Chronic Fissure-in-Ano

Anatomy, Definition, Aetiopathogenesis & Classification

1.1 Definition and Anatomical Basis

An anal fissure (fissura ani) is a longitudinal, elliptical tear or ulcer in the squamous epithelium lining the anal canal, distal to the pectinate (dentate) line. When such a lesion persists beyond eight to twelve weeks without epithelialisation, it is classified as chronic. The distinction between acute and chronic fissure carries significant therapeutic implications: whereas acute fissures frequently resolve with conservative measures, chronic fissures have developed a self-perpetuating pathophysiology that almost always requires pharmacological or surgical sphincter relaxation for cure.

The classic triad of chronicity comprises: (1) a sentinel skin tag — an oedematous, hypertrophied fold of perianal skin at the anal verge, external to the fissure; (2) a hypertrophied anal papilla at the dentate line at the proximal limit of the fissure; and (3) visible horizontal fibres of the internal anal sphincter (IAS) forming the indurated floor of the ulcer. All three components are consequences of the underlying ischaemia and failure of mucosal regeneration.

1.2 Topographical Distribution and the Posterior Ischaemia Hypothesis

The overwhelming predilection of chronic fissures for the posterior midline (90–95% of cases) is explained by the relative hypoperfusion of the posterior anal canal. Doppler flowmetry studies by Schouten and colleagues (1994) confirmed that anodermalperfusion pressure at the posterior commissure was significantly lower than at any other circumferential position — a consequence of the terminal branching pattern of the inferior rectal arteries, which supplies the posterior commissure via long, poorly anastomosing end-vessels. The remaining fissures arise anteriorly — predominantly in multiparous women with obstetric injury to the anterior sphincter complex.

Lateral or atypical fissures (not in the anterior or posterior midline) are encountered in fewer than 1–2% of cases and should prompt investigation for Crohn's disease, tuberculosis, sexually transmitted infections (syphilis, herpes simplex, HIV), squamous cell carcinoma of the anal canal, or leukaemic infiltration. A biopsy is mandatory in all atypical fissures.

1.3 The Vicious Cycle of Chronicity

The pathophysiology forms a self-sustaining cycle: mucosal trauma (typically from a hard stool) creates a linear tear → the IAS responds with reflex hypertonia → elevated resting pressure reduces blood flow to the already poorly-perfused posterior commissure → tissue ischaemia prevents mucosal regeneration → the fissure persists → further defaecatory trauma perpetuates the injury. Without therapeutic interruption of this cycle, spontaneous healing of a chronic fissure is exceptional.

1.4 Classification

Historical Review: From Antiquity to the 20th Century

2.1 Ancient India — Sushruta Samhita (c. 600 BCE)

The earliest documented management of anorectal disease appears in the Sushruta Samhita, attributed to Sushruta of Varanasi (circa 600 BCE), the founding text of Ayurvedic surgery. Sushruta described a condition termed Parikartika — characterised by cutting-like pain of the anus, often accompanying diarrhoea — which closely corresponds to anal fissure. His management included warm avagaha sveda (medicated sitz baths) with neem, turmeric, and sesame oil decoctions; dietary regulation emphasising soft, lubricating foods and ghee; and medicated ghee-based pastes (sneha) applied topically. For refractory cases he described kshara sutra (alkali-medicated thread) and agnikarma (cautery) — the world's oldest recorded anorectal surgical procedures.

2.2 Ancient Egypt and Greece

The Ebers Papyrus (circa 1550 BCE) references rectal pain and prescribes suppositories of honey, fat, and herbal substances for anorectal ulceration. Hippocrates (460–370 BCE) in On Fistulae and Haemorrhoids described rectal ulceration and advocated gentle manual anal dilation — the world's first recorded dilation therapy — alongside warm fomentations and dietary management.

