Chapter 30 — Special Applications — Bilateral and Contralateral MOLIS
Chapter 29 described the standard MOLIS technique, for a first presentation of chronic anal fissure. This chapter covers two special applications of the same technique. The first is staged bilateral MOLIS, for severe anal canal stenosis, described fully in Chapter 18. The second is contralateral MOLIS, for fissure recurrence, given its full technical description here for the first time. This chapter also references illustrative cases from the author's own practice.
30.1 What Are These Special Applications
Standard MOLIS, described in Chapter 29, suits a first presentation of chronic anal fissure, at a single lateral site.
Two situations need a modification of this standard approach. Severe anal canal stenosis, of any cause, needs a more extensive release than a single site can safely provide. Fissure recurrence, after a previous sphincterotomy, needs a fresh operative site, rather than working through already-scarred tissue.
30.2 Staged Bilateral MOLIS for Severe Stenosis — Summary
Staged bilateral MOLIS is described in full technical detail in Chapter 18. This includes the sequence of division, the specific dilator sizes used for calibration, and the four-site escalation reserved for the most severe cases.
In summary, a left lateral division is performed first, and checked with a 23 millimetre and then a 27 millimetre dilator. A second, contralateral division is performed only if the 27 millimetre dilator fails to pass. Readers needing the complete technique should refer directly to Chapter 18.
Case 314, referenced in Chapter 18, illustrates this technique in the author's own practice.
Operative video: staged bilateral MOLIS for severe anal canal stenosis.
30.3 Contralateral MOLIS for Fissure Recurrence — Rationale
A fissure can recur after a standard sphincterotomy or a previous MOLIS. Re-operating at the original site carries a specific problem. The tissue at that site is already scarred from the first procedure. This scarring heals less predictably than fresh, unoperated tissue.
This same principle applies elsewhere in anorectal surgery. A secondary sphincter repair, described in Chapter 22, faces a comparable challenge when working through previously operated tissue.
Contralateral MOLIS avoids this problem directly, by performing the second procedure at a fresh site, on the opposite side of the anal canal from the original operation.
30.4 The Contralateral MOLIS Technique
Assess the recurrent fissure, and the site of the original operation, before planning the contralateral procedure.
If the original MOLIS was performed at the 3 o'clock position, the contralateral procedure is performed at the 9 o'clock position, or the reverse, depending on the original site.
The patient is positioned according to the standard sequence described in Chapter 3.
A small incision is made at the fresh, contralateral site, following the same principle described in Chapter 29.
The internal anal sphincter is delivered to the surface of the wound, exactly as in the standard MOLIS technique. This controlled, direct-vision approach applies equally at this fresh site.
Fibres of the corrugator cutis ani, described in Chapter 1, may again be encountered at this new site, and should be recognised and gently displaced, rather than injured.
The lower one-third of the internal anal sphincter is divided under direct vision, at this contralateral site.
The original operative site is left undisturbed. There is no need to re-explore or revise the earlier, already-healed scar.
Operative video: contralateral MOLIS for fissure recurrence.
30.5 Illustrative Cases
Cases 314, 219, and 245, from the author's own practice, illustrate these special applications.
Case 314, described in Chapter 18, illustrates staged bilateral MOLIS for severe anal canal stenosis.
Cases 219 and 245 illustrate contralateral MOLIS for fissure recurrence, performed following the technique described in Section 30.4.
Full individual case narratives are held in the author's own clinical records, and can be added to this chapter in future revisions as they become available for publication.
30.6 Special Situations
A patient with both severe stenosis and a coexisting fissure may need elements of both techniques described in this chapter, planned together rather than as entirely separate procedures.
A second recurrence, after a contralateral MOLIS has already been performed, needs careful individual reassessment, rather than a further sphincterotomy performed by default.
30.7 Complications
The complications of contralateral MOLIS are the same as those described for standard MOLIS in Chapter 29. These include bleeding, infection, and a theoretical risk of incontinence.
A further recurrence remains possible, even after a well-performed contralateral procedure, and should prompt the careful reassessment described in Section 30.6.
30.8 Common Mistakes to Avoid
Re-operating at the original, already-scarred site, rather than choosing a fresh contralateral position.
Proceeding directly to the four-site technique, rather than trying the staged bilateral approach first and escalating only if calibration shows it is needed.
Failing to check whether the original operative site and the new contralateral site are genuinely on opposite sides of the anal canal.
30.9 Recording and Follow-Up
Record the site of the original procedure, and the site chosen for the contralateral procedure. For example: "Fissure recurrence following MOLIS at 3 o'clock. Contralateral MOLIS performed at 9 o'clock, corrugator cutis ani identified and preserved. Original site left undisturbed. Review in 4 weeks." Arrange follow-up to confirm healing at the new site, and resolution of the recurrent fissure.
30.10 Why This Chapter Matters
These two special applications extend the same core principle described in Chapter 29, direct- vision division of the internal sphincter, to situations the standard technique alone cannot safely address. This chapter completes Part III of this manual. The appendices that follow provide supporting reference material, including the glossary of abbreviations used throughout.