fistula, causes, symptoms, surgery and prognosis

An (or perianal) fistula is a small canal that develops between the end of the intestine (known as an canal) and the skin near the anus.
Some fistula species are formed by only one channel, while others have at least two tunnels. The ends of the fistula can appear as holes on the skin around the anus.

An fistula is painful and can cause bleeding when you go to the toilet.
Some fistulas may be connected to the sphincter muscles (which open and close the anus).



Intersphinctary fistula
The canal begins in the space between the inner and outer sphincter muscle and ends very close to the opening.

Transphinctary fistula
The tract begins in the space between the inner and outer sphincter muscle, or in the space behind the anus. Then he crosses the outer sphincter and ends a few centimeters next to the opening.
The fistula can take on a U-shape, with an external opening on either side of the anus (horseshoe fistula).

Supersphinctary fistula
The canal begins in the space between the inner and outer sphincter muscle and runs upwards over the puborectalis muscle (pubic-rectal muscle), passes through this muscle and then runs downwards between the puborectalis muscle and the levator ani muscle (lifter of the anus).
It then opens a few centimeters next to the anus.

Extrasphinctary fistula
The canal begins in the rectum or sigmoid colon and extends downwards, runs through the levator ani muscle and opens in the anus area.
Usually, these fistulas are caused by an appendix abscess, a diverticular abscess, or Crohn’s disease.

Causes of fistula

An fistula often results from a previous or current abscess and can form in 50% of patients with an abscess.
An abscess is an infected cavity full of pus near the anus or rectum (rectum).

The normal anatomy of the rectum has small glands in the anus right at the beginning.
Rarely, these glands can close off, potentially infect and cause an abscess. The fistula is a tunnel that forms under the skin and connects the infected glands to the abscess. A fistula can occur with or without an abscess.

Rarely, fistulas can be caused by other conditions, such as:

  • Crohn’s disease
  • sexually transmitted diseases
  • Tuberculosis
  • Cancer
  • Diverticulitis

Symptoms of fistula

  • Irritation of the skin around the anus
  • Pain that may worsen when sitting, bowel movements, or coughing
  • Discharge of pus and blood during defecation

If the fistula was caused by a still existing abscess, the following symptoms can be observed:

  • Fever of at least 38°C
  • Fatigue
  • general malaise

If the fistula was caused by inflammation of the intestine, for example due to a condition such as irritable bowel syndrome or ulcerative colitis, symptoms may occur, such as:

  • Abdominal pain
  • Diarrhea
  • Loss of appetite
  • Weight loss
  • Nausea (feeling malaise)
  • burning
  • Itching in the anus area
  • pain, for example when cycling
  • Vomit

Diagnosis of fistula

It is necessary to know the complete course of an fistula in order to be able to choose an effective therapy. The outer opening of the fistula canal usually appears reddened, is inflamed, and pus and blood may leak. This external opening is usually easy to recognize.

Finding the second opening in the anus area (internal end) is a bit more complicated.

The latest examination techniques are:

Echo-endoscopy, high-frequency sound waves are used to obtain detailed images of the sphincter and other structures of the pelvic floor.

Other possibilities:

Anoscope, a small endoscope to visualize the canal.

Sigmoidoscopy, a procedure to rule out other conditions such as ulcerative colitis and Crohn’s disease.

Fistulography is an outdated technique. This is an X-ray of the fistula after the injection of contrast medium.

Magnetic resonance imaging can be useful for fistulas that are very difficult to find.

How is the operation performed for fistula?

