Anal Stenosis


Anorectal surgery

   Hemorrhoidectomy/Whitehead amputative hemorrhoidectomy

   Excision of low lying tumors

   Extensive debridement/fulguration of condyloma

   Wide excision of Paget’s disease or Bowen’s disease

Anastomotic stricture from coloanal or ileoanal anastomosis

   Pull-through procedures in children with Hirschsprung’s disease/imperforate anus

Trauma

Inflammatory Bowel disease

Radiation

Infections

   Sexually transmitted disease

   Tuberculosis

Chronic laxative abuse

Neoplasia

Congenital abnormalities



Anal stenosis has been classified by severity and location, and treatment can be tailored by this classification (Tables 13.2 and 13.3). Anal stenosis is typically diagnosed based on symptoms, with difficulty in evacuation and narrow stool most common. Table 13.4 lists common symptoms of anal stenosis. Examination typically reveals narrowing or the inability to pass a finger without discomfort. The constellation of difficulty with evacuation and inability to pass an examining finger are diagnostic [1, 18]. Exam under anesthesia may be necessary to delineate the extent of the disease if unable to examine in the office setting.


Table 13.2
Classification of anal stenosis
























Classification by severity

Classification by location

Classification by extent

Mild: Exam can be completed with finger or medium Hill Ferguson retractor

Low: At least 0.5 cm distal to dentate line

Localized: one level or quadrant of the anal canal

Moderate:

Dilation need to examine with finger or medium Hill Ferguson retractor

Mid: 0.5 cm distal to 0.5 cm proximal to dentate line

Diffuse: more than one level or quadrant

Severe:

Unable to examine with little finger or small Hill Ferguson unless forcefully dilated

High: At least 0.5 cm proximal to dentate line

Circumferential: entire circumference



Table 13.3
Treatment options for anal stenosis























 
Low stenosis

Mid stenosis

High stenosis

Mild/Moderate stenosis

Dilation

Y-V anoplasty

Dilation

Stricturotomy/stricturoplastya

Mucosal advancement flap

U-Flap

House Flap

Diamond Flap

Endoscopic Dilation

Transanal stapled reanastomosisb

Mucosal Advancement flap

U-Flap

House Flap

Severe stenosis

U-flap

House flap

Diamond flap

U-Flap

House Flap

Diamond Flap

S-Plasty

U-Flap

House Flap


aFor short strictures and high-risk patients

bFor stricture less than 1 cm from colo/ileoanal anastomosis and after stapled hemorrhoidopexy



Table 13.4
Symptoms of anal stenosis





















Constipation

Decrease in stool caliber

Difficulty initiating evacuation

Incomplete evacuation

Tenesmus

Diarrhea

Bleeding

Seepage and wetness (if associated with ectropion)



Treatment


Treatment of anal stenosis will vary depending on the location, severity, and cause of the stenosis (Tables 13.2 and 13.3). Patients with stenosis from infectious causes or inflammatory bowel disease should undergo appropriate medical treatment for the underlying condition.


Non-operative Treatment


For patients with mild/moderate low stenosis, nonoperative treatment should be instituted, with stool softeners/bulking agents and dilation. Dilation is appropriate for stenoses from coloanal or ileoanal pull-through procedures, from crohn’s disease and radiation [19]. In children, dilation is routinely performed after pull-through procedures for Hirschsprung’s disease and anorectal malformations in order to prevent the development of anastomotic stenosis [20, 21].

For strictures from coloanal or ileoanal anastomoses, dilation may be successful, and should be initiated within the first several weeks after surgery, and digital dilation by the examiner may be all that is required [22].

In adults, there are few published standardized methods for dilation as there are in children [3, 20]. Several authors advocate performing the first dilation in the operating room using Hegar dilators followed by daily dilation at home [3, 19]. Success will therefore require a compliant and motivated patient. For those patients with mild stenosis from Crohn’s disease, about half will respond to dilation [19]. Shorter strictures will respond better to dilation than longer strictures [14].

