ANAL ABSCESS AND FISTULA
An
anal abscess is an infected cavity filled with pus near the anus or
rectum.
An
anal fistula (also called fistula-in-ano) is a small tunnel that tracks from an
opening inside the anal canal to an outside opening in the skin near the anus.
An anal fistula often results from a previous or current anal abscess. As many
as 50% of people with an abscess get a fistula. However, a fistula can
also occur without an abscess.
CAUSES
Small
glands just inside the anus are part of normal anatomy. If the glands in the
anus become clogged, this may result in an infection. When the infection is
serious, this often leads to an abscess. Bacteria, feces, or foreign matter can
also clog the anal glands and cause an abscess to form. Crohn’s disease,
cancer, trauma and radiation can increase the risk of infections and
fistulas.
SYMPTOMS
A
patient with an abscess may have pain, redness or swelling in the area
around the anal area or canal. Other common signs include feeling ill or tired,
fever and chills. Patients with fistulas have similar symptoms, as well as
drainage from an opening near the anus. A fistula is suspected if these
symptoms tend to keep coming back in the same area every few weeks.
DIAGNOSIS
Most
anal abscesses or fistulas are diagnosed and managed based on clinical
findings. Occasionally, imaging studies such as ultrasound, CT scan or MRI
can help in the diagnosis and management of deeper abscesses and may be used to
visualize the fistula tunnel.
TREATMENT
The
treatment of an abscess is surgical drainage under most circumstances. It
is important that your surgeon be very familiar with treating abscesses and
fistula. Colorectal surgeons are experts in this area. For most
patients, an abscess can be drained surgically through a simple procedure. An
incision is made in the skin near the anus to drain the infection. This can be
done at your surgeon’s office with local anesthetic or in an operating room
under general anesthesia. Some patients with more severe disease may require
multiple surgeries to take care of the problem. Patients who tend to get
more severe infections due to diabetes or immunity problems may need to be
hospitalized
Surgery
is nearly always needed to treat an anal fistula. In many patients, if the
fistula is not too deep, a fistulotomy is performed. During this surgery, the
fistula track will be opened to allow healing from the bottom up. The surgery
may require dividing a small portion of the sphincter muscle. A large amount of
the sphincter muscle is not divided as this could lead to problems with bowel
control (fecal incontinence) in some patients. If the fistula track does
involve a large portion of the sphincter muscle, other more involved
surgeries are done to treat the fistula without harming the sphincter muscle. More
difficult cases may require multiple surgeries.
Antibiotics
alone are not effective in treating abscesses or fistula. Antibiotics may be
needed, in addition to surgery, if a patient has immunity issues, specific
heart valve conditions or widespread cellulitis (a bacterial infection of
the skin and tissues under the skin). Providing your physician with an accurate
medical history and undergoing a physical exam are important steps in deciding
if antibiotics are required.
POST-TREATMENT PROGNOSIS
Your
surgeon will advise you on proper postsurgical care. Unfortunately, despite
proper treatment and complete healing, an abscess or a fistula can come
back. If an abscess comes back, it suggests that perhaps there is a
fistula that needs to be treated. If a fistula comes back, additional
surgery will likely be required to treat the problem.