2.3 The 19th Century — Birth of Surgical Proctology

The modern surgical era begins with French gynaecologist Jean-Louis Récamier (1829), who introduced forcible anal dilation on the empirical observation that sphincter stretching relieves pain and promotes healing. The technique was later popularised by Peter Lord (1969) with four-finger dilation under general anaesthesia. Subsequent randomised studies revealed unacceptably high incontinence rates (11–39%) from uncontrolled sphincter disruption, leading to the procedure's widespread abandonment.

In 1886, Allingham described lateral subcutaneous sphincterotomy with scissors — a conceptual precursor to modern LIS — but it gained little adoption. The late 19th and early 20th century saw advocacy for posterior midline internal sphincterotomy (PMIS) — dividing the IAS at the fissure site itself — which persisted despite well-recognised complications including the keyhole deformity (posterior notch causing soiling and gas incontinence), impaired wound healing, and overall incontinence rates of 10–28%.

2.4 Eisenhammer's Conceptual Breakthrough (1951)

Eisenhammer (South Africa, 1951) provided the theoretical foundation for modern sphincterotomy by identifying the internal anal sphincter as the source of the hypertonia in chronic fissure and proposing its surgical correction as the curative mechanism — a paradigm that underpins all subsequent sphincterotomy development. His insight, that the IAS must be released rather than the fissure simply excised, shifted the entire therapeutic direction of the field.

Conservative Management

The cornerstone of initial management — effective for acute fissures and as adjunct therapy in chronic disease — is conservative (non-pharmacological) treatment aimed at softening stools, reducing defaecatory trauma, and transiently reducing sphincter pressure. While these measures rarely achieve long-term cure in established chronic fissure, they have an important role as first-line therapy and as peri-operative support.

3.1 Dietary and Stool Regulation

Increased dietary fibre intake (25–30 g/day) and fluid consumption (1.5–2 litres daily) produce softer, bulkier stools that reduce the shearing trauma of defaecation. Bulking agents — ispaghula husk (psyllium), methylcellulose, sterculia — are first-line adjuncts. Osmotic laxatives (lactulose, macrogol/polyethylene glycol) may be used when dietary modification is insufficient. These measures are safe for long-term use and should accompany all forms of specific therapy.

3.2 Sitz Baths

Warm sitz baths (37–40°C) for 15–20 minutes after defaecation are widely recommended and continue from the earliest Ayurvedic prescriptions to the present. The mechanism is a reflex reduction in IAS resting pressure (by 25–35% transiently) and increased local blood flow. Though the effect is transient, it reliably reduces pain after defaecation — often the most distressing symptom — and supports healing in mild-moderate disease.

3.3 Topical Local Anaesthetics and Emollients

Lidocaine 5% ointment or gel, applied before anticipated defaecation, reduces the severe agonising pain that typically causes patients to defer defaecation — itself perpetuating constipation and fissure trauma. Petroleum jelly and zinc oxide preparations protect healing epithelium from faecal contamination. None of these agents directly addresses the underlying IAS hypertonia.

Pharmacological (Chemical) Sphincterotomy

The pharmacological agents used in chronic fissure-in-ano act by reducing IAS resting tone — hence the term "chemical sphincterotomy." Unlike surgical sphincterotomy, their effects are reversible, which is their primary advantage and also the explanation for their high recurrence rates.

4.1 Glyceryl Trinitrate (GTN)

GTN 0.2–0.4% ointment, introduced by Loder et al. (1994), was the first pharmacological agent specifically evaluated for chronic fissure. As a nitric oxide (NO) donor, GTN causes smooth muscle relaxation in the IAS, reducing resting anal pressure by 25–35% for 2–4 hours per application. Multiple randomised controlled trials (RCTs) demonstrated healing rates of 46–68% versus 30–40% for placebo. The critical limitation is headache — a side effect occurring in 20–60% of patients — due to systemic nitrate absorption, which causes significant discontinuation. Recurrence upon cessation of treatment reaches 30–50% at two years, representing the fundamental limitation of reversible chemical sphincterotomy.

Attempts to improve tolerability through reduced concentration (0.1%), alternative delivery systems (suppository, transdermal patch), and topical agents restricted to the perianal region have achieved modest success. GTN remains the most extensively studied first-line agent for chronic fissure and is incorporated into the treatment algorithms of all major national colorectal and gastrointestinal societies.

