© Borgis - New Medicine 4/2005, s. 54-56
Małgorzata Kołodziejczak1, Iwona Sudoł-Szopińska2
Causes of recurrences of anal fistulae
1Proctology, Subdepartment of Surgery, Śródmiejski Hospital, Warsaw, Poland
Head of Department: Małgorzata Kołodziejczak, MD, PhD
2Central Institute of Occupational Health – National Research Institute
Director: Professor Danuta Koradecka, MD, PhD
Department of Diagnostics Imaging, Second Faculty, Warsaw Medical Academy, Warsaw, Poland
Head of Department: Professor Wiesław Jakubowski, MD, PhD
The paper discusses the problem of anal fistula recurrence after surgery. The recurrence rate after surgical treatment of anal fistulae ranges from 0 to 26.5%, according to literature data. Most recurrences develop within a year following surgery. In most cases of recurrence, the fistulae are of type 3 and 4 according to Park´s classification (i.e. high suprasphincteric and extrasphincteric fistulae), fistulae in Crohn´s disease, and also fistulae in patients with decreased immunity and diabetes mellitus. The prophylaxis of fistula recurrence includes three stages: 1) preoperative diagnostics, 2) appropriately conducted surgery, and 3) correct postoperative management of the patient. In the preoperative diagnostics of fistula, transrectal ultrasonography, which is presently regarded as "gold standard”, should be used for assessment of both anatomical location of the fistula and sphincter muscles, and also, in individual cases, classic fistulography and the most recent imaging techniques, i.e. magnetic resonance imaging (MRI) and tri-dimentional (3D) endosonography, should be applied. The latter are used in the diagnosis of ramified fistulae of complex shape, e.g. in Crohn´s disease. Leaving of the main canal, failure to find the internal opening, which in most cases is the cause of fistula, or failure to excise all ramifications, are basic errors in surgical technique leading to disease recurrence. Other causes of fistula recurrence include too tight suturing of the surgical wound, insufficient drainage and consequent development of a new inflammatory canal as well as incorrect diagnosis of the cause of fistula, e.g. failure to remove a foreign body or to diagnose Crohn´s disease. Incorrect postoperative management, a factor that is frequently omitted in the literature, is also discussed in detail in the paper.
For many years anal fistula has been a surgical problem in view of the high number of postoperative complications such as incontinence of gases and faeces and recurrent course of the disease. The complications after anal fistula surgery can be divided into early – analogous to those after other proctologic operations, and late – characteristic only of fistula. Early complications that develop most frequently include postoperative bleeding, infectious complications and urine retention. Late complications after anal fistula surgery may include recurrence of fistula (in the form of anal abscess or anal fistula) and various degrees of symptoms and signs of anal sphincter insufficiency from slight gas incontinence to complete solid stool incontinence. The complication in the form of postoperative incontinence is a significant problem but it is not the subject of this paper. Late complication in the form of recurrence of fistula is frequent and is estimated by various authors as developing in 0 to 26.5% of cases (1, 2, 3, 4). In the Proctology Department, Srodmiejski Hospital, the percentage of fistula recurrences is about 10% and the risk factors of recurrence in our material include female sex and operations for recurrent fistulae (5). As is known, the key to anal fistula surgery is to find a golden middle between surgical procedure radicalism and preservation of anal sphincters. The authors who reported high numbers of complications in the form of faecal incontinence had a low recurrence rate and, conversely, surgeons preferring more cautious procedures had more recurrences.
It seems that such great differences result not only from application of different operation techniques. It happens, however, that different authors using the same operation technique obtain totally different results. The causes of that situation may include the fact that the clinical material is not uniform, e.g. the results of surgical treatment of low fistulae cannot be compared with those of high fistulae, and the results differ also in the case of fistulae in Crohn´s disease where recurrence rate is high, or in the case of high rectal fistulae, which usually cannot be cured without creating an artificial anus. Healing is impaired also in patients with diabetes and decreased immunity; such patients are also more prone to recurrences.
Most recurrences develop within a year following surgery (1). Taking into account the type of fistula determined according to Park´s classification of 1976 (6), most recurrences are seen in type 3 and 4 fistulae, i.e. high suprasphincteral and extrasphincteral fistulae (4). When analysing the causes of recurrences of fistulae most authors stress the errors in surgical technique (7). A high recurrence rate in the case of high fistulae can result from the surgeon´s fear of cutting the whole muscle mass and from selection of a more cautious operation method. This is a very important although not the only cause of fistula recurrence.
The prophylaxis of fistula recurrence comprises three stages:
1. Preoperative diagnostics of anatomical location of fistula.
2. Well performed operation.
3. Correct postoperative management.
Re 1. Preoperative diagnostics of anatomical shape of fistula includes in the first place physical examination and imaging examinations, particularly endosonography. The aim of proctologic examination is to assess passive and active tonus of anal sphincters, and to perform anoscopy and rectoscopy in order to localize the internal opening. During rectoscopy rectal mucosa is also examined to preclude non-specific colitis, which also can be a cause of fistula and, if untreated, can lead to disease recurrence.
Transrectal ultrasonography, regarded presently as the "gold standard”, is also used for preoperative assessment both of the anatomical course of fistula and of sphincter muscles (8, 9, 10, 11, 12, 13, 14). The accuracy of endosonography in the diagnosis of anal fistulae is, according to various authors, from 25% to 100% and, unfortunately, is lowest in the case of anal fistulae of recurrent character (14). In primary fistulae, endosonography allows the type of fistula and the site of its internal opening to be determined with high accuracy. The technique is of great value for preoperative assessment of anal sphincters. In the case of recurrent fistulae, the differential diagnosis between scar after fistula operation and active fistula, particularly its ramifications, causes some difficulties. The administration of contrast (hydrogen peroxide solution) through the external opening, and use of the most recent imaging techniques, such as MRI (15, 16) and 3D endosonography (17, 18, 19, 20), are helpful in such situations. These methods are used especially in the diagnosis of ramified (i.e. complex), high, recurrent fistulae, e.g. in Crohn´s disease. Traditional fistulography should also be kept in mind, especially in cases of iatrogenic fistulae or fistulae developing "around a foreign body”.
Re 2. Appropriate surgical technique to a large extent allows fistula recurrence to be avoided and it includes:
1. determination of fistula type, that is location of the fistula in relation to anal sphincters, particularly the external sphincter and puborectal muscles, and choice of surgical procedure type suitable for a given type of fistula,
2. finding and excision of the internal opening, i.e. the possible cause of the fistula,
3. excision of the whole fistula together with its ramifications.
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