What is Anorectal Fistula?
An anal fistula is a condition caused by blocked and infected glands in the anal area, resulting in an abscess or collection of pus. Even after the abscess drains, there is a chance that a fistula may form. Fistulas can greatly disturb patients and reduce their quality of life. There are four types of anorectal fistulas: transsphincteric, high intersphincteric, suprasphincteric, and extrasphincteric. Treatment for each type varies, with fistulotomy or fistulectomy being common for some types and seton placement being necessary for others. St James University Hospital provides an imaging-based classification system for fistulas, which helps in preoperative assessment. The severity of the fistula determines the appropriate treatment approach.
What Causes Anorectal Fistula?
Fistulas can be caused by several reasons, known as “FRIEND”. This stands for foreign body, radiation, infection or Inflammatory Bowel Disease, epithelialization, neoplasm, and distal obstruction. Foreign bodies and radiation can cause fistulas. Infections, particularly in the anal region, are the most common cause. Understanding the anatomy of the area is important for surgical management. Fistulas can also be a symptom of anal tuberculosis or sexually transmitted infections. Radiation proctitis and complicated vaginal births can also lead to fistulas. Preserving the function of the external sphincter is important for bowel continence.
Risk Factors and Frequency for Anorectal Fistula
An anorectal fistula is not very common, with only 1 to 8 cases for every 10,000 people per year. In western countries, up to a quarter of these cases are linked to Crohn’s disease. This condition is twice as likely to occur in males and typically appears in people aged between 30 and 50.
- Risk factors for developing an anorectal fistula include obesity, diabetes, high blood fat levels, history of anorectal surgery, and high salt intake.
- Smoking can also contribute to the development and recurrence of anorectal fistulas or associated abscesses.
- People who are under 40 or who have recurrent anal abscesses may be more likely to develop an anorectal fistula.
Signs and Symptoms of Anorectal Fistula
To diagnose a perirectal abscess, doctors need to know the patient’s medical history, including general health and sexual history. Patients with inflammatory bowel disease may have tenderness during a physical exam and may have symptoms such as bloody diarrhea, abdominal pain, weight loss, or fever. Cancer or pelvic radiation therapy can cause a fistula, so treatment will need to be discussed with a cancer specialist. Syphilis or tuberculosis could also be causes of a fistula. Common complaints from patients with a fistula include itching, drainage, discomfort, and pain when passing stool. Previous abscesses or anorectal procedures can also contribute to the development of a fistula. Doctors will perform a perianal exam and anoscopy to evaluate the issue, looking for external openings, drainage, and swollen tissue. Anesthesia may be needed to find the internal opening of the fistula. The location of the opening can determine the path of the fistula. Patients may experience irritation from constant drainage, leading to the need for frequent pad changes.
Testing for Anorectal Fistula
Imaging studies, such as endo-anal ultrasound, CT scans, CT-fistulography, and MRI, are helpful for diagnosing and understanding an anorectal fistula. Endo-anal ultrasound is a cost-effective option for patients with chronic fistulas, while CT scans are useful in emergency situations. CT-fistulography is a good outpatient tool for identifying fistula tracts. MRI is the most effective for identifying fistulous tracts and planning treatment. Basic laboratory tests should also be done to check for other conditions.
Treatment Options for Anorectal Fistula
Treatment options for anorectal fistula depend on the cause. Initial exams involve anesthesia and identifying the fistula tract. A fistulotomy, opening the fistula, is effective for acute anal fistulas. Fistulectomy with sphincter reconstruction is used for more complex cases. Seton placement allows the fistula to drain and heal. Ligation of the intersphincteric fistula tract ties off the fistula, but recurrence rates are high. Advancement flap covers the internal fistula opening. Anal fistula plugs can be used, but outcomes vary. Video-assisted anal fistula treatment visualizes and treats the fistula. Seton placement is common for patients with Crohn’s disease.
What else can Anorectal Fistula be?