4.2 Calcium Channel Blockers (CCBs)

Diltiazem 2% topical ointment and nifedipine 0.2–0.5% gel inhibit voltage-gated calcium channels in IAS smooth muscle fibres, reducing intracellular calcium availability and thereby lowering resting sphincter tone. Systematic reviews (Yiannakopoulou et al., 2012; Jonas et al., 2009) report healing rates of 65–75% with diltiazem, comparable to GTN but with a significantly more favourable side-effect profile — headache occurs in only 5–10% of patients, with occasional perianal dermatitis. Oral diltiazem (60 mg twice daily) is an alternative in patients unable to apply topical agents, though it carries more systemic side effects. Nifedipine gel demonstrates similar efficacy. CCBs are now considered a first-line alternative to GTN and are preferred in patients who experience significant GTN-related headache.

4.3 Botulinum Toxin Type A (BTA)

First proposed by Jost and Schimrigk (1993) and subsequently refined by multiple groups, BTA injection into the IAS produces reversible chemical denervation at the neuromuscular junction, reducing acetylcholine-mediated sphincter contraction for a period of 8–12 weeks. Standard dosing ranges from 15–30 units, typically divided between two injection sites in the IAS at the level of the dentate line. Healing rates in published series range from 60–80%. The reversibility of effect — while advantageous from a safety standpoint — means that 30–50% of patients experience recurrence within one to two years. Temporary, minor incontinence to flatus or liquid stool occurs in 7–20% of patients but resolves with return of IAS tone. The high cost of BTA relative to topical agents limits its widespread first-line use, though it occupies an important second-line role when pharmacological sphincterotomy with topical agents has failed.

Surgical Management: Evolution of Lateral Internal Sphincterotomy

Lateral internal sphincterotomy (LIS) is the gold-standard treatment for chronic fissure-in-ano that has failed conservative and pharmacological management. Its evolution spans seven decades of progressive refinement, driven by successive gains in anatomical understanding, manometric measurement, and critical analysis of outcomes.

5.1 Posterior Midline Internal Sphincterotomy — Abandoned

Dividing the IAS in the posterior midline at the fissure site — the earliest surgical approach — was plagued by the keyhole deformity (a posterior notch causing mucous soiling and gas incontinence), delayed wound healing averaging 8–12 weeks, and continence disturbance in 10–28% of patients. By the 1980s, posterior midline sphincterotomy had been comprehensively abandoned in favour of the lateral approach advocated by Notaras and Bennett.

5.2 Notaras Closed LIS (CLIS) — 1969

M. J. Notaras (1969) introduced lateral subcutaneous sphincterotomy: a cataract or tenotomy blade inserted through a stab incision at the intersphincteric groove and rotated to divide the IAS — all without direct visualisation. This "blind" technique offered rapid recovery, minimal wound morbidity, and became widely adopted. However, the critical limitation of CLIS is the absence of direct vision: the depth and extent of IAS division is estimated, not measured, leading to either under-division (leaving residual hypertonia → recurrence) or over-division (excessive IAS release → incontinence). Meta-analyses consistently demonstrate that CLIS carries a higher incontinence rate than open LIS — though individual expert hands may achieve excellent results.

5.3 Open LIS — Bennett & Goligher (1976)

Bennett and Goligher (1976) published open lateral internal sphincterotomy (OLIS): a formal radial incision at the intersphincteric groove, exposing the distal IAS under direct vision, followed by sharp division from the anal verge to the dentate line with scissors or diathermy. OLIS rapidly became the gold standard, with healing rates consistently above 95% and recurrence of 1–5%. The dominant concern was continence: major published series and meta-analyses report minor soiling or gas incontinence in 3–8%, and liquid incontinence in 1–2%.

