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Anal Fistula Treatment

The goals of treatment for a perianal fistula are the complete closure of the fistula, the elimination of sepsis (if present), the prevention of recurrence, and continence (continued ability to control bowel movements). Combined medical and surgical treatments are used to treat perianal fistulas.

Having a multidisciplinary team which includes a gastroenterologist, radiologist, and colorectal surgeon is important. The treatment and management of perianal fistulas requires precise diagnostics to understand the disease, the correct choice of treatment option, either pharmacological or surgical, or both, as well as a monitoring plan to ensure they do not recur. There are many options and open and honest discussions between the healthcare team and the patient are extremely important.

Types of Anal Fistula Treatment


Antibiotics may be necessary in the treatment of anal fistulas as they are effective for improving symptoms; however, they rarely heal the fistula on their own. If there are septic symptoms present, they will generally be prescribed, usually a combination of ciprofloxacin and metronidazole. If severely septic, Amoxicillin-clavulanate, or even parenteral imipenem or piperacillin-tazobactam may be used.

Surgical procedures for perianal fistulas

Most with perianal fistulas will need surgery.  This is to drain the abscess causing the fistula. A colorectal surgeon will make an incision in the skin at one end of the fistula to drain the infection. This can be done either in the surgeon’s office with local anesthesia or in the operating room under general anesthesia. In some cases, it may take several surgeries to completely take care of the problem.

Other procedures include:

  1. Fistulotomy: If the fistula is too deep for a simple drainage, the fistula track will be opened to allow healing from the bottom up. The surgeon will cut the internal opening of the fistula, clean the infected area, and then flatten the tunnel and stitch it in place. This type of surgery may require cutting into the sphincter muscle. If the fistula tunnel involves a large portion of the sphincter muscle, other surgeries may be considered in order to minimize injury to the sphincter muscle which controls continence.
  2. Seton drain placement. This procedure places a surgical thread into the fistula in order to keep it open and drain the discharge. The surgeon may remove the drain and close the fistula with a fistulotomy or another procedure once the fistula has healed. However, if the fistula is caused by a chronic condition, it may be left in.
  3. Ligation of the intersphincteric fistula tract (LIFT). This procedure is designed to avoid cutting the sphincter muscle entirely by accessing the fistula between the sphincter muscles and avoid cutting them. This procedure usually follows a seton drain procedure described above. With this procedure, after the seton drain is removed, the surgeon closes, likely with stiches, the part of the fistula between the sphincter muscles.
  4. Endorectal advancement flap: This procedure is used to reduce the amount of sphincter muscle that is cut by the surgery. In this procedure, the infected tissue around the inside opening of the fistula is removed. A healthy piece of tissue (flap) from the inside of your rectum is cut and the opening of the fistula is covered with it. The fistula should continue to drain and heal from the inside out.
  5. Endoscopic ablation: In this procedure, endoscope (a long, thin tube with a small camera on the end) is put in the fistula. An electrode is then passed through the endoscope.  This electrode will cauterize the area it touches in the fistula tract.  The fistula tract is cauterized from the external opening to the internal opening through a series of electrodes.
  6. Fistulectomy: In this procedure, the surgeon completely removes the fistula tract. This procedure is rarely used as it increases the likelihood of damage to the anal sphincter muscles.  However, it may be necessary in some severe cases where the fistula interferes with normal bowel function, or if there is a high likelihood of recurrence.
  7. Filling the fistula with fibrin glue: This is one of two treatments that are non-surgical methods used to treat perianal fistulas without medication. While under general anesthesia, the surgeon cleans the fistula tunnel and then closes the internal opening with stiches. The fistula tunnel is then filled with a material, called fibrin glue, which is absorbed into the body while the fistula heals.
  8. Filling the fistula with a collagen plug. This is one of two treatments that are non-surgical methods used to treat perianal fistulas without medication. The surgeon cleans the fistula tunnel, and the fistula inner opening is then blocked with a plug of collagen protein.  This protein will provide a structure that allows for new tissue growth to close the internal opening of the fistula tract. 

Procedures for Anal fistulas are generally outpatient procedures and patients go home the same day without need for an overnight stay in the hospital. Pain medication is often prescribed following the procedure as the affected area will be sore and painful. Alongside the pain medications, some find taking a sitz bath (sitting in a warm bath) several times a day to be helpful. It will also aid in healing the area faster. The perianal area will likely have a wound dressing which will need to be changed often and kept clean.

