Overlapping Sphincter Repair

For most women with fecal incontinence secondary to obstetric trauma, sphincter damage is often occult, persistent, or associated with pudendal nerve damage leading to fecal incontinence many years after delivery. For women with fecal incontinence secondary to a functional yet anatomically disrupted anterior EAS, overlapping sphinc-teroplasty is the operation of choice. This technique is the result of an evolution of a variety of modifications of the initial descriptions of sphincter repair. Initial reports involved identification and mobilization of the EAS, excision of all scar tissue, and direct apposition of muscle ends. Further modifications associated with significant improvement in functional outcome included overlapping of the ends of the muscle and avoidance in excising any associated scar tissue. Additionally, it was found that sphinctero-plasty could be safely performed without fecal diversion if an appropriate bowel preparation was used. Other modifications including levatorplasty and repair of the IAS have further been incorporated.4

Candidacy for this procedure is based on clinical history, physical examination, and physiologic evaluation. A bowel habit history with regard to the stool consistency, the number of bowel movements in a 24-hour period, symptoms of urgency, the ability to defer defecation, staining of the undergarments, and any loss of control of bowel movements is obtained. In women, an obstetric history should be obtained with specific questions regarding episiotomies, tears, and assisted delivery with suction or forceps. A surgical history should be inquired concentrating on surgical procedures for fissures, hemorrhoids, fistulas, and tumors. Any history of pelvic irradiation or success with previous therapies is important.

The physical examination begins with inspection of the anorectal region. Important clinical findings include appearance of the anus at rest (open versus closed), visible contraction with squeeze, and the presence of any scars. Digital rectal examination provides additional information with particular regard to resting (IAS) and squeeze pressures (EAS). The thickness of the rectovaginal septum and any associated sphincter defects should be noted. Sensation is evaluated by touching the perianal skin with a sharp object. Anoscopic and endoscopic evaluation often complete the examination.

The incontinence score guides both the intensity of the investigation and any subsequent therapeutic decisions because its takes into account the severity, type, and degree of incontinence with consideration of its effect on lifestyle. Conservative measures, including medical intervention and biofeedback, are reserved for patients with low incontinence scores or who are poor surgical candidates. Only moderately or severely incontinent patients whose lifestyles are significantly affected should be offered surgical intervention. Physiologic evaluation is important in not only determining candidacy for these procedures, but also in assigning prognosis. The typical physiologic evaluation involves endoanal ultrasound, anal manometry, elec-tromyography, and pudendal nerve terminal motor latency (PNTML) testing. Discovery of isolated anterior sphincter defects warrants surgical correction in appropriate patients before implementation of other techniques.

Initial physiologic evaluation of patients suspected of having an isolated sphincter defect involves endoanal ultrasound (EAUS). At our institution, EAUS is performed in the office and gives structural information about the integrity of the IAS, EAS, and puborectalis as well as the presence and location of any defects or scars (see Chapter 3-5). This study will ultimately help determine the type of surgery from which the patient may most benefit. If the EAUS reveals a single defect in the IAS and EAS or the EAS alone, the patient may be a candidate for an overlapping sphincteroplasty. If the ultrasound reveals multifocal defects or an intact muscle, the patient may benefit from either biofeedback or alternative surgical intervention such as sacral nerve stimulation or sphincter reconstruction or replacement. Anal magnetic resonance imaging provides similar information when performed with an anal coil, but this procedure is more expensive and less comfortable for the patient.

Discovery of an isolated IAS defect poses a challenging problem because it is not the sole cause of incontinence in symptomatic patients. Repair of isolated defects in the IAS is controversial because studies have not clearly shown benefit in incontinent patients without EAS damage. However, some surgeons may repair the defect in conjunction with overlapping repair of the EAS, although this method has not yielded better results than overlapping the EAS alone. An isolated defect in the IAS should be followed by evaluation for other causes of incontinence and for rec-toanal intussusception (cinedefecography) with concomitant pudendal neuropathy (PNTML). An IAS defect alone without intussusception or pudendal neuropathy is usually treated with biofeedback therapy. However, newer therapies such as submucosal injection of carbon-coated beads and the administration of endoanal radiofrequency energy may be useful in these cases.

