Perirectal (in ano) fistulas are an abnormal communication between the anal canal with the skin. In addition to the skin, the anorectal canal may communicate with adjacent organs. It is then possible to identify rectovaginal, rectovesical and retrourethral fistulas. They are usually caused by perianal abscesses, if they are left untreated. Other fistula causes include Cronh’s disease, ulcerative colitis, rectal cancer, tuberculosis and other infectious diseases.
Each fistula consists of an internal opening, a canal and one or two external openings.
Its clinical image includes a pus discharge and possibly dermatitis and itching in the affected area. Digital examination offers significant information in diagnosis.
Perianal fistulas are classified, depending on the tract of the canal and its relation to the inner sphincter are classified into intersphincteric, suprasphincteric, transsphincteric, and extrasphincteric. The tract of the canal is determined by means of fistulography, an examination where contrast medium is injected for medical imaging purposes. Intraoperatively, the tract of the canal is determined by the insertion of a special probe using special techniques by introducing methylene blue or hydrogen peroxide inside the fistula canal.
Perianal fistulas are surgically treated. There are various management techniques. In any case, the surgeon should be very familiar with the anatomy and physiology of the region and well-experienced in order to preserve sphincter integrity to prevent postoperative incontinence. It is necessary to identify the type and tract of the fistula canal and its relation to the adjacent anatomic structures.
A surgery method consists of laying open the fistula all along (fistulotomy) and excise the granular tissue to facilitate healing. Excision and complete removal of the fistula tract (fistulectomy) is the most radical method.
In high rectal or anorectal fistulas where the tract involves the sphincter a different technique is used. After removing the tract up the sphincter plane, a seton (a rubber band) or silastic vessel loop is passed through the fistula tract. Subsequently the loop is gradually tightened in the course of a few days until sphincter division due to pressure necrosis. Meanwhile fibrous tissue is formed averting the elimination of the divided muscle segments, preventing the occurrence of incontinence.
In cases of secondary fistulas the primary condition (e.g. Crohn’s disease) should also be treated.
In complicated, multiple and recurrent fistulas more complicated procedures are performed that are occasionally combined to temporary colostomy. This is why the initial surgery is of utmost importance to minimize relapse potential.
Perianal (in ano) abscesses are severe inflammations of the anorectal area extending to the perineum and requiring immediate treatment the formation of abscesses that are difficult to heal, microbemia and significant morbidity.
They manifest with acute pain in the rectal area, redness, scleria and possibly fever.
They are due to hair follicle inflammation, rectal gland, sweat glands, local contamination, hematoma-in-ano, fissure, thrombosed hemorrhoid, anal sexual intercourse, injury, Crohn’s disease and other systemic conditions. Other forms of perineal abscesses are ischiorectal, submucosal, intersphecteric, and pelvic abscesses.
The bacteria causing them are numerous, both airborne (E.coli, Enterococci, Staphylococci, etc.) and anaerobic (Bacteroides).
They are surgically treated solely. Surgery consists in laying open and draining abscesses via the shortest course. It may be performed under topical or regional anesthesia. However, general anesthesia is usually preferred because of the pain and in order to investigate the area thoroughly and to achieve better curettage of dead tissues. The procedure is not difficult but has to take place straightforward. If not, there is the risk of spontaneous rupture and occurrence of fistula, expansion to surrounding tissues that will create myonecrosis, inflammation of the genitals and occurrence of a generalized septic condition.
Antibiotics contribute to that effect and pus should be sent for performing culture and antibiogram tests to determine the antibiotic treatment that is suitable to prevent microbemia. Specimens should also be harvested and sent for biopsy if Crohn’s disease or malignancy is suspected. It should be noted that antibiotic treatment per se does not suffice and that surgery is life saving and crucial for the patient.