For anastomotic strictures or those from stapled hemorrhoidopexy procedures that are located slightly higher, endoscopic balloon dilation can also be performed. Dilation for stricture is relatively safe, however, complications such as perforation can occur [23, 24]. Pain from repeated dilation may lead to decrease in success of treatment, especially in children [21]. Sphincter damage leading to fecal incontinence is also a concern with repeated dilations [1, 24].


Operative Treatment


Operative treatment is indicated for patients with moderate to severe stenosis, with stenosis associated with ectropion, and for those with mild stenosis who fail non-operative treatment.

A variety of operative procedures has been described for the treatment of anal stenosis. These should be tailored to the individual patient and the surgeon’s familiarity with the procedures. Preoperative workup prior to surgical repair is typically minimal as many patients will not tolerate an exam in the clinic. Adjuncts such as endoanal ultrasound or manometry, although helpful in determining the status of the sphincters, will not be tolerated by most patients. Examination under anesthesia in the operating room is the most important for preoperative planning [3, 19].


Flaps


There are a several flaps that have been described in the treatment of anal stenosis (Table 13.3) which are described below. Flaps can be sliding (mucosal advancement, V-Y), island (Diamond, U, House), or rotational (S-plasty).

Mucosal Advancement flaps are best for mid- or high stenosis [19]. The procedure is performed laterally, and can be performed bilaterally if necessary. A radial incision is made through the scar and extending to the anal verge. The scar is excised, sphincterotomy performed, and a mucosal flap raised for 2–5 cm in length. The flap is then sutured to the intersphincteric groove, with a resultant small external wound [1]. Advantages of the mucosal advancement flap are minimal morbidity [25], small perianal wounds, and the ability to perform bilateral flaps if needed. Disadvantages include mucosal ectropion if the suture line is too distal and a higher rate of restenosis in treating distal severe disease [25].

Y-V anoplasty is another sliding flap which involves the use of a Y-shaped incision which is then sutured as a V [26]. See Fig. 13.1. The base of the Y incision (medial most aspect) should be shorter than the top of the Y (lateral aspect) to ensure that the flap has enough mobility to cover the entire defect. Care must be taken to raise a full thickness flap, as the blood supply is maintained from the most lateral aspect of the flap. Ischemia of the flap can occur if there is tension or if the flap is not the full thickness, with resultant dehiscence or restenosis [10, 27]. Benefits of this flap are its ease of performance, and no open wounds.

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Fig. 13.1
Y-V Anoplasty—from Fig. 41.1, Blumetti and Abcarian, Anal canal resurfacing in Anal stenosis, Chap. 41, pp 437–445, Zbar AP, Madoff RD, Wexner SD, eds. Reconstructive Surgery of the Rectum, Anus and Perineum Springer London 2013. a Anal Canal. b Line of Incision for Y-V anoplasty. The distance between the arms of the Y should be equal or greater to the length of the Y to allow a tension free closure. c Completed Y-V anoplasty

Island flaps are fully mobilized from the surrounding skin, which can allow further mobilization into the anal canal, making them useful in the treatment of higher stenoses. The blood supply to these flaps is through the subcutaneous tissue and allows for full mobilization and a tension-free anastomosis [2830]. The diamond flap as described by Caplin and Kodner [4] begins with release of the scar via a lateral incision, and internal sphincterotomy can be performed if needed. This results in a diamond-shaped defect (Fig. 13.2). The flap is then drawn laterally to the incision, with the half of the flap closest to the anus being the size of the previously made incision. The full thickness flap is then created, with care taken to avoid undermining the flap, which can result in ischemia. The flap is then sutured into place and all the defects closed. This flap can also be performed bilaterally if necessary, and can be performed after failed Y-V.
Oct 18, 2017 | Posted by in GASTROENTEROLOGY | Comments Off on Anal Stenosis
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