Chapter 22 — Complete Anal Sphincter Complex Tear — Secondary Repair
Chapter 21 described obstetric sphincter injury, and its immediate repair at the time of delivery. This chapter covers a different situation: secondary repair. This is definitive surgery performed later, as a planned procedure. It suits a sphincter defect that was missed at the time of the original injury. It also suits a defect that has failed to heal well, despite an earlier repair attempt. This chapter gives the overlapping sphincteroplasty technique, the standard operation for this situation, in full technical detail.
22.1 What Is Secondary Sphincter Repair
Secondary sphincter repair is a planned, elective operation. It is performed after the original sphincter injury has already occurred. In most cases, the injury has already healed in an unsatisfactory position.
This differs from the primary repair described in Chapter 21, performed immediately at the time of delivery. Secondary repair is instead performed for a patient presenting later. This may be because the original injury was missed altogether, described as an occult injury in Chapter 21. It may also be because an earlier repair attempt has since broken down or stretched.
22.2 Indications
A confirmed anterior sphincter defect on endoanal ultrasound, described in Chapter 20, in a patient whose incontinence symptoms correlate with that defect.
A failed primary repair, where the original repair performed at the time of delivery has broken down, and symptoms have returned or never fully resolved.
A missed, or occult, obstetric sphincter injury, described in Chapter 21, presenting for the first time some months or years after delivery.
A cloaca, described in Chapter 21, needing formal reconstruction, discussed separately in Section 22.5 below, since it requires more than sphincter repair alone.
22.3 Pre-Operative Assessment
Endoanal ultrasound, described in Chapter 20, confirms the size and position of the sphincter defect, and is essential before planning surgery.
Anorectal manometry, described in Chapter 8, gives a baseline measurement of sphincter function, useful both for planning and for comparison after surgery.
Bowel preparation is arranged in the usual way before an operation in this area.
Careful counselling before surgery is essential. Overlapping sphincteroplasty improves continence in the great majority of patients, in the short term. Results are known to decline gradually over time, however, in a meaningful proportion of patients. This decline happens over
a period of years, rather than months. The patient should understand this realistically before consenting to surgery, rather than expecting a permanent, complete cure in every case.
22.4 The Overlapping Sphincteroplasty Technique
The patient is positioned in lithotomy, or in the prone jack-knife position, according to surgeon preference.
A curved incision is made anterior to the anus. The scarred tissue between the two separated ends of the external anal sphincter is then carefully identified and mobilised.
If the internal anal sphincter is also torn, it is identified and mobilised separately from the external sphincter, and repaired in its own distinct layer. This step is easily overlooked, if attention is focused only on the more visible external sphincter. Its omission is one of the most common reasons a repair underperforms.
The two ends of the external anal sphincter are then overlapped, rather than simply brought together end to end. They are secured in this overlapping, double-breasted fashion, with sutures. This overlapping technique is the key technical difference from the end-to-end repair. End-to- end repair is typically performed immediately, at the time of delivery, described in Chapter 21. Overlapping repair is associated with better functional outcomes when performed as a secondary, planned procedure.
The perineal body, the tissue between the vagina and the anus, is reconstructed as needed, and the skin is closed over the repair.
Antibiotic cover is given at the time of surgery. Stool softeners or laxatives are prescribed afterward, specifically to prevent straining. This is exactly the same approach described for primary repair in Chapter 21.
22.5 Reconstruction for Cloaca
Repair of a cloaca, described in Chapter 21, is more extensive than a straightforward sphincteroplasty. The missing rectovaginal septum, the tissue wall separating the rectum from the vagina, must also be reconstructed. This is in addition to the sphincter itself.
This reconstruction is performed in careful layers. A separate rectal wall and a separate vaginal wall are restored first. The sphincter repair described in Section 22.4 is then performed over this newly reconstructed layer.
In a particularly complex or previously failed case, interposition of healthy, well-vascularised tissue between the reconstructed layers is often used to support healing. A labial fat pad flap, known as a Martius flap, is a well-established option for this purpose. Interposition of the gracilis muscle, taken from the inner thigh, is reserved for the most complex or repeatedly failed reconstructions.
A temporary defunctioning stoma is often used to protect a complex cloaca reconstruction. It diverts stool away from the repair while it heals. It is reversed once healing is confirmed to be secure.
22.6 Special Situations
A recurrent defect after a previous sphincteroplasty may be considered for a repeat repair, though outcomes are generally less predictable than for a first attempt. Sacral nerve stimulation, described in Chapter 20, is a reasonable alternative to consider at this stage, rather than a further sphincter repair.
A cloaca needs the staged reconstructive approach described in Section 22.5, with careful consideration of a defunctioning stoma to protect the repair.
A patient with unrealistic expectations of a complete, permanent cure needs careful, honest counselling before surgery. Follow the discussion in Section 22.3. This avoids disappointment, even after a technically successful operation.
22.7 Complications
Wound infection or breakdown, a genuine risk given the location of the wound close to both the vagina and the anus.
Recurrence of the sphincter defect, and with it, recurrence of incontinence, which becomes more likely with each additional year following surgery.
Persistent, partial incontinence, even after a technically successful repair, particularly if a coexisting nerve injury, described in Chapter 20, was not identified beforehand.
Dyspareunia, related to scarring at the repair site.
22.8 Outcomes and Follow-Up
Most patients experience a genuine improvement in continence in the first one to two years after surgery. Functional results are known to decline gradually over the following years, in a meaningful proportion of patients. This is why the honest counselling described in Section 22.3 matters so much, before the operation is undertaken.
Long-term follow-up is needed, extending well beyond the immediate postoperative period. This identifies any gradual decline early. Further options, such as sacral nerve stimulation, can then be discussed promptly, if a decline occurs.
22.9 Common Mistakes to Avoid
Proceeding to surgery without endoanal ultrasound confirmation of the defect beforehand.
Performing a simple end-to-end repair, rather than the overlapping technique, in a secondary, planned setting.
Failing to identify and repair a torn internal sphincter separately from the external sphincter.
Attempting a straightforward sphincteroplasty in a patient with a true cloaca, without also reconstructing the missing rectovaginal septum.
Promising a complete, permanent cure without mentioning the realistic possibility of gradual functional decline over time.
22.10 Recording and Follow-Up
Record the defect confirmed on endoanal ultrasound, the technique performed, and the counselling given. For example: "Anterior sphincter defect confirmed on endoanal ultrasound, overlapping sphincteroplasty performed with separate internal sphincter repair, realistic outcome counselling given. Review in 6 weeks, then at 1 year to assess functional outcome." Arrange long-term follow-up specifically to identify any gradual decline in function. Do not simply discharge the patient once the wound has healed.
22.11 Why This Chapter Matters
Secondary sphincter repair offers genuine, meaningful improvement to a patient whose original injury was missed or poorly repaired. It is not a guaranteed, permanent cure, however. Honest counselling before surgery matters as much as the technique itself. The next chapter turns to a very different circumstance of anorectal injury: trauma arising from sexual assault, and the specific medico-legal responsibilities that accompany it.