Anal fistula (or perianal) is a small canal that develops between the end of the intestine (known as the anal canal) and the skin near the anus.

Some types of fistula are formed by only one channel, while others have at least two tunnels. The ends of the fistula can appear as holes in the surface of the skin around the anus.

An anal fistula is painful and can cause bleeding when you go to the bathroom.
Some fistulas can be attached to the sphincter muscles (those that open and close the anus).

Anal fistula can also affect children.



Fistula intersphincteric
The channel begins in the space between the muscles of the internal and external sphincter and ends very close to the anal opening.

Transsphincteric fistula
The stretch begins in the space between the muscles of the internal and external sphincter or in the space behind the anus. It then traverses the external anal sphincter and ends within a few centimeters of the anal opening.

This can take the form of a U, with openings on both outer sides of the anus (is called a horseshoe fistula).

Supra-sphincteric fistula
The canal begins in the space between the internal and external sphincter muscles and follows upwardly from the pubortal muscle through this muscle, then extends downward between the pubortalis muscle and the anus lifter.
Thus it opens a few cm of the anus.

Extra-systolic fistula
The canal begins in the rectum or sigmoid colon and extends down through the anus lifter and opens around the anus.
Generally, these fistulas are caused by an appendiceal abscess, diverticular abscess or Crohn’s disease .

Causes of anal fistula

An anal fistula is often the result of a previous or current anal abscess, it can occur in 50% of abscessed patients.
An anal abscess is an infected cavity filled with pus near the anus or rectum.

The normal anatomy of the rectum includes small glands just inside the anus.
Rarely can these glands block and potentially infect causing an abscess.
The fistula is a tunnel that forms under the skin and connected the glands infected with the abscess. A fistula may be present with or without an abscess.

Rarely, fistulas can be caused by other diseases, such as

The symptoms of an anal fistula are:

  • Irritation of the skin around the anus,
  • A  pain  that can aggravate while remaining seated, moving and during evacuation,
  • Loss of pus or blood during defecation,

If the fistula was caused by an abscess still present, you may notice:

If the fistula was caused by inflammation of the bowel, for example because of an illness such as irritable bowel syndrome or ulcerative colitis , you may have other symptoms, such as:

Diagnosis of anal fistula

Knowing the full course of an anal fistula is important for effective treatment. The opening of the outside usually appears as a red and inflamed area that can perspire, pus and blood.
This external aperture is usually easily seen.
Finding the opening in the anus (inner end) is more complicated.

The latest technologies are as follows:

Endoscopic ultrasound uses high-frequency sound waves to produce detailed images of sphincter muscles and other structures in the pelvic floor.

Other options include:

  1. Anoscope , a small endoscope used to visualize the anal canal.
  2. Sigmoidoscopy , a procedure to exclude other diseases such as ulcerative colitis and Crohn’s disease.
  3. fistulograph is an obsolete technique, it is an x-ray of the fistula after the injection of a contrast solution.
  4. The MRI can be used for fistulas that are very hard to find.


How to do anal fistula surgery?