Garcia-Aguilar et al. (1996) and subsequent investigators demonstrated that dividing the IAS only to the apex of the fissure (rather than to the dentate line) was sufficient for cure in most patients, with lower incontinence risk — the tailored or fissure-height LIS concept. Despite this advance, incontinence rates in large series remained above 2–3%, and the "fissure apex" as a division endpoint remained anatomically variable and subjectively judged.

5.4 Intraoperative Manometry-Guided LIS

Several groups proposed intraoperative anorectal manometry to guide the precise degree of IAS division — dividing until resting pressure falls to a target of 75–85 mmHg. While conceptually elegant, this approach added operative complexity, cost, and time, and required specialised equipment not available in most district-level surgical settings. Its adoption has therefore remained limited to academic centres.

5.5 Fissurectomy and Combined Approaches

Fissurectomy — excision of the chronic ulcer with its sentinel tag and hypertrophied papilla — has been evaluated both alone and in combination with LIS. Mousavi et al. (2009) in a prospective RCT found combined fissurectomy + LIS equivalent to LIS alone in healing, with no significant advantage. Fissurectomy alone, without sphincterotomy, fails in the majority of chronic fissures as it does not address the underlying IAS hypertonia. Most authorities now restrict fissurectomy to an optional concomitant procedure at the time of LIS in selected cases with large sentinel tags.

The Bhandari Modified Open Lateral Internal Sphincterotomy (MOLIS): Rationale and Operative Technique

6.1 Conceptual Foundation and Rationale

The Bhandari MOLIS was developed from a critical analysis of the principal source of incontinence in conventional open LIS: the imprecision of division to the dentate line as the endpoint. The dentate line, in the operative field of an anaesthetised, contracted sphincter, is a landmark that varies considerably in the surgeon's perception depending on anal canal length (which varies between sexes and individuals), the degree of mucosal prolapse, and the level of relaxation under anaesthesia.

The anatomical insight underlying MOLIS is that the lower one-third of the IAS — measured from the palpable anal verge as the external reference point — is both sufficient to achieve the manometric reduction needed for fissure healing and, crucially, is anatomically reproducible and consistent regardless of individual variation in anal canal length. By limiting division to this precisely identified segment — exposed and controlled with a haemostatic forceps before cutting — the surgeon eliminates the variability inherent in "dividing to the dentate line."

6.2 Step-by-Step Operative Technique

The MOLIS is performed under spinal anaesthesia in the left lateral position (or lithotomy). The operative steps are as follows:

6.3 Technical Advantages of MOLIS over Classical LIS

Prospective Series: 333 Consecutive Cases of Bhandari MOLIS (2016–2025)

7.1 Study Design

A prospective, single-surgeon, single-centre observational cohort study was conducted at Dr. Bhandari's surgical practice, Chittorgarh, Rajasthan, India, between January 2016 and December 2025. All 333 consecutive patients presenting with chronic fissure-in-ano (symptoms persisting for more than eight weeks with at least one feature of the classic triad of chronicity) who underwent MOLIS were included. Exclusion criteria comprised: atypical (lateral) fissures, confirmed Crohn's disease, HIV infection, tuberculosis, prior anorectal malignancy, or history of previous anorectal surgery. Continence assessment was performed using the structured clinical interview method at all follow-up visits.

7.2 Patient Demographics

7.3 Year-wise Enrolment

7.4 Outcomes

7.5 Novel MOLIS Applications

In addition to the standard MOLIS for chronic posterior or anterior midline fissure, the series documents two novel applications of the technique not previously described in the literature:

Bilateral MOLIS for severe anal canal stenosis (Case 314): A patient presenting with severe anal canal stenosis secondary to chronic bilateral fissure with circumferential scarring underwent bilateral MOLIS — simultaneous division of the lower one-third IAS at both the left lateral and right lateral positions — with complete relief of stenosis and maintained continence at follow-up.

Contralateral MOLIS as salvage for recurrent fissure after initial ipsilateral MOLIS (Cases 219 and 245): Two patients who had undergone left lateral MOLIS and subsequently developed recurrent fissure underwent right-lateral contralateral MOLIS as a salvage procedure, with complete healing and maintained continence. Both cases highlight the safety margin of the lower-one-third division endpoint.

