Anal Fissure

Definition — a tear below the dentate line, staged by time and stigmata

An anal fissure is a longitudinal tear in anoderm below the dentate line and one of the commonest benign anorectal diseases.^[12] Stage it the way the global audit does: acute means symptoms under 6 weeks without sentinel pile; chronic means over 6 weeks or fibrotic edges with sentinel pile.^[88] In the 302-patient snapshot across 21 countries, 42% were acute and 58% chronic — and first contact split 78% conservative to 22% surgical, with 73% versus 88% resolved at 8 weeks.^[88] Trialists define chronic more strictly — visible sphincter fibres at the base, anal papillae, sentinel piles and indurated margins with symptoms chronic for at least 4 weeks — which is why trial healing rates run lower than clinic impressions.^[5]

Position is doctrine: the 623-patient acute cohort found 63.7% at 6 o'clock lithotomy, 21.0% at 12 o'clock, 4.5% at both, and 10.8% in atypical regions.^[89] The Russian 206-patient series concurs — posterior 84.9%, anterior 8.7%, combined 6.3% — with over 90% of all fissures posterior to the midline, where sphincter spasm produces ischaemia.^[92][6] Anything off-midline, multiple, or in that atypical tenth earns secondary-cause workup before any knife appears.^[89]

Pathophysiology — hypertonia of the whole sphincter, starving the anoderm

The primary abnormality is persistent hypertonia affecting the entire internal sphincter, unrelated to pain: computer-generated profiles measured mean resting pressure 120.5 mmHg in fissure patients against 82.6 in controls, with the high-pressure zone occupying 58% versus 48% of sphincter length — and elevation was not confined to the fissure site.^[66] Acute fissures grip harder than chronic ones (mean 106.4 and maximal 161.5 mmHg versus 92.4 and 117.5), and two-thirds of both carry ultraslow waves that raise hypertonicity, blunt relaxation and exaggerate after-contraction on rectal distension.^[55] Ultraslow-wave amplitude itself separates disease from health (31 versus 15 mmHg).^[66] The hypertensive-canal experiments close the loop: resting pressure 114.6 versus 72.5 mmHg in controls, with anal pain aggravated by defecation and unrelieved by analgesics.^[59]

Morphology follows function but does not mirror it: 91 to 92% of chronic fissures carry an abnormally thick internal sphincter (3.6 to 3.7 mm), yet thickness does not correlate with resting pressure — and neither clinical, manometric nor endosonographic features predicted who healed on GTN (42% at 8 weeks).^[60][61] Pressure does predict surgical fate: cured patients rested at 75.65 mmHg at two years against 112.85 in recurrent disease.^[38]

Presentation — pain first, bleeding second, stigmata third

Pain dominates (92.3 to 100% of presentations) with bleeding on defecation in 62 to 80%, plus pruritus, constipation and the sentinel pile association; the German review compresses it to sharp pain on defecation with or without blood.^{[12][82][91][96]} Acute pain starts higher (visual-analogue 8.8 versus 5.8 chronic) but responds better, falling to 0.47 versus 2.5 at six weeks on GTN-based conservative care.^[95] Chronic stigmata — sentinel pile, hypertrophied papilla, indurated margins, exposed fibres — mark the disease that rarely heals without intervention, especially beyond 12 months.^[5][38]

Differential — haemorrhoids, Crohn, sepsis and the low-pressure trap

Fissure pain is sharp and defecatory, with or without blood — take that history precisely before attributing anorectal pain to anything else.^[91][96] Then hunt secondary disease: about 45% of Crohn patients develop non-fistulizing perianal lesions including fissures, ulcers, strictures and tags, with deep ulcers and strictures marking the worse course.^[97] In paediatric-onset Crohn (1,005 patients), anal ulceration stood at 25.6% at diagnosis with 44.0% cumulative incidence at 10 years — and doubled the risk of fistulizing evolution (hazard ratio 2.00) regardless of biologic era.^[99] Crohn fissures resist conventional treatment, and surgery in that setting carries extra complications and is reserved for refractory disease.^[98][97]