  1. Fistulotomy – A hysterectomy is an outpatient procedure performed under general or spinal anesthesia .
    The insertion of a probe through the fistula or tunnel canal. Then the surgeon makes an incision along the fistula and performs a procedure to eliminate all cells from the fistula.
    The skin edges are sewn together so they can not reconnect and rebuild the tunnel or fistula. Scar tissue fills the void of the fistula. Fistulotomies are made for fistulas that are not too deep and do not need a large muscle incision.
    After surgery, your doctor may advise you to take antibiotics for a few days to prevent infection.
  2. The position of the seton – if during the passage of a probe through the tunnel is seen that the amount of sphincter muscle being cut to open the fistula cause fecal incontinence, the surgeon may decide to spend a silk tie or synthetic sterile tissue called seton through the canal and tie it to the skin.
    This elevates the treatment of the fistula out of the body and the seton falls.
    Fortunately, the muscle does not break completely and so if the muscle ring is intact it retains the ability to hold the stool.
  3. Endorectal flap – the endorectal flap was originally designed to treat fistulae between the rectum and the vagina in order to avoid a temporary colostomy and allow healing.
    With this technique, the surgeon closes the exposure to the rectum and anal canal by attacking a bandage the tongue shape by dissecting the mucosa, submucosa and a small amount of muscle over the rectal fistula. The tip of the flap attached to the opening of the internal fistula is surgically removed.
    The muscular bore is identified and sewn with some absorbable stitches.
    Then the surgeon attaches the flap over this area only repaired with absorbable sutures.
    This technique has a success rate of about 75%. Usually an overnight stay in the hospital.
  4. Intervention with collagen . Several devices have been studied to allow the mechanism of natural healing of the body and to close the fistula.
    Among these are collagen buffers and other absorbable materials.
    When used alone or in combination with fibrin glue, its success rate is less than 30%. However, in combination with an endorectal flap, this technique can help cure complex or recurrent fistulas.
  5. LIFT Procedure – Means tying the interphincteric fistula. This technique is performed on an outpatient basis under general anesthesia or the spinal, if an incision is made just outside the anus.
    Dissection is performed between the anal sphincter muscles (internal and external) and the fistula channel is identified.
    They bind with dissolvable sutures at both ends and are sewn along the extracted part.
    The incision is closed by draining and can put a sheet of biological material to help prevent recurrence of the fistula.
    The success rate varies between 40 and 75% with this technique
  6. The VAAFT technique is used for the surgical treatment of complex anal fistulas.
    The strengths of this technique are the exact location of the fistula, the treatment of the internal and the hermetic seal of the internal opening.
    They avoid surgical wounds in the perianal region and the risk of fecal incontinence because they do not cause damage to the anal sphincter.

What to expect after surgery for  anal fistula

It is necessary to rest until the anesthetic effect is over.
It can serve as an anti-inflammatory or analgesic when the anesthetic effect disappears.
It is normal to notice a slight bleeding, a blood stain on the medication or the toilet paper for several days after the operation.
The surgeon gives instructions on how to take care of the surgical wound.
The nurse will change the dressing every day until needed.

Recovery and course after surgery for  anal fistula

To reduce pain, you can take over-the-counter anti-inflammatories like paracetamol or ibuprofen.
General anesthesia temporarily affects coordination, motor and mental abilities, and then you should not drive, drink alcohol, use machines, or sign documents within the next 24 hours.
After the operation, we recommend a diet to prevent constipation that can cause excessive abdominal contraction, when you go to the bathroom and can apply a lot of strain on the walls of the anus.

What are the alternatives for surgery?

Surgery is the main treatment for anal fistulas, but there is also the option with fibrin glue.
Spontaneous healing can occur in the case of a simple perianal fistula, but it is very rare.
An untreated anal fistula can expand, in addition the substances can also be stored (blood, feces, urine, etc.) and can cause an infection .

Non-surgical treatment of anal fistula

glue Fibrin glue is currently the non-surgical option for the treatment of fistulas. The fibrin glue is injected into the fistula to seal the canal. The glue is inserted through the opening of the fistula which then closes with a seam.
Fibrin glue may seem like an attractive option as it is simple, safe and painless. However, the long-term results for this method of treatment are scarce.
For example, a small study had an initial success rate of 77%, but after 16 months, only 14% of people are cured.

Prognosis of anal fistula

Wound healing times are six weeks.
It may be helpful to apply an absorbent to prevent wound loss from staining clothing.
You can go to the bathroom with the bandage in place, but make sure that the washing is accurate you need to dry the anal area well afterwards.
Do not stand for long periods or do not walk much. Follow the advice of the surgeon.

The length of hospital stay depends on the severity of the fistula, if it is mild, the doctor can sign your resignation on the same day, while in severe cases you may need to be hospitalized for a few days.


Are Anal Fistulas Dangerous? What are the risks?

Anal fistula operations are performed frequently and usually there are no problems. However, in order to make a decision and give consent, you should be aware of possible side effects and risks of complications.

Side effects of anal fistula

Side effects and unwanted effects are mostly temporary immediately after surgery. At first you may feel pain, especially when sitting. You may also notice slight bleeding.

Complications of anal fistula

Specific complications of anal fistula are rare but include:

  • Infection can cause anal abscess and then need another surgery.
  • Damage to the sphincter muscles – both the fistula and the procedure used to treat it can damage and weaken the sphincter, this can affect bowel control and can cause fecal incontinence.
  • Narrowing of the anal canal (the muscular tube that connects the rectum), which can cause difficulty in emptying the bowel.
  • Recurrent fistula – it is possible that the fistula is formed again.

The risks are different for each patient, ask the surgeon the personal risks.

Read too: