A Comprehensive Surgical Chapter for Postgraduate Students
Layers, landmarks, and why the posterior midline is the danger zone
Anal canal length: 3–4 cm from anal verge to anorectal junction (pelvic floor / puborectalis)
| Structure | Type | Notes |
|---|---|---|
| Internal Anal Sphincter (IAS) | Smooth muscle, involuntary | Distal 2/3 of canal; high-pressure zone — target of LIS |
| External Anal Sphincter (EAS) | Skeletal muscle, voluntary | 3 parts: subcutaneous, superficial, deep; surrounds IAS |
| Dentate / Pectinate Line | Landmark | 1.5 cm from verge; divides visceral (above) from somatic (below) innervation |
| Intersphincteric Groove | Surface landmark | Palpable groove between IAS & EAS — site of LIS incision |
| Anal Columns of Morgagni | Mucosal folds | 8–14 vertical folds above dentate line; bases form crypts & papillae |
Posterior commissure receives poorest blood supply from inferior rectal artery branches — making it uniquely vulnerable to ischaemia during sphincter spasm.
Anterior-posterior elongation of the anal orifice concentrates maximal shear force at the posterior commissure during defecation.
The puborectalis creates a forward pull, causing greater posterior stretch of the anal lining during passage of stool.
Posterior sphincter complex has significantly less subcutaneous fat cushioning compared to anterolateral portions.
Posterior commissure lies in a vascular watershed — elevated IAS pressure compresses capillaries, causing relative ischaemia that prevents healing.
The ischaemia-spasm vicious cycle and how LIS breaks it
Divides IAS → ↓ resting pressure → ↑ posterior blood flow → wound heals
| Mediator | Action | Drug Target |
|---|---|---|
| Nitric Oxide | IAS relaxation | GTN 0.2% |
| Acetylcholine | IAS contraction | Diltiazem |
| VIP | IAS relaxation (RAIR) | — |
| Botulinum Toxin | Blocks ACh at NMJ | Chemical sphincterotomy |
Causes, the Classical Triad, and histopathological features
| Category | Specific Causes |
|---|---|
| Primary / Idiopathic | Constipation, hard stools, straining — MOST COMMON |
| Primary | Diarrhoea, explosive loose motions (especially infants) |
| Obstetric | Childbirth trauma, episiotomy → anterior fissures in females |
| Inflammatory | Crohn's disease → atypical, multiple, irregular fissures |
| Infectious | TB, HIV, syphilis, herpes, CMV |
| Neoplastic | Squamous cell carcinoma, Bowen's disease |
| Iatrogenic | Post-haemorrhoidectomy, post-anal dilation |
| Haematological | Leukaemia, aplastic anaemia |
| Feature | Acute (<6 wks) | Chronic (>6 wks) |
|---|---|---|
| Edges | Soft, fresh | Indurated, fibrotic |
| Base | Red, granulation tissue | White IAS fibres visible |
| Sentinel Pile | Absent | Present |
| Hyp. Papilla | Absent | Present |
| Depth | Superficial | Deep to IAS |
| Healing | Often spontaneous | Rarely spontaneous |
| Treatment | Conservative | Pharmacological / LIS |
Indurated edges, pale/white base exposing horizontal IAS fibres. Posterior midline. Duration >6 weeks.
Oedematous skin tag at anal verge (distal end). Chronic inflammation + lymphatic obstruction. Pathognomonic of chronicity.
Enlarged fibrous papilla at dentate line (proximal end). Reactive hyperplasia from chronic irritation.
Ulcer + Pile (sentinel) + Spapilla (hypertrophied) = Complete Chronic Fissure Triad
Symptoms, examination findings, differentials, and red flags
"Internal sphincter length and thickness must be assessed with bidigital palpation: index finger inside the anal canal, thumb at the intersphincteric groove. This guides the extent of safe sphincterotomy and is the key to achieving 0% incontinence."
| Condition | Distinguishing Features |
|---|---|
| Haemorrhoids | Painless or mild ache; prolapsing tissue; no linear crack; painless dripping blood |
| Perianal Abscess | Constant throbbing pain; swelling; fever; no linear fissure visible |
| Fistula in Ano | Chronic discharge; external opening; probe-able tract; no linear crack |
| Crohn's Fissure | Atypical / lateral / multiple; irregular edges; biopsy: granulomas |
| Anal TB | Multiple / irregular; pale granulation; biopsy: caseating granulomas; AFB +ve |
| Anal SCC | Irregular, raised everted edges; not healing; biopsy mandatory |
| Primary Syphilis | Painless ulcer; inguinal lymphadenopathy; VDRL +ve; atypical location |
| Herpes Simplex | Multiple vesicles/ulcers; herpetiform; acute pain; viral culture +ve |
Conservative, pharmacological, and surgical options
High fibre diet + adequate hydration
Stool softeners (ispaghula, lactulose)
Sitz baths — warm water 3×/day
Avoidance of straining
Local anaesthetic ointment (lidocaine)
Releases Nitric Oxide → IAS relaxation → ↓ resting pressure by 30–40%
Applied 3×/day × 6–8 weeks
SE: Headache (25–30%), tachyphylaxis
Calcium channel blockade → smooth muscle relaxation of IAS → ↓ resting pressure
Fewer headaches than GTN; similar efficacy
Better tolerated long-term
Injected into IAS → blocks presynaptic ACh release → chemical sphincterotomy (3–6 months reversible effect). 20–25 units each side at 3 & 9 o'clock. Healing rate 60–80%. Can be repeated. Preferred in: elderly, patients with prior sphincter damage, or where incontinence risk is higher.