7.6 Comparison with Published LIS Literature

Discussion

The management of chronic fissure-in-ano has followed a remarkable arc across 2,600 years — from the intuitive dietary and herbal prescriptions of Sushruta through the empirical dilation of Hippocrates and Récamier, the posterior sphincterotomy of the 20th century's early surgical proctology, to the precisely calibrated lateral internal sphincterotomy of the modern era. The central physiological insight — that IAS hypertonia creates a vicious cycle of ischaemia and impaired healing, which must be interrupted for cure — has remained constant since Eisenhammer's landmark contribution of 1951 and was quantified by Schouten's manometric studies of 1994.

The transition from uncontrolled manual dilation, through the elegant but visually imprecise closed LIS of Notaras, to the open LIS of Bennett and Goligher represented progressive moves toward visual control and reproducibility. Yet even the open LIS, despite its 95–99% healing rate, has consistently carried an incontinence rate of 3–8% in large published series and meta-analyses — a risk that, while modest, represents a clinically unacceptable outcome for a benign, non-life-threatening condition.

The Bhandari MOLIS represents the logical culmination of this arc of development: direct visual identification, precise haemostatic-forceps elevation, and sharp division of the anatomically identified lower one-third of the IAS — the minimum effective intervention calibrated to the therapeutic manometric target. By anchoring the division endpoint to the measurable anal verge (an anatomically consistent, palpable external reference) rather than the visually estimated dentate line (an internal landmark of variable perceived position under anaesthesia), MOLIS eliminates both principal mechanisms of post-sphincterotomy incontinence: over-division due to short anal canal length, and operator variability in endpoint estimation.

The achievement of zero incontinence across 333 consecutive cases over ten years is a result that has no precedent in the published LIS literature. Garg et al.'s 2013 systematic review and meta-analysis of 5,218 patients across all LIS techniques found a pooled long-term continence disturbance rate of 14% — including minor soiling, gas, and liquid incontinence — confirming the significance of this complication across the entire LIS literature. The MOLIS data challenge the assumption that some incontinence risk is an inherent and inevitable consequence of effective sphincterotomy.

Conclusion

Chronic fissure-in-ano has been the subject of clinical and surgical innovation for 2,600 years — from Sushruta's warm sitz baths and medicated ghee to the precisely instrumented modern sphincterotomy. The field has been relentlessly shaped by the dual therapeutic imperatives: definitive cure of the fissure, and preservation of anorectal continence. For most of the 20th and early 21st century, these imperatives existed in tension — the more effective the sphincterotomy, the greater the incontinence risk.

Pharmacological chemical sphincterotomy — GTN, diltiazem, nifedipine, and botulinum toxin — offers reversible, non-surgical options with acceptable healing rates in mild and moderate disease, but is limited by recurrence rates of 30–50% and modest long-term cure compared with surgery. Lateral internal sphincterotomy remains the gold standard for established chronic fissure, with 95–99% healing and 1–5% recurrence; its Achilles heel — an incontinence rate of 3–8% — has resisted elimination across half a century of refinement including tailored LIS and intraoperative manometry guidance.

The Modified Open Lateral Internal Sphincterotomy (MOLIS) developed by Dr. O. P. Bhandari achieves what classical LIS has sought but not consistently delivered: complete cure of chronic fissure-in-ano with absolute preservation of continence. The prospective 333-patient, 10-year series (January 2016–December 2025) demonstrates 100% healing and 0% incontinence of any grade or type — the best published results in the modern LIS literature and a genuine paradigmatic advance in the surgical management of this common condition.

The technique's defining innovation — precise visual identification and limited division of the anatomically measured lower one-third of the IAS under direct haemostatic-forceps control — provides a reproducible, anatomically logical endpoint that eliminates the incontinence risk inherent in less precisely defined sphincterotomy techniques. MOLIS is a procedure that any competent anorectal surgeon can learn and reproduce with appropriate training, and it is feasible in the district hospital setting without specialised equipment.

