You are in: eMedicine Specialties > Pediatrics: Surgery > General Surgery Fistula-in-AnoArticle Last Updated: Apr 25, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Jayant Deodhar, MD, Associate Professor in Pediatrics, BJ Medical College, India; Honorary Consultant, Departments of Pediatrics and Neonatology, King Edward Memorial Hospital, India Coauthor(s): Aquil R Khan, MS (Pediatric Surgery), MBBS, Consulting Staff, Department of Pediatric Surgery, KEM Hospital, India Editors: Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Andre Hebra, MD, Clinical Associate Professor, Department of Surgery, University of South Florida School of Medicine; Director, Minimally Invasive Pediatric Surgery Program, Chief of Surgery, All Children's Hospital; H Biemann Othersen Jr, MD, Professor of Surgery and Pediatrics, Emeritus Head, Division of Pediatric Surgery, Medical University of South Carolina; Harsh Grewal, MD, FACS, FAAP, Professor of Surgery and Pediatrics, Temple University School of Medicine; Chief, Section of Pediatric Surgery, Temple University Children's Medical Center Author and Editor Disclosure Synonyms and related keywords: fistula-in-ano, fistula in ano, anal fistula, anal fistulae, perianal abscess, perineal fistula, perineal opening, rectal fistula, rectal opening, perianal infection, Kshara sutra, seton, tuberculosis, Crohn disease, immunocompromise, perianal abscess, cryptitis, congenital fistula-in-ano, imperforate anus, urinary tract infection, acquired fistula-in-ano, ulcerative colitis, submucosal fistula, intersphincteric fistula, transsphincteric fistula INTRODUCTIONSection 2 of 12
  A fistula is an abnormal communication between 2 epithelial-lined organs. The communication is usually between the anal canal and the perineal skin. In the congenital varieties, the fistulous tract may extend from the anal canal to the vestibule, vagina, or urethra. History of the ProcedureAs a clinical entity, fistula-in-ano has well been recognized from ancient times. Hippocrates (460 BC) used a seton to cure fistula-in-ano. The great Indian surgeon Sushruta (1600 BC) used a caustic ligature (Kshara sutra) to treat fistula-in-ano. In 1337, John Anderne was the first to surgically lay open a fistula-in-ano. ProblemFistula-in-ano is a fistulous connection between the anal canal and the perineum. It is usually secondary to perianal infections and, rarely, secondary to a congenital defect.1 FrequencyFistula-in-ano is not common in children compared with adults; most cases occur in adults. Fistula-in-ano is more common in boys than in girls, and 96% of cases occur in infants younger than 1 year. At King Edward Memorial (KEM) Hospital in Pune, India, this condition is present in 0.18% of admitted patients. EtiologyThe congenital type is an uncommon developmental defect. The acquired type is secondary to a perianal abscess, tuberculosis (in developing countries), Crohn disease, or immunocompromise. PathophysiologyIn the congenital form, the fistulous tract is lined with stratified squamous epithelium, columnar epithelium, or both. The acquired form manifests with repeated perianal abscesses and has an inflamed fibrous tract lined by granulation tissue and no epithelial lining upon microscopic examination. In the infected form of fistula-in-ano, the crypts of Morgagni are deeper (3-10 mm) than normal (1-2 mm). This abnormality facilitates the trapping of bacteria, which cause cryptitis that leads to perianal abscess formation and fistulae. Abnormal anal glands2 and hormonal imbalances have also been proposed as causes of fistula-in-ano. Androgen excess may stimulate the sebaceous glands, resulting in secondary infection. ClinicalCongenital fistula-in-ano Newborns with fistula-in-ano may or may not have an anus as part of the spectrum of imperforate anus. Male neonates may pass meconium per the urethra through a fistula located in the perineum, usually anterior to the normally located anus. In female neonates, meconium can be passed through the vagina, vestibule, or perineum. Both boys and girls present with recurrent urinary tract infection if fistula-in-ano is untreated. Acquired fistula-in-ano More than 96% of cases occur in infants younger than 1 year. The usual presentation involves a recurrent perianal abscess, which may or may not have been surgically treated. Two distinct views have been expressed regarding perianal abscess and fistula-in-ano. In the first view, perianal abscess is regarded as a precursor to fistula-in-ano. More than 95% of patients with perianal abscesses that lead to fistula-in-ano are boys younger than 1 year. The second view is that perianal abscess and fistula-in-ano are 2 distinct entities. Perianal abscesses are seen in 22% of girls with fistula-in-ano, 68% of whom present after age 2 years. Examination of the perineum may reveal an external opening of the fistula, with an outpouching of granulation tissue or purulent discharge. The fistula may appear as a perianal abscess. An internal opening may be felt as a nodule on the wall of the anal canal. The opening is invariably single. Probing the fistula should be done with the patient under anesthesia to avoid creating false passages. INDICATIONSSection 3 of 12
Surgery is required if pain is severe, if medical treatment fails, or if the fistula-in-ano recurs. RELEVANT ANATOMYSection 4 of 12