Dr. O.P. Bhandari's Modified Open Lateral Internal Sphincterotomy
| Technique | Approach | Incontinence Risk | Status |
|---|---|---|---|
| Open LIS (Parks) — Modified by Dr. Bhandari | Direct vision; intersphincteric groove | Lowest (~0–2%) | ✓ PREFERRED |
| Closed LIS | Blind technique; intraluminal knife | Low–Moderate (2–5%) | Acceptable |
| Posterior Midline (Watson-Cheyne) | Division at 6 o'clock | High + keyhole deformity | ✗ Abandoned |
| Anal Dilatation (Lord's) | Forceful 4-finger dilation | Very High (up to 20%) | ✗ Obsolete |
Index finger inside the anal canal + thumb at intersphincteric groove (3 or 9 o'clock). Palpate IAS between both digits. Assess length and thickness — guides safe extent of division.
Small longitudinal incision over the intersphincteric groove at 3 or 9 o'clock. Submucosal and intersphincteric planes delicately developed with the tip of a mosquito artery forceps.
IAS picked up with small Ellis forceps guided by index finger inside anal canal + thumb outside over the intersphincteric groove. IAS fibres divided up to the level of apex of the fissure only — not beyond.
Pressure applied to sphincterotomy wound using Babcock's forceps — holding full thickness for 2–5 minutes. Ensures secure haemostasis without suture-related complications.
Sphincterotomy wound left open OR closed with single stitch of 2-0 chromic catgut. Fissure granulation tissue curetted. Thickened fissure margins trimmed. Sentinel pile and hypertrophied papilla removed.
For wide fissures: mucosa at upper border of fissure mobilized and sutured by interrupted Matress sutures to anal verge using 2-0 chromic catgut. Accelerates healing and prevents stenosis.
Personal case series — 8 years, modified open LIS, Chittorgarh
Patients operated over 8 years — Modified Open LIS
Incontinence rate — no patient experienced flatus or stool incontinence
Patient developed intersphincteric low fistula → fistulotomy done → cured
Estimated cure rate — consistent with published LIS literature
| Parameter | Dr. Bhandari's Series | Published Literature (LIS) |
|---|---|---|
| Incontinence (any) | 0% (0/153) | 0–5% |
| Healing rate | ~95–98% | 92–98% |
| Recurrence rate | <2% | 1–8% |
| Fistula formation | 0.65% (1/153) | <1% |
| Technique | Modified Open LIS (bidigital) | Open or Closed LIS |
Of untreated fissure and of LIS surgery
| Complication | Incidence | Risk Level | Dr. Bhandari's Prevention |
|---|---|---|---|
| Bleeding (intraoperative / postoperative) | <2% | Low | Babcock pressure 2–5 min; open technique with direct vision |
| Incontinence — flatus | 1–5% (literature) | Moderate | Bidigital assessment; divide only to apex of fissure; 0% in 153 cases |
| Incontinence — stool | 0.1–0.4% | Low | Never exceed apex of fissure; open direct-vision technique |
| Infection / Cellulitis / Abscess | <1% | Low | Perioperative antibiotics; sitz baths post-op |
| Fistula Formation | <1% | Low | Careful intersphincteric plane dissection |
| Delayed Healing | 2–5% | Moderate | High fibre diet; sitz baths; curettage of granulation tissue |
| Anal Canal Stenosis / Scarring | <1% | Low | Mucosal advancement for wide fissures |
| Recurrent Fissure | 1–8% | Moderate |
Adequate LIS extent; post-op diet counselling; rule out secondary cause. Key principle: Recurrent fissure after LIS usually heals with medical treatment alone — because partial relaxation of the lower internal sphincter is already established from the prior sphincterotomy, restoring anodermal perfusion. If surgical re-intervention is ever required, contralateral (opposite side) LIS may be performed — but only if anal canal narrowing/stenosis is confirmed on bidigital assessment. Repeat ipsilateral sphincterotomy risks incontinence and should be avoided. |
| Chronic Pain | <2% | Low | Adequate anaesthesia; gentle technique; NSAIDs post-op |
Watch Dr. O.P. Bhandari perform fissure surgery — live operative recordings
Dr. O.P. Bhandari demonstrates his modified open lateral internal sphincterotomy technique. Step-by-step operative video including bidigital palpation, intersphincteric dissection, and IAS division.
Operative segment showing excision of sentinel pile, trimming of fissure margins, removal of hypertrophied anal papilla, and mucosal advancement for wide fissures.
Dr. Bhandari Piles Hospital, Chittorgarh, Rajasthan
Dr. Bhandari Piles Hospital
Chittorgarh, Rajasthan, India
Landline: 01472 241544
Mobile: +91 87640 01124
Piles Appointment (Secretary):
+91 94615 21485
MBBS · MS (General Surgery) · FAIS
Ex Professor of Surgery, PIMS Udaipur
Fissures occur at posterior midline — vascular watershed + mechanical shear
Ischaemia-spasm cycle is central to chronicity. LIS breaks this cycle.
Classical Triad: Ulcer + Pile (sentinel) + Spapilla
Atypical fissures (lateral, multiple, irregular) require BIOPSY
Open LIS under direct vision = gold standard with lowest incontinence risk
Dr. Bhandari: 153 cases, 0% incontinence — bidigital palpation is key