When diagnosing an anal fistula, doctors must consider other conditions that could cause similar symptoms. These conditions commonly seen in general or colorectal surgery practices include:
- Anal fissure (a small tear in the lining of the anus)
- Anal warts
- Hemorrhoids (swollen veins in the lower part of the anus and rectum)
- Perianal abscess (a pocket of pus near the anus)
- Solitary rectal ulcer syndrome (a condition that causes rectal bleeding and straining)
Doctors also need to consider other conditions that may mimic an anal fistula. These include:
- Crohn’s disease (an inflammatory bowel disease)
- Hidradenitis suppurativa (a skin condition causing lump-like scars often around the groin and armpits)
- Anal cancer
- Sexually transmitted diseases such as syphilis, herpes, gonorrhea, and chlamydia can present symptoms similar to a fistula
- In patients with HIV, symptoms of an anal fistula might indicate the presence of certain types of cancer such as Kaposi’s sarcoma or lymphoma.
It’s essential for healthcare providers to consider all these possibilities and conduct necessary tests to identify the correct diagnosis.
What to expect with Anorectal Fistula
The outlook for anorectal fistula, an abnormal connection between the anal region and the skin near the anus, varies depending on the cause. Healing rates after surgery range from 60% to 80% for different types of fistulas. Setons have a success rate of 80% to 90% within six months. If a fistula doesn’t heal or returns after surgery, it may be due to incomplete operation, flap failure, or premature removal of setons. Recurrent fistulas may require further procedures, such as another LIFT procedure, flap advancement, or seton usage. VAAFT, a minimally invasive surgery, can be used as a last resort if other treatments fail.
Possible Complications When Diagnosed with Anorectal Fistula
The complications that might arise after anal fistula surgery include:
- Recurrence of fistula
- Loss of control over gas or stool (incontinence)
- Persistent draining wound
- Narrowing of the anus (anal stricture)
There are certain factors that can increase the risk of the anal fistula returning after surgery. These include complex anal fistulas such as high transanal fistula, horseshoe extensions, and multiple fistula tracts. A history of anal procedures and a failure to identify the internal opening of the fistula during surgery also contribute to this risk.
In addition, there are specific factors that increase the risk of fecal incontinence after surgery for anal fistula. These include a history of anorectal procedures, female gender, complex fistulas and incontinence before the operation. Surgeons avoid performing fistulotomy (surgical opening of the fistula) in certain high risk cases to reduce the chance of postoperative incontinence. Anal manometry, a test to assess the functionality of the anal sphincter muscles, can help identify patients who should have a more conservative surgical approach.
Women are more likely to experience fecal incontinence after surgery. If incontinence of gas or stool occurs, treatments can include biofeedback therapy, sacral nerve stimulation, or more invasive treatments. These could range from surgical tightening of the muscle (sphincteroplasty), the placement of a magnetic anal sphincter or implantation of an artificial anal sphincter. In cases where non-invasive and invasive options have all been attempted without success, a colostomy might be considered.
Prevention is the best way to avoid any complication. One way to prevent incontinence is to minimize the number of procedures a patient needs for his or her fistula and to specifically tailor therapy for patients at high risk. It is beneficial to have a conversation with patients about the risks of fecal incontinence before surgery and also conduct preoperative anal manometry. Obtaining a detailed preoperative image to identify the type of fistula before surgery should also be considered.
Preventing Anorectal Fistula
Anal abscesses are fairly common, and in about 40% of cases, they can lead to a condition called anal fistula. Most of these fistulas originate from a type of infection linked to the glands around the anus. By preventing anal abscesses, the occurrence of anal fistulas can also be reduced.
One common prevention strategy involves educating patients on the benefits of a healthy diet and regular exercise, which can help guard against diabetes – a risk factor for anal abscess. In addition, safe sex education, particularly in the gay community, is essential as sexually transmitted infections affecting the anal area can contribute to the development of anal fistulas.
It’s also important to make people aware of the early symptoms of Crohn’s disease such as weight loss, stomach pain, bloody stools, and symptoms affecting other body parts. Recognizing and diagnosing Crohn’s disease early can help manage the condition better and reduce the discomfort and problems associated with anal fistulas in patients with this disease.
Improving access to medical care can also help prevent anal abscess-related complications. This is because untreated abscesses are more likely to develop into fistulas. Furthermore, teaching patients about good hygiene practices in the anal area, such as bathing daily and keeping the area clean, can also help prevent these challenging conditions.