Further physiologic testing includes anal manometry and anal electromyography. Anal manometry is the least useful in determining the etiology of the incontinence; however, it provides important information about pressures, compliance, sensation, and reflexes of the anorectal region (see Chapter 3-4). Anal manometry confirms any sphincter damage by decreased resting (function of the IAS) and/or squeeze (function of the EAS) pressures. Manometry will also identify other abnormalities that may not be corrected by sphincter repair such as decreased rectal compliance (inflammatory bowel disease, radiation proctitis), intrinsic nerve impairment/loss in the form of absent rectoanal inhibitory reflex (adult Hirschsprung's, Chagas' disease), or decreased anal or rectal sensation (aging). These abnormalities may be improved with nonoperative therapy in the form of biofeedback with sensory retraining or other forms of surgery (proctectomy, stoma) in addition to or instead of sphincter repair.

Electromyography (EMG) records action potentials derived from motor units within a contracting muscle. It allows functional correlation of the EAUS in a quadrant-by-quadrant manner. Before EAUS, EMG was used for "mapping" sphincter defects using needle electrodes. An anterior defect of the anal sphincter on EAUS should have an appropriate decrease in the level of muscle function on EMG in the anterior quadrant. Electromyography will also provide information about the functional quality of the intact sphincter in the remaining three muscle quadrants (posterior, left, and right). Increased fiber density, or polyphasia, and/or the absence of action potentials is suggestive of either neural damage or significant muscular degeneration. This inadequate neuromuscular function may argue against a successful outcome after overlapping sphincteroplasty. Overlapping sphincteroplasty may still be recommended as the initial surgical therapy in this situation after thorough counseling. However, these patients may require additional therapy in the form of biofeedback, sacral nerve stimulation, or neosphincter procedures if an inadequate result is obtained.

To complete the physiologic evaluation of the patient with incontinence, measurement of the PNTML is routinely performed. Damage to the EAS may be accompanied by injury to the pudendal nerve that manifests as prolonged pudendal nerve latency (see Chapter 3-6). A PNTML of more than 2.2 milliseconds is considered abnormal at our institution. Pudendal neuropathy corresponds on EMG to a decreased or absent action potentials or polyphasia. Pudendal nerve damage may contribute to incontinence after obstetric trauma and is found to be a poor prognostic factor after overlapping sphincteroplasty. However, prolonged PNTML may not preclude sphincteroplasty after extensive counseling.5 A waiting period of 6 to 12 months may allow time to recover after a birthing injury; however, if the injury is remote, recovery is unlikely.

At our institution, the technique of overlapping sphinc-teroplasty for the treatment of isolated anterior EAS defects is generally performed without the use of a stoma. Preoperative management includes full mechanical bowel preparation (45mL of Fleets Phospho-Soda per os at 4:00 pm and at 9:00 pm, each followed by three 8-oz glasses of water) and oral antibiotics (1g of neomycin and 500mg of metronidazole at 1:00, 2:00, and 11:00 pm) the day before surgery. In addition, 2 g of cefotaxime and 1g of metron-idazole are administered intravenously as well as 5000 units of heparin subcutaneously at the start of the operation. The patient is positioned in the prone jackknife position on a Kraske roll with PAS stockings. The procedure is performed under general anesthesia although regional (caudal or spinal) anesthesia can be substituted. After sterile preparation of the perianal area, vagina, and perineum, a circumanal and bilateral nerve block is achieved with a mixture of 0.25% Marcaine (bupivacaine) and 0.5% Xylocaine with 1:400,000 units of epinephrine. A 120-degree curvilinear incision is made anterior to the anus, approximately 0.5 cm distal and parallel to the anal verge. The anterior portion of the sphincter muscle is identified and dissected with the index finger of the nondominant hand inserted into the vagina. This maneuver aids in the prevention of inadvertent vaginal wall injury. In addition, care must be taken not to extend the dissection through the mucosa into the anal canal or rectum, particularly in areas where the sphincter muscle is disrupted or absent or the rectovaginal septum is extremely thin. Such an injury predisposes to the development of an anovaginal or recto-vaginal fistula. Dissection of the EAS is initiated laterally where the muscle anatomy is usually intact and can aid the surgeon in identifying the proper plane of dissection. Additionally, care must be taken not to injure the pudendal nerve bundles that enter the EAS bilaterally in the pos-terolateral positions. The intersphincteric space is dissected from lateral to medial on each side and the internal and external sphincters are separated (Figure 6-8.2). If scar tissue is connecting the two ends of the disrupted external sphincter, the scar is divided in the midline, but not excised. It is important to preserve all scar tissue in order to better anchor the sutures. If the ends are separated,

Figure 6-8.2. Dissection of the external anal sphincter and division of the anterior scar.

(Reprinted from Wexner SD, Beck DE. Fundamentals of Anorectal Surgery. 2nd ed. p 133-136, Copyright 2001 WB Saunders, with permission from Elsevier.)