  1. Fistulotomy – A fistulotomy is an outpatient procedure performed under general anesthesia or spinal anesthesia.
    A probe is inserted into the canal or tunnel of the fistula. After that, the surgeon splits the entire fistula along the probe and leaves it to “open wound healing”, eliminating all cells of the fistula.
    The edges of the skin are sutured so that they cannot close and form a fistula or tunnel again. The scar tissue fills the emptiness of the fistula. Fistulotomies are performed on fistulas that are not very deep and do not require major muscular incisions.
    After surgery, the doctor may prescribe taking antibiotics for a few days to avoid infection.
  2. Positioning a sling – If, during probing the fistula tunnel, it is determined that the part of the sphincter to be severed would lead to fecal incontinence in order to open the fistula, the surgeon may decide to place a so-called seton, a sterile loop made of silk or synthetic fabric, through the fistula canal and tie it up at the level of the skin.
    The thread drainage exerts a pull on the surrounding tissue and thus allows the formation of fibrous tissue that closes the fistula.
    After that, the thread must be tightened every 2 weeks in practice to allow the sphincter muscle to form scar tissue.
    This leads to a slow lifting of the fistula outwards until the noose falls off.
    Fortunately, the muscle never splits completely, and with the muscle ring intact, it retains its ability to restrain the stool.
  1. Endorectal flap – The endorectal flap was originally developed to treat the fistulas between the rectum and vagina to avoid temporary colostomy and allow healing.
    In this technique, the surgeon closes the breakthrough to the rectum and canal by attaching a tongue-shaped flap by attaching mucosa and submucosa and a small muscle portion of the rectum above the fistula. The tip of the flap, which is attached to the inner fistula opening, is surgically removed.
    The muscle hole is identified and sutured with some self-decomposing threads.
    After that, the surgeon places the flap over the previously closed area and sutures it with self-decomposing threads.
    This technique has a success rate of about 75%. Usually you stay in the hospital for one night.
  1. Surgery with collagen-containing cone – In order to allow the body a natural healing process and close the fistula, various objects were examined.
    These include collagen cones and other absorbable materials. When used alone or in combination with fibrin glue, their success rate is less than 30%. However, this technique in combination with an endorectal advancement flap can promote the healing of complex or recurrent fistulas.
  1. LIFT technique – This means stopping the tract of the intersphincter fistula. This technique is performed in practice and under general or spinal anesthesia. The incision is made immediately outside the anus.
    The dissection is performed between the inner and outer sphincter and the fistula canal is determined.
    With self-decomposing threads, both ends are prevented and sewn along the removed part.
    The incision is closed, drainage is inserted, and a sheet of biological material can be inserted to prevent recurrence of the fistula.
    The success rate with this technique varies between 40 and 75%.
  2. The VAAFT technique is used in the surgical treatment of complex fistulas. Strengths of this technique are the exact position determination of the fistula, the treatment from the inside and the hermetic closure of the inner opening.
    Surgical wounds in the area and the risk of fecal incontinence are prevented, because no lesions are caused on the sphincter.

What to expect after fistula surgery?

It is necessary to rest until the effect of the anesthetic has worn off.
If the anesthetic wears off, an anti-inflammatory or painkiller may help.
There may be a slight bleeding or blood stain on the bandage or toilet paper a few days after surgery.
The surgeon gives instructions on how to treat the wound.
The nurse changes the bandage every day as long as it is necessary.

Recovery and postoperative course
To relieve the pain, over-the-counter anti-inflammatories such as acetaminophen or ibuprofen can be taken.
General anesthesia temporarily affects coordination and motor and mental ability. Therefore, for the next 24 hours, you are not allowed to drive, drink alcohol, operate machines or sign legal documents.

After surgery, a light diet is recommended to avoid constipation, which can lead to excessive abdominal contraction during bowel movements and put pressure on the walls.

What are the alternatives to surgery?

Surgical surgery is the primary treatment for fistulas, but there are also alternatives with fibrin glue.
Spontaneous healing can be done with a simple perianal fistula, but this is very rare.

An untreated fistula can spread and substances (blood, feces, urine, etc.) can settle that can cause an infection.

Non-surgical treatment of fistula

Fibrin glue
Fibrin glue is currently the non-surgical alternative for the treatment of fistulas. The fibrin glue is injected into the fistula to seal the canal. The fibrin glue is inserted through the fistula opening and then closed with a suture.
Fibrin glue can appear as an attractive option because it is a simple, safe and painless procedure. However, the long-term results for this treatment method are poor. For example, a small study showed an initial success rate of 77%, but after 16 months, only 14% of people were considered cured.

Prognosis for fistula

The healing time for the wound is six weeks.
It may be necessary to provide sanitary pads to avoid the wound discharge soiling the laundry.
You can go to the toilet with the bandage, but it must be ensured that it is cleaned accurately and the area is dried well.
You should not stand for long periods of time and do not walk too much. The surgeon’s advice should be followed.

Are fistulas dangerous? What are the risks?

Operations for fistula are often performed and usually do not cause any problems. But before a decision is made and consent is given, one should know all possible side effects and risks for complications.

Side effects of fistula surgery

Side effects and unwanted effects are usually temporary and occur immediately after the procedure. At the beginning there is pain, especially when sitting. Slight bleeding can also be observed.

Complications of fistula

Special complications of fistula are rare, but they include:

  • Infection – it can result from an abscess, so it requires further intervention.
  • Damage to the sphincter muscles – both the fistula and the treatment procedure can damage and weaken the sphincter. This can impair control over the intestines and lead to fecal incontinence.
  • Narrowing of the canal (muscle tube that connects the rectum to the anus), which could lead to difficulty emptying stools.
  • Fistula recurrence – it is possible that the fistula will recur.

The risks are different for each patient, personal risks can be found out from your surgeon.

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