Anal fistula

What is an anal fistula?

An anal fistula is an abnormal, inflammatory connection that forms between the anal canal and the skin.
In most cases, it develops as a result of an untreated anal abscess.
The abscess is caused by an infection, which is often caused by a blockage of the anal canal glands.
The formation of a fistula allows secretions such as pus, blood and inflammatory tissue to escape from the internal fistula tract to the outside.
This can lead to persistent inflammation and pain.

There are various types of anal fistulas, which differ in their location and course:

• Inter-sphincteric fistulaThis fistula runs between the internal and external sphincter muscle and is the most common form.
• Trans-sphincteric fistulaThis fistula crosses both the internal and external sphincter and usually requires more complex treatment. – Extra-sphincteric fistulaThis runs above the sphincter muscles and often has a protracted and complex course.
  It can be caused by a more serious infection, such as in patients with Crohn’s disease.

The development of an anal fistula can take months or even years.
It often goes unnoticed for a long time, especially if it starts with a small, superficial abscess.
Without adequate treatment, however, a complex system of fistulous tracts can develop, making treatment difficult.

Anatomical basics

Understanding the anatomical structures around the anal canal is crucial to understanding anal fistulas.
The anal canal is lined with glands that are responsible for regulating moisture and protecting the anal canal.
If one of these glands becomes infected or blocked, an abscess can develop, which can be seen in the

In the worst case, this can lead to a fistula.
As the anal canal is surrounded by several layers of muscles, particularly the internal and external sphincters, the course of the fistula can run through or around these muscles.

Causes and risk factors

The development of anal fistulas can be favored by various factors and pre-existing conditions.
In most cases, the cause is a bacterial infection that leads to an anal abscess.
If such an abscess is not treated in time, a fistula develops from the accumulation of pus and inflamed tissue.
However, there are also a number of other causes and risk factors:

Primary causes

1. Anal abscessesThe most common cause of anal fistulas.
   These occur when the anal glands become infected by bacteria.
   If the abscess spreads into the deeper tissue layers of the anal canal, fistula formation can occur.
2. Chronic inflammatory bowel disease (IBD)Diseases such as Crohn’s disease and ulcerative colitis are often associated with the formation of anal fistulas.
   In patients with Crohn’s disease, up to 30% of those affected develop perianal fistulas, as the deep tissue inflammation damages the mucous membrane of the intestine and anal canal.
3. Anal infectionsInfections caused by sexually transmitted diseases, such as chlamydia or syphilis, can also lead to damage to the anal canal and promote the development of a fistula.

Secondary causes and risk factors

• Traumatic injuriesSurgical interventions or injuries to the anal area can lead to the formation of fistulas.
  A post-operative abscess, for example, can turn into an anal fistula.
• Immunosuppressive conditionsPatients with a weakened immune system, such as those with HIV or after an organ transplant, have an increased risk of developing an infection that can lead to fistula formation.
• Genetic predispositionThere is evidence that genetic factors may play a role in the development of anal fistulas, particularly in patients with chronic inflammatory bowel disease.

Symptoms and complaints

The symptoms of anal fistula vary depending on the severity and course of the disease.
While some patients have only mild symptoms, others suffer from chronic pain and recurrent infections.
The most common symptoms include

1. Pain in the anal areaThese typically occur when sitting, walking or during bowel movements.
   The pain can be acute or dull and often intensifies during bowel movements.
2. Secretion of pus or bloodA characteristic sign of an anal fistula is the discharge of pus or blood from an opening in the skin near the anus.
   This discharge may be intermittent and lead to unpleasant odors.
3. Swelling and rednessInflammatory swelling or redness in the anal area indicates an active infection or abscess.
4. Itching and irritationThe constant secretion of pus and fluid can cause skin irritation and severe itching.
5. Occasional fever and general feeling of illnessIn the case of severe or chronic inflammation, fever, chills and a general feeling of illness may occur.

Many patients report a constant, unpleasant feeling of pressure in the anal area caused by the inflammation and swelling.
This discomfort can become chronic if the fistula is not treated.

Diagnosis of an anal fistula

The diagnosis of an anal fistula begins with a thorough medical history and physical examination by a specialist in proctology.
The doctor will examine the anal area and look for signs of external opening of the fistula or inflammatory processes.
Since anal fistulas often run deep in the tissue, additional diagnostic measures are required to determine the exact course of the fistula.

1. clinical examination

During the physical examination, the doctor will look for visible signs of a fistula.
This may be a small opening near the anus that is leaking pus or fluid.
The doctor will often palpate the fistula tract to determine if there is a connection to the anal canal.

2. imaging procedures

As many fistulas have complex courses, imaging procedures are essential to determine the exact location and course of the fistula.

• Endoanal ultrasoundUltrasound provides detailed information about the course of the fistula in relation to the sphincter muscles.
  This method is particularly useful to determine whether the fistula crosses the sphincter and which surgical method should be considered.
• Magnetic resonance imaging (MRI)MRI is the most precise imaging technique for mapping the course of the fistula, especially in complex or extra-sphincteric fistulas.
  It allows the doctor to visualize the entire fistula tract and any secondary fistulas.
• Contrast fistulographyIn rare cases, a contrast agent is injected into the fistula to make the course of the fistula visible on an X-ray.
  This is mainly used for very deep fistulas.

3. fistula probing

In some cases, the doctor may insert a probe into the fistula tract during a short operation to check its course.
This method is usually used in conjunction with surgical treatment to fully open and treat the fistula.

Treatment options

The treatment of anal fistulas depends on the type and severity of the fistula.
While smaller and simple fistulas can often be treated conservatively, more complicated or deeper fistulas require surgical intervention.
There are various approaches that can be used both conservatively and surgically.

