriate tests, you can receive an accurate diagnosis and a treatment plan tailored to your specific needs, helping to alleviate discomfort and prevent complications.

Frequently Asked Questions

While a very small or simple fistula might close spontaneously, most anal fistulas do not heal without surgical intervention. Antibiotics may help with the infection but are not a cure for the fistula itself.

The most common type of fistula is an anal fistula, which connects the anal canal to the skin near the anus. It typically develops from an anal abscess, a pus-filled infection of an anal gland.

If you notice an opening near your anus, especially if it is accompanied by pain, swelling, or drainage, you should contact a healthcare provider, ideally a specialist in colon and rectal diseases, for an evaluation.

In some cases, fistulas are a complication of underlying conditions such as Crohn's disease or other inflammatory bowel diseases. A doctor may perform additional tests to rule out or diagnose these conditions.

An anal fistula may look like a small hole or opening in the skin near the anus that may ooze pus, blood, or other fluid. The surrounding skin may also be red and inflamed.

Treatment for a fistula almost always involves surgery. Options range from a simple fistulotomy for straightforward cases to more complex procedures like a LIFT procedure or the use of setons for more complicated fistulas.

Stress does not directly cause a fistula. However, stress can trigger flare-ups of inflammatory bowel diseases like Crohn's disease, which are a known risk factor for developing fistulas.