- Preoperative clinical assessment may correlate well with the intraoperative assessment of anal sphincter injury.
- An overlapping sphincter repair without diversion is safe and effective in discrete sphincter injury.
- Extensive perineal injuries involving the rectum require a diverting stoma.
The anal sphincter is anatomically well protected by the fat tissue in the ischiorectal fossa and by the gluteal muscles and pelvic structures1. The injuries are not frequent and are mostly caused iatrogenically (surgery, childbirth), or by sexual injuries, or war injuries2–5. The aim of surgical repair is to remove this segment and recreate a long anal canal surrounded by active sphincter muscle6. Traumatic perineal injuries often occur with severe associated life-threatening injuries. The general principles of injury prioritization, perineal debridement, and diversion of the fecal stream in cases of associated rectal laceration are important2,3. The work has been reported in line with the SCARE 2020 criteria7.
A 25-year-old heterosexual African man was admitted as an emergency following a gunshot to the abdomen and another to the pelvis. He had no past medical or drug history. Following resuscitation, a laparotomy demonstrated multiple perforations of the small bowel requiring resection. The entry site of the second bullet was in the left iliac fossa that caused no pelvic injury. The exit point was through the perineum with specific injury to the posterior anal sphincter complex. There was no loss of rectal nor anal mucosal sensation, but anal tone on squeeze and active anal control were lost. He recovered from his abdominal surgery but continued to have severe urge fecal incontinence. The Cleveland Clinic Incontinence Score (CCIS) was 18/20, that is, solids (always) 4, liquids (always) 4, flatus (sometimes) 2, use of pad (always) 4, lifestyle alteration (always) 4. Rectal examination revealed mild fecal soiling and bilateral scarring from the mid anal canal at 3 and 9 o’clock extending posteriorly. This was associated with a palpable defect entailing fibrous tissue adjoining the underlying separated ends of the posterior anal sphincter complex (Fig. 1). Clinically, a diagnosis of 50% posterior anal sphincter complex damage (grade 3b) was made. He consented for repair. In the lithotomy position, the first step entailed the excision of all the secondary epithelium and underlying scar tissue surrounding the posterior margins of the anus. This created a large wound which was essential in allowing exposure of the disrupted muscle ends for opposition without tension (Fig. 2). The next step involved mobilizing the normal mucosa of the anal canal and lower rectum by dissecting it about 1 cm free from the muscle wall. This would later allow mucosal reconstruction without tension. The third and difficult step was sorting the disrupted muscle ends without cleaning off all the fibrous tissue which will aid holding the sutures. No attempt was made to identify separately the internal and external sphincters. It was necessary to dissect on the lateral surface of the sphincter for a short distance to free fibrous tissue tethered to the muscles and allow repair without tension, but not extensively which may damage the laterally placed neurovascular bundle. Posteriorly, the insertion of all the muscles attached to the coccyx were divided to allow the posterior limb of the sphincter to be lifted forwards without tension, and leaving a cavity between the coccyx and the rectum which would allow drainage. Horizontal mattress sutures with absorbable 2.0 Vicryl were used in the overlapping repair of the remnant external anal sphincter but tied lightly to avoid muscle necrosis (Fig. 3). The anal tone on palpation following the repair was satisfactory. The perineal skin was closed in an inverted “Y” (Fig. 4) and a compression dressing applied. He was administered three perioperative doses of broad-spectrum antibiotics and allowed an elemental diet for 2 weeks. His bowels moved the following day with no urge incontinence. He had no fecal incontinence at 1 year (CCIS 1/20) follow-up.
The case demonstrated sphincter damage from a gunshot that was not total but sufficient to cause appreciable loss of anorectal control. Following a section of the posterior sphincter muscles by the bullet, the sphincters had retracted to about half their circumference, that is, third-degree (3b) perineal injury. The wound had healed with much secondary epithelium and underlying scar tissue (Fig. 2, Table 1). The preoperative clinical assessment correlated well with the intraoperative assessment of the sphincter injury. Haque et al5 presented a similar experience. Specific features in the history may point to the underlying etiology of fecal incontinence. Often the history will give some indication as to whether the problem lies primarily within the rectum or the sphincter apparatus. Seepage of feces is associated with abnormalities of anal canal sensation, whereas patients with the urgency of defecation have a deficiency of external anal function8. The novelty of this case were (1) the uncommon presentation of a discrete posterior anal injury involving >50% of the external anal sphincter; (2) the satisfactory restoration of anal control following an overlapping sphincteroplasty without the need for a diverting stoma in this complex injury. Unlike external anal sphincter injury from obstetric trauma which is always anterior and in the midline, external anal sphincter muscle injury in other sites are not so easily treated as the retracted ends are difficult to define with confidence. In addition, because of their disrupted nature any suture placed in them will tend to cut out. Thus, although the excision of the scarred tissues is essential for the mobilization of the remnant external anal sphincter muscle for an overlapping repair, it is important not to clean off all the fibrous tissue on the remnant sphincter muscle2–4. Using the overlapping sphincteroplasty technique, 48% of patients maintained good fecal continence with a satisfaction rate of 85% at a mean follow-up of 84 months. Failure was attributed to mechanical dehiscence, progressive muscular atrophy or occult neuropathy9. Extensive perineal injuries resulting in anal sphincter disruption often require diversion and sphincter reconstruction. However, after clear tissue viability has been established and, there was no rectal laceration, the defect can be repaired primarily without diversion of the fecal stream as in this case10. A randomized trial that assessed the need for fecal diversion at the time of sphincteroplasty showed increased morbidity from a stoma with no difference in functional outcome or wound healing. Anal stenosis requiring repeated self-dilatation was a common complication from anal disuse11.
Table 1 -
Classification of perineal tear4
||Injury to perineal skin
||Injury to perineum involving perineal muscles but not involving the anal sphincters
||Injury to perineum involving the anal sphincter complex: 3a: <50% of external anal sphincter (EAS) thickness 3b: >50% EAS thickness 3c: both EAS and internal anal sphincter (IAS) involved
||Involves anal sphincter complex (EAS and IAS) and anorectal mucosa
A preoperative clinical assessment of traumatic anal injury in a resource-limited setting may suffice and correlates well with the intraoperative assessment. An overlapping sphincter repair without diversion is safe and effective in discrete anal sphincter injury.
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.
Sources of funding
E.P.W. is the main author and surgeon, and N.N. assisted with surgery.
Conflicts of interest disclosure
The authors declare that they have no financial conflict of interest with regard to the content of this report.
Research registration unique identifying number (UIN)
Professor M.N. Ngowe, Dean of Faculty of Medicine, University of Douala, Cameroon.
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