Figure 6-8.2. Dissection of the external anal sphincter and division of the anterior scar.

(Reprinted from Wexner SD, Beck DE. Fundamentals of Anorectal Surgery. 2nd ed. p 133-136, Copyright 2001 WB Saunders, with permission from Elsevier.)

the scar is identified and preserved and the muscle is mobilized.

The repair starts with the imbrication of the levator muscles, found just beneath the two ends of divided scar tissue, using interrupted 2-0 polypropylene sutures. The IAS is plicated with interrupted 2-0 polydioxane acid sutures (Figure 6-8.3). These sutures are placed far enough laterally for a snug repair that is then verified by inserting an index finger into the anal canal. At this point in the procedure, the ends of the external sphincter muscle should overlap without significant tension and are secured with interrupted 2-0 polydioxane mattress sutures, using the scar tissues to provide a significant portion of the suture fixation (Figure 6-8.4). All retractors and buttocks tapes are removed before tying of the sutures of the overlapped ends to avoid a lax repair. The sutures are tied snugly but not so tight as to induce muscular ischemia. The wound is closed from lateral to medial on each side using 3-0 polyglactin sutures through the skin, leaving the central-most portion of the wound open for drainage.

Postoperatively, the patient receives 2 g of cefotaxime every 12 hours and 500mg of metronidazole every 6 hours for 2 days, followed by oral ciprofloxacin and metronida-zole for 7 days. Ambulation is encouraged and long periods of sitting are discouraged. The wound is not packed, although patients may need a pad to protect clothing. Bowel confinement has not been used since completion of a prospective, randomized trial at our institution in which no advantage was found over starting a regular diet.6

Short-term outcome of overlapping sphincteroplasty yields extremely good short-term functional results with an overall reported early success rate of 71% to 86% during a mean follow-up of 10 to 29 months.2 At our institution, 55 women who underwent overlapping sphincteroplasty were analyzed over a period of 29 months.5 More than 95% had a history of previous vaginal delivery and 55% had had a previous sphincter repair. The outcome was excellent in

Figure 6-8.3. Apposition of the levator and anterior plication of the internal anal sphincter. (Reprinted from Wexner SD, Beck DE. Fundamentals of Anorectal Surgery. 2nd ed. p 133-136, Copyright 2001 WB Saunders, with permission from Elsevier.)
Anorectal Surgery Pictures
Figure 6-8.4. Overlapping repair. (Reprinted from Wexner SD, Beck DE. Fundamentals of Anorectal Surgery. 2nd ed. p 133-136, Copyright 2001 WB Saunders, with permission from Elsevier.)

71% and fair in the remaining. Several important conclusions were gained from this study. A significant increase in mean squeeze pressure and high-pressure zone length correlated with better functional outcome. In other words, restoring the integrity of the sphincter muscle resulted in improved sphincter function and associated decrease in incontinence. Age was not predictive of success because this procedure was as effective in women older than age 60 as those younger than 60. Previous sphincter repairs did not predict failure with future overlapping repairs because repeat repairs were shown to demonstrate significant improvements in continence in those with residual anterior sphincter damage after a previous sphincter surgery. The major factor found to be associated with poor outcome was prolonged PNTML, a finding that has been separately confirmed in several other studies. A review of factors predictive of good outcome in overlapping sphincteroplasty revealed that the optimal conditions for this type of repair are no previous repair, preservation of scar during dissection, bilaterally intact pudendal nerves, normal rectal sensation, and an asthenic young patient with an isolated anterior EAS defect.2 However, long-term results are less gratifying, which is one of the reasons why other procedures may have a role.

As many as 60% of patients present with recurrent symptoms of fecal incontinence.7 Early or late failure of overlapping sphincteroplasty warrants repeat physiologic evaluation to determine the integrity of the repair. Identification of a persistent anterior sphincter defect should lead to contemplation of a repeat repair. In a study performed at our institution on 36 women who had a history of overlapping sphincteroplasty, patients had the same significant improvement as women with no history of repair.7 In addition, the outcome seemed similar regardless of the number of previous repairs, although no definitive conclusion could be drawn with regard to this matter because only five patients had more than one previous repair. However, repeat overlapping sphincteroplasty should be considered the treatment of choice in patients with fecal incontinence that have had one or more previous sphincter repairs in whom residual anterior sphincter damage is found. However, a functional failure despite anatomic success may be better treated with biofeedback therapy, postanal or total pelvic floor repair, stimulated graciloplasty, artificial bowel sphincter, sacral nerve stimulation, or may necessitate a permanent stoma.

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