Stages of Fistula Healing

Healthcare providers will use one of two categorizations when assessing fistulizing disease. During treatment, healthcare providers may assess the healing using the three stages of healing recognized in the fistula drainage assessment (FDA):

  • Draining: the presence of drainage containing, consisting of, or completely of pus after a gentle finger compression
  • Clinical Response: a reduction of 50% or more in the number of draining tunnels
  • Closed or remission: there is no pus drainage after compression. Remission is generally regarded as either the reduction or disappearance of the signs and symptoms of a disease.  A fistula assessed as closed or remission does not necessarily indicate the problem has fully been resolved.

Remission versus Response

Anal Fistulas are often a chronic condition for those with autoimmune diseases such as Crohn’s disease. When experiencing fistulas, it is not considered “cured” even if the treatment has proved successful. 

It is categorized as:

  • Symptomatic Response: Meaningful improvement in symptoms of pain and drainage in the absence of remission. This category is often used during treatment to assess if the current treatment is working.
  • Symptomatic Remission: The absence of both pain and drainage after gentle compression in the perianal area near the fistula opening.   
  • Complete Remission: the experience of being symptom-free or having a significant reduction in severity of symptoms following treatment. It does not; however. imply that the treatment has cured the disease or that another fistula will not develop. 
  • Radiographic Remission: The absence of inflammation in any fistula tract and the absence of any abscess. This is only confirmed by using either a pelvic MRI and/or endoanal ultrasound (EUS). (see below in diagnosis section)

Management of Crohn’s complex perianal fistulas (CPF)

There is one medication that can be used to treat Crohn’s complex perianal fistulas (CPF).  It is in a class called Biologic Therapies. These medications are antibodies created in a laboratory made from materials found in life, not a chemical compound used in pharmacology. Biologics stop certain proteins in the body from causing inflammation. There are also biosimilars, which are the generic form of the biologic they are the generic for.

Because biologics are made from living cells and organisms, they cannot be exactly reproduced like a chemical formula. Biosimilars are clinically similar to the biologic; but not exactly the same.  

Infliximab (Remicade®) is an intravenous infusion that has been approved by the FDA for the treatment and maintenance of remission of Crohn’s disease and ulcerative colitis. It is also approved for reducing the number of draining fistulas and maintaining fistula closure in adult patients with fistulizing disease.  There are three biosimilars for infliximab.  They are Infliximab-abda (Renflexis®), Infliximab-dyyb (InflectraTM) and Infliximab-qbtx (IXIFI™).

If infliximab is not available, another course of therapy is to treat the fistula and the underlying condition of Crohn’s disease at the same time. Healthcare providers will sometimes prescribe certain drugs to treat Crohn’s, beginning with milder ones and working up to more aggressive treatments. They will often use surgery alongside one of the following therapies.

  • Immunomodulatory agents:  Immunomodulators are medicines that modify the immune system, so it can work more effectively. Immunomodulators commonly used are azathioprine (Imuran®, Azasan®), 6-mercaptopurine (6-MP, Purinethol®), methotrexate, cyclosporine A (Sandimmune®, Neoral®) and tacrolimus (Prograf®). It can take up to three to six months to see an improvement in symptoms with immunomodulators; therefore, antibiotics and/or steroids may be used in the beginning.
  • 5-aminosalicylic acid (5-ASA): This anti-inflammatory medication is often prescribed to people with IBD to reduce inflammation in the digestive tract by working directly on the lining of the bowel. By reducing inflammation in the bowel, it is possible to achieve and maintain remission.
  • Corticosteroids: Sometimes a fast-acting anti-inflammatory steroid may be used. However, since long-term use can make IBD symptoms worse, they should only be used in the short-term to treat flares.
  • Biologic therapies: these biologics are used to treat Crohn’s disease, but do not treat perianal fistulas. In some cases, a combination of biologics may be used to achieve the best possibility for remission.
  • Anti-Tumor Necrosis Factor Agents (anti-TNF): This type of biologic helps reduce inflammation in the intestine as well as other organs and tissues. Adalimumab (Humira®) and Certolizumab pegol (Cimzia®). Both are given by injection (shot) to treat Crohn’s disease. There are three biosimlars for adalimumab.  They are Adalimumab-atto (Amjevita™), Adalimumab-adbm (Cyltezo™) and Adalimumab-adaz (HymirozTM).
  • Interleukin-12 and -23 Antagonist: This biologic helps to reduce inflammation. An example of this type of medication is Ustekinumab (Stelara®). The first dose of ustekinumab is given intravenously.  The remining treatments are given as an injection (shot).

Adapted from “Anal Fistulas: Treatment”- IFFGD Publication #145 by Satish Rao, MD, Harold Harrison, MD, Distinguished University Chair in Gastroenterology, Department of Gastroenterology/Hepatology, Augusta University, Augusta, Georgia

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