1. conservative therapy approaches

In some cases, anal fistulas can be treated conservatively, especially if the fistula is small and does not cause severe discomfort:

• Change of dietA high-fiber diet can soften the stool and reduce the strain on the anal canal, leading to symptom relief.
• Topical applications and sitz bathsSitz baths with antiseptic or anti-inflammatory additives can help to relieve symptoms and reduce inflammation.
• Antibiotics and painkillersIn the case of acute inflammation or infection, antibiotics can be administered to bring the infection under control.

2. surgical procedures

However, most anal fistulas require surgical treatment to completely remove the fistula and promote the healing process.
The most common procedures include:

• FistulotomyThis is the most commonly performed operation for simple fistulas.
  The fistula tract is split and left open to heal from the inside out.
  This method is particularly effective for simple, inter-sphincteric fistulas.
• Seton methodFor complex or trans-sphincteric fistulas, a seton (an elastic suture) is passed through the fistula tract to allow continuous drainage and promote healing.
  The seton can either be left loose or slowly pulled tighter to gradually close the fistula tract.
• Advancement flap processThis technique involves removing the fistula and closing the opening with a healthy flap of tissue.
  This method is particularly suitable for complex fistulas or those that cross the sphincter muscle, as it protects the integrity of the sphincter muscles.
• VAAFT (Video-Assisted Anal Fistula Treatment)This is a minimally invasive method in which a camera is inserted into the fistula tract to visualize the fistula tract.

from the inside and treat it with a special instrument.
The advantage of this method is that it is very precise and gentle on the tissue.

3. modern technologies

In addition to the classic surgical procedures, there are also innovative, minimally invasive techniques that are used in the treatment of anal fistulas:

• Laser therapyThis method uses a laser to close the fistula tract from the inside.
  The advantage of this method is that it is minimally invasive and heals more quickly.
• Stem cell therapyIn modern fistula treatment, stem cells are increasingly being used to promote tissue healing and reduce the risk of recurrence.
  This method is mainly used in patients with chronic inflammatory bowel disease.

Risks and complications

Although surgical treatment of anal fistulas is successful in most cases, some risks and complications can occur.
The most common include:

• Postoperative incontinenceIn some patients, especially if the fistula traverses the external sphincter, damage to the sphincter may occur, which in rare cases can lead to fecal incontinence.
• RecurrencesOne of the biggest challenges in the treatment of anal fistulas is the risk of recurrence.
  Even after successful surgery, fistula recurrence can occur in some cases, especially if the fistula is complex or has not been completely removed.
• Wound healing disordersIn rare cases, delayed or impaired wound healing may occur, especially in patients with a weakened immune system or chronic inflammatory diseases.

Prognosis and prospects of recovery

The prognosis after treatment of an anal fistula is generally good, especially if the fistula is diagnosed and treated early.
For simple fistulas that have been treated surgically, the healing rate is over 90%.
Most patients can resume their normal activities after a few weeks.
However, the chances of recovery depend greatly on the treatment method chosen and the complexity of the fistula.

In patients with chronic inflammatory bowel disease or complex fistulas, the prognosis may be less favorable and there is a higher risk of recurrence.
Regular follow-up and monitoring by the attending physician are essential in these cases to prevent recurrence.

Prevention of anal fistulas

Preventing anal fistulas starts with avoiding anal abscesses and other inflammatory processes in the anal area.
Here are some measures that can reduce the risk of fistula formation:

1. High fiber dietA diet rich in fiber promotes healthy digestion and reduces the risk of constipation, which can lead to increased pressure in the anal canal.
2. Adequate fluid intakeAdequate fluid intake keeps the stool soft and facilitates bowel movements, which reduces pressure on the anal canal.
3. Regular exercisePhysical activity promotes blood circulation throughout the body, including the anal area, and can therefore support the health of the anal glands.
4. Good hygieneRegular and gentle cleaning of the anal area can reduce the risk of infection and resulting fistula formation.

Patients with chronic inflammatory bowel disease should pay particular attention to the care of their anal area and visit their doctor regularly in order to recognize and treat inflammation at an early stage.

Anal fistula and related diseases

Anal fistulas often occur in conjunction with other proctologic diseases.
It is important to know the differences between these diseases to ensure correct diagnosis and treatment:

• HemorrhoidsAlthough hemorrhoids and anal fistulas can cause similar symptoms such as pain and bleeding, they are two different conditions.
  Hemorrhoids are swollen blood vessels in the anal area, while anal fistulas are inflammatory connections.
  However, both conditions can occur at the same time and require specific treatment.
• Anal abscessesAn anal abscess is the most common cause of an anal fistula.
  While the abscess is an accumulation of pus in the tissue, the fistula is the permanent channel that forms as a result of the abscess.
  It is important to treat an abscess in time to prevent the formation of a fistula.
• Crohn’s diseasePatients with Crohn’s disease have an increased risk of developing anal fistulas due to the deep tissue inflammation associated with this chronic bowel disease.
  Treatment of fistulas in Crohn’s disease often requires specialized anti-inflammatory therapies to control the underlying disease.

Conclusion

Anal fistulas are a painful and distressing condition that requires careful diagnosis and targeted treatment.
Thanks to modern medical

technologies and surgical procedures, however, the chances of recovery are good for most patients.
Early diagnosis and treatment are the key to successful healing and avoiding complications.
Patients should consult a proctology specialist at the first sign of an anal fistula to ensure timely treatment.
With a healthy lifestyle and regular medical check-ups, most patients can minimize the risk of developing an anal fistula.