This series invites prospective multicentre validation and, in time, formal randomised comparison with classical open LIS. Should the zero-incontinence outcome be confirmed in such studies, a reappraisal of the standard of care for surgical management of chronic fissure-in-ano will be warranted, with Bhandari MOLIS as the preferred technique.

Ethical Approval and Consent to Participate: This study was conducted in accordance with institutional ethical standards and the principles of the Declaration of Helsinki. Informed consent was obtained from all patients (or their legal guardians, where applicable) prior to surgery and for inclusion of their de-identified clinical data in this series.

Funding: This study received no external funding, grant, or sponsorship from any pharmaceutical, commercial, or institutional source. The work was conducted as part of routine clinical practice at a self-funded, single-centre district-level surgical unit.

Conflict of Interest: The authors declare no conflict of interest, financial or otherwise, relating to this publication.

The authors record their sincere gratitude to Prof. N. K. Malpani, MS — Dr. Bhandari's PG teacher and Senior Surgical Adviser — whose scholarship, national stature, and endorsement as Main Author of this article have elevated its academic authority and contributed immeasurably to the formal recognition of the Bhandari MOLIS as a reproducible standard surgical technique. The authors further record their gratitude to Mr. Tara Chand, Appointment Manager, Dr. Bhandari Piles Hospital, Chittorgarh, who has maintained meticulous systematic long-term patient follow-up by telephone since 2012, without whom a 10-year prospective outcome series from a single district-level centre would not have been possible. The 333 patients who consented to participation in this study are gratefully acknowledged. Dr. Menal Bhandari, MD (Radiation Oncology, AIIMS Delhi), PGY4 Chief Resident, Loyola University Medical Center, Maywood, Illinois, USA, is acknowledged for contributions to the editorial and academic development of the GSP-SPCI portal.

Selected References

28 peer-reviewed and classical citations spanning 2,600 years of literature on chronic fissure-in-ano.

1. 01
   Sushruta. Sushruta Samhita, Chikitsa Sthana. Translated by Bhishagratna KL. Calcutta, 1911. (Original c. 600 BCE).
2. 02
   Ebers G. Papyrus Ebers: das hermetische Buch über die Arzneimittel der alten Ägypter. Leipzig, 1875. (Original c. 1550 BCE).
3. 03
   Hippocrates. On Fistulae and Haemorrhoids. In: Hippocratic Writings. Translated by Chadwick J, Mann WN. London: Penguin Classics, 1978.
4. 04
   Récamier JCA. Clinique d'Hôtel Dieu. Paris, 1829.
5. 05
   Allingham W. Fistula, Haemorrhoids, Painful Ulcer, Stricture, Prolapsus and Other Diseases of the Rectum. 4th ed. London: J. & A. Churchill, 1888.
6. 06
   Eisenhammer S. The surgical correction of chronic internal anal (sphincteric) contracture. S Afr Med J. 1951;25:486–489.
7. 07
   Gabriel WB. Principles and Practice of Rectal Surgery. 4th ed. London: HK Lewis, 1959.
8. 08
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9. 09
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21. 21
    Mousavi SR, Sharifi M, Mehdikhah Z. A comparison between the results of fissurectomy and lateral internal sphincterotomy in chronic anal fissure. J Gastrointest Surg. 2009;13:1279–1282.
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    Yiannakopoulou ECh, Nikiteas N, Perrea D, Tsigris C. Systematic review of chemical sphincterotomy agents for the treatment of chronic anal fissure. Int J Colorectal Dis. 2012;27:423–429.
24. 24
    Nelson RL, Manuel D, Gumienny C, et al. Non surgical therapy for anal fissure. Cochrane Database Syst Rev. 2012;(2):CD003431. [Updated 2023].
25. 25
    Garg P, Garg M, Menon GR. Long-term continence disturbance after lateral internal sphincterotomy for chronic anal fissure: a systematic review and meta-analysis. Colorectal Dis. 2013;15:e104–117.
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