The anal canal is the part of the hind gut that extends from the anal ring to the anal verge. The dentate line, which is the site of the cloacal membrane, divides the anal canal into the proximal part, lined by columnar epithelium, and the distal part, lined by squamous epithelium. At the level of the dentate line, transverse folds of mucosa form a ring of valves with pockets called the crypts of Morgagni. The anal glands open in the crypts. The glands branch out and lie in the submucosal plane or, most frequently, in the intersphincteric plane. CONTRAINDICATIONSSection 5 of 12
Associated severe medical conditions may contraindicate surgical procedure or anesthesia. WORKUPSection 6 of 12
Lab Studies
Imaging Studies
TREATMENTSection 7 of 12
Medical therapyMedical therapy includes antibiotics and analgesics. In addition, treatment of the cause (eg, malignancy, Crohn disease, ulcerative colitis) is necessary. If underlying tuberculosis is detected, antitubercular treatment using rifampicin, isoniazid (Isonex), and ethambutol should be administered for 6 months. Surgical therapyAsymptomatic fistulae require no treatment. Submucosal, intersphincteric, or low transsphincteric fistulae may be adequately treated using fistulectomy or fistulotomy. Treatment varies according to the patient's sex and according to the type of fistula. Fistulectomy With the patient under anesthesia, the fistula tract is dissected from all sides by means of sharp dissection with scissors or diathermy from the external opening to the internal opening. The cavity left behind is allowed to heal by secondary intention. Fistulotomy With the patient under anesthesia, the fistula tract is probed. The probe is passed from the external opening and taken out from the internal opening. The whole fistula tract is then laid open over the probe. As with fistulectomy, the wound is allowed to heal by secondary intention. Treatment of high anal fistula A supralevator (pelvirectal) fistula may be secondary to local disease. If a traumatic fistula perforates the rectal ampulla, colostomy is usually needed. Treatment of transsphincteric fistula A transsphincteric fistula usually starts as an intersphincteric tract with a secondary tract in the ischiorectal fossa extending up to the levator axis. Treatment is directed toward the lower part of the tract, as healing of the upper tract may occur. If this does not take place, colostomy is required. Treatment of intersphincteric high anal fistula This primarily starts as an abscess of the anal gland and extends upward and downward between the internal and external sphincters. Patients may have an opening into rectum above the anorectal ring. Treatment consists of laying open the tract by dividing only a small segment of the internal sphincter. Use of seton, including medicated seton (Kshara sutra) A seton is a surgical thread often used to treat this condition. The seton can be silk, cotton, or any other suture material. It may be coated with medications. A Kshara sutra is a medicated thread often used in India to treat fistula-in-ano.3 To prepare this medicated type of seton, equal amounts of milk from the Euphorbia neri-folic plant and powder of dry rhizomes from the plant Carcuma longa are thoroughly mixed. Cotton surgical threads (No. 20) are immersed in the mixture for 1-2 hours and then dried in hot air. This procedure is repeated often, sometimes as many as 7 times. With the patient under anesthesia, the fistulous tract is probed to determine its extent and direction. A silver malleable probe is passed into fistula tract, and a suitable length of seton (Kshara sutra) is cut and threaded over the eye of the probe. The Kshara sutra is moderately tightened and is tied outside the anal verge over a piece of gauze. A new piece of Kshara sutra is replaced and tied every 6 days, using the railroad technique, until the last seton cuts through the fistula tract. The thread is shortened during each change, and the tract shortens. The wound heals by secondary intention. The fistulous tract is cut as a result of the pressure the Kshara sutra exerts on the anorectal tissue. The presence of the Kshara sutra does not allow the cavity to close and facilitates continuous drainage of pus. Cutting and healing of the tract occurs simultaneously, and no pus pocket is retained. Chemicals applied on thread are anti-inflammatory agents and have antibacterial properties. In addition, the alkaline pH of the Kshara sutra prevents rectal pathogens from invading the cavity. Postoperative detailsAbout 95% of patients are completely cured, and 5% have a recurrence. Subsequent application of a Kshara sutra is painless in 85% patients. Follow-upFollow-up care involves antibiotic treatment, surgical dressing, and use of laxatives. A high-fiber diet is recommended. COMPLICATIONSSection 8 of 12
Complications of fistula-in-ano include recurrence, delayed and/or impaired healing, anal disease, mucosal prolapse (which is not uncommon after fistula surgery), and incontinence. OUTCOME AND PROGNOSISSection 9 of 12
Outcome is good for the acquired and congenital varieties. Recurrence and scarring are common in patients with tuberculosis or Crohn disease. ACKNOWLEDGMENTSSection 10 of 12
The authors would like to thank Anand Pandit, MD, director of the department of pediatrics at King Edward Memorial Hospital, for his encouragement and help. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Article Last Updated: Apr 25, 2008 | ||||||||||||
