Fistulas PDF

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Summary

notes on management of different types of fistulas in the GI tract...

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Fistulas Fistulas A fistula is defined as an abnormal connection between two epithelial surfaces. There are many types ranging from Branchial fistulae in the neck to enterocutaneous fistulae abdominally. In general surgical practice the abdominal cavity generates the majority and most of these arise from diverticular disease and Crohn's. As a general rule all fistulae will resolve spontaneously as long as there is no distal obstruction. This is particularly true of intestinal fistulae. The four types of fistulae are: Enterocutaneous Enteroenteric or Enterocolic This is a fistula that involves the large or small intestine. They may originate in a similar manner to enterocutaneous fistulae. A particular problem with this fistula type is that bacterial overgrowth may precipitate malabsorption syndromes. This may be particularly serious in inflammatory bowel disease. Enterovaginal Aetiology as above. Enterovesical This type of fistula goes to the bladder. These fistulas may result in frequent urinary tract infections, or the passage of gas from the urethra during urination. General Management Some rules relating to fistula management:

They will heal provided there is no underlying inflammatory bowel disease and no distal obstruction, so conservative measures may be the best option Where there is skin involvement, protect the overlying skin, often using a well fitted stoma bag- skin damage is difficult to treat A high output fistula may be rendered more easily managed by the use of octreotide, this will tend to reduce the volume of pancreatic secretions. Nutritional complications are common especially with high fistula (e.g. high jejunal or duodenal) these may necessitate the use of TPN to provide nutritional support together with the concomitant use of octreotide to reduce volume and protect skin. When managing perianal fistulae surgeons should avoid probing the fistula where acute inflammation is present, this almost always worsens outcomes. When perianal fistulae occur secondary to Crohn's disease the best management option is often to drain acute sepsis and maintain that drainage through the judicious use of setons (loose) whilst medical management is implemented. Always attempt to delineate the fistula anatomy, for abscesses and fistulae that have an intra abdominal source the use of barium and CT studies should show a track. For perianal fistulae surgeons should recall Goodsall's rule in relation to internal and external openings.

Enterocutanous Fistula These link the intestine to the skin. They may be high 500ml) or low output 250ml) depending upon source. Duodenal /jejunal fistulae will tend to produce high volume, electrolyte rich secretions which can lead to severe excoriation of the skin. Colo-cutaneous fistulae will tend to leak faeculent material. Both fistulae may result from the spontaneous rupture of an abscess cavity onto the skin (such as following perianal abscess drainage) or may occur as a result of iatrogenic input. In some cases it may even be surgically desirable e.g. mucous fistula following sub total colectomy for colitis. Risk factors

Pre-operative risk factors previous abdominal surgery surgery for IBD malnourished patient septic pateint steroids surgical risk factors extensive adhesiolysis/enterotomy injudicious anastomosis repeat laparotomy Classification anatomical site type: primary or secondary (injury to normal gut, surgery, radiation, trauma) physiological: high output 500ml/day) Mangement low output - if no distal obstruction, then expected to heal high output- unlikely to heal by themselves SNAP Principle stabilisation- IV fluids and fluid monitoring, electrolyte replacemnt, control of sepsis, skin protection with zinc oxide paste, somatostain anagloude (octerotide), PPI Nutrition- TPN or Enteral Anatomy- fistulogrpahy, CT, MRI ,small bowel follow through Plan - 8090% will close spontaneously in 6 weeks, if not optimise pt and plan to operate in 1012 weeks. Mainstay is the restoration of bowel continuity and reconstuction of abdominal wall Suspect if there is excess fluid in the drain.

Colovesical Fistulae This type of fistula goes to the bladder. These fistulas may result in frequent urinary tract infections, or the passage of gas from the urethra during urination. Causes maligancy diverticulosis IBD Presentation recurrent UTI faecal material per urethra pneumoturia Assessment urinanlysis CT scan- most sensitive Cystoscopy flexible sigmoidoscopy Management surgical excision primary repair and/or defunctioning stoma (haartman's) bladder repair and catheter placement

Anal fistula About Fistula in ano is the most common form of ano rectal sepsis. Fistulae will have both an internal opening and external opening, these will be connected by

tract(s). Complexity arises because of the potential for multiple entry and exit sites, together with multiple tracts. Fistulas usually occur following previous ano-rectal sepsis. The discharge may be foul smelling and troublesome. Patients should be listed for examination under anaesthesia. Fistulas which are low and have little or no sphincter involvement are usually laid open. incidence 1020 per 100,000 per year Cause majority- not immediately apparent minority- specific cases a third of patients with ahistory of perianal abscess will present with a fistula at a later date Types simple complex multiple openings involving more than 3050% of the external sphincter blind high extensions horshoe extensions hisotry of IBD anterioly placed in women pre-existing faecal incontinence

Assessment Examination of the perineum for signs of trauma, external openings or the stigmata of IBD is important. Digital rectal examination may reveal the cord linking the internal and external openings. At the same time the integrity of the sphincter mechanism can be assessed. Low, uncomplicated fistulas may not

require any further assessment, other groups will usually require more detailed investigation. the use of endo-anal USS with instillation of hydrogen peroxide into the fistula tract may be helpful. Ano-rectal MRI scanning is also a useful tool, it is sensitive and specific for the identification of fistula anatomy, branching tracts and identifying occult sphincter involvement. gold standard for anal abscess Identification of the internal opening Fistulas with an external opening less than 3cm from the anal verge will typically obey Goodsalls rule Anterior fistulae will tend to have an internal opening opposite the external opening. Posterior fistulae will tend to have a curved track that passes towards the midline.

Therapies Main goals of management

cure fistula prevent recurrence retain continence Seton suture A seton is a piece of material that is passed through the fistula between the internal and external openings that allows the drainage of sepsis. This is important as undrained septic foci may drain along the path of least resistance, which may result in the development of accessory tracts and openings. Their main use is in treating complex fistula. Two types of seton are recognised, simple and cutting. Simple setons lie within the fistula tract and encourage both drainage and fibrosis. A cutting seton is inserted and the skin incised. The suture is tightened and re-tightened at regular intervals. This may convert a high fistula to a low fistula. Since the tissue will scar surrounding the fistula it is hoped that this technique will minimise incontinence. Unfortunately, a large retrospective review of the literature related to the use of cutting setons has found that they are associated with a 12% long term incontinence rate Fistulotomy Low fistulas, that are simple should be treated by fistulotomy once the acute sepsis has been controlled. Fistulotomy (where safe) provides the highest healing rates 90%. Because fistulotomy is regarded as having a high cure rate, there are some who prefer to use this technique with more extensive sphincter involvement. In these patients the fistulotomy is performed as for a low fistula. However, the muscle that is encountered is then divided and reconstructed with an overlapping sphincter repair. A price is paid in terms of incontinence with this technique and up to 12.5% of patients who were continent pre-operatively will have issues relating to continence post procedure. The same group also randomised between fistulotomy and sphincter reconstruction and ano-rectal

advancement flaps for the treatment of complex cryptoglandular fistulas and reported similar outcomes in terms of recurrence 90% and disturbances to continence 20%.Other authors have found adverse outcomes following fistulotomy in patients who have undergone previous surgery, are of female gender or who have high internal openings , in these patients careful assessment of pre-operative sphincter function should be considered mandatory prior to fistulotomy. Anal fistula plugs and fibrin glue biologic plug made from procine small intestinal mucosal resistant to infection no foreign body reaction allows host cell population to close the tract Meticulous preparation of the tract and prior use of a draining seton is likely to improve chances of success. The use of anal fistula plugs in high transphincteric fistula of cryptoglandular origin is to be discouraged because of the high incidence of non response in patients treated with such devices. In most patients septic complications are the reasons for failure. Fibrin glue is a popular option for the treatment of fistula. There is variability of reported healing rates In some cases initial success rates of up to 50% healing at six months are reported (in patients with complex cryptogenic fistula). Of these successes 25% suffer a long term recurrence of fistula. There are, however, no obvious cases of damage to the sphincter complex and the use of the devices does not appear to adversely impact on subsequent surgical options. Ano-rectal advancement flaps This procedure is primarily directed at high fistulae, sphincter saving The procedure is performed either with the patient in the prone jack knife position or in lithotomy (depending upon the site of the fistula). The dissection is commenced in the sub mucosal plane (which may be infiltrated with dilute adrenaline solution to ease dissection). The dissection is continued into

healthy proximal tissue. This is brought down and sutured over the defect.Follow up of patients with cryptoglandular fistulas treated with advancement flaps shows a success in up to 80% patient. With most recurrences occurring in the first 6 months following surgery. Continence was affected in some patients, with up to 10% describing major continence issues post operatively. Ligation of the intersphincteric tract procedure In this procedure an incision is made in the intersphincteric groove and the fistula tract dissected out in this plane and divided. A greater than 90% cure rate within 4 weeks was initially reported. Others have subsequently performed similar studies on larger numbers of patients with similar success rates. Fistulotomy at the time of abscess drainage? immediate fistulotomy at the time of drainage should be considered in patients with low, sub-mucosal and inter-sphincteric fistulae more complex sepsis and fistula shoudl be simply drained anatomical assessment can be difficult in the acute setting

Fistula in Crohn's Disease 1/3 of patients with corhns will have an anal fistula emergency treatment- incision and drainage stabilisation with isnertion of a loose silastic seton consider metronidazole ultimately need medical therapy...