The subtlest trap is the low-pressure fissure: 31% of chronic fissures are low-pressure (anterior disease rests lower at 66 versus 83 mmHg), and 78% of them respond to botox with contraction or nothing versus 30% of high-pressure fissures — physiologically different disease where tone-lowering logic fails.^[56]

Assessment — examine everyone, instrument the failures

History plus examination plus proctoscopy makes the diagnosis; further imaging is for selected cases only.^[72] After first-line failure, endoanal ultrasound and manometry guide the choice between sphincterotomy and fissurectomy-with-flap.^[43] Never trust the finger for tone: 55% of chronic fissures had normal and 8% low resting pressure on manometry, yet surgeons judged only 13% non-hypertonic — 93% sensitive for high pressure but 16% specific for normal-or-low disease — so treat all primarily medically and manometer selectively before cutting.^[63]

Conservative care — diet, behaviour and sitz baths win the acute phase

Acute fissure care is medical therapy with dietary and behavioural norms — the SIUCP first line — while chronic disease steps up to topical nifedipine-lidocaine or nitrates.^[43] The Danish review agrees: acute fissures are effectively treated and prevented conservatively, chronic ones typically need medical or surgical therapy.^[94] The combination that earns the viva point is diet plus 0.2% nitroglycerin: epithelialization in 10.5 days, superior to either alone or hygiene, with the strongest pain reduction from day 3 and complete prevention of chronicity in 120 acute patients.^[1] In the Russian series, antispasmodics plus GTN healed 77.8% of acute fissures without any surgery.^[92]

Time is the predictor: healing on bulking agents, sitz baths and 0.2% GTN falls from 100% under one month of symptoms to 33.3% beyond six months (acute 80% versus chronic 40%).^[95] Sitz baths hold roughly 80% recovery with real analgesic properties and no reported side effects — but against sphincterotomy their healing rate is frankly inferior, with incontinence the surgical price.^[91]

GTN versus calcium-channel blockers — the first-line duel

Cochrane sets the floor: GTN heals 48.9% against 35.5% placebo — marginally but significantly better — with late recurrence common, across 75 trials, 5,031 participants and 17 agents.^[17] The 148-trial GRADE review confirms sustained-cure superiority over control (odds ratio 0.68) on very poor quality evidence — and names LIS-versus-any-medical-therapy (odds ratio 0.12) the only high-quality comparison in the field.^[34]

Diltiazem matches GTN for healing (relative risk 1.04, not significant) and beats it where patients feel the difference: headache (relative risk 0.15) and late recurrence (relative risk 0.51) — first-line non-operative therapy on tolerability.^[10] The long-term meta-analysis agrees (diltiazem over GTN 1.16 with adverse effects 0.13), with nifedipine crushing lidocaine for healing (4.53) and recurrence (0.18).^[5] State the GRADE honestly: high-certainty more headache on GTN than placebo (2.73) and than diltiazem (6.88), with only low-certainty healing benefit over placebo (1.96).^[9]

Topical ladder — nifedipine ranked first, adjuncts priced honestly

The 22-trial, 1,770-patient network ranks them: nifedipine highest healing, then diltiazem and minoxidil, lidocaine lowest; diltiazem lowest recurrence and best pain relief; GTN the most adverse effects.^[2] Two head-to-heads sharpen it: nifedipine beat diltiazem for acute remission (77.4 versus 54%) with earlier pain relief and equal six-month relapse (16.3 versus 21.4%), while the double-blind trial found them comparable (70.9 versus 67.3% healed; REALISE collapsing 17.7 to 5.3 versus 16.3 to 5.8).^[16][14]

Adjuncts, each with its number: minoxidil 5% beat GTN for healing (76.7 versus 46.9%, faster, adverse events 6.6 versus 40.6%) though GTN left lower post-treatment pain scores.^[13] Tocopherol beat GTN for pain decline (67.1 versus 56.2 mm) and recurrence (2.9 versus 13.2%).^[8] Propionibacterium gel equalled GTN for healing with far fewer adverse events (63.8 versus 3.4% at visit one, headache dominant) and lower cost.^[4] Platelet-rich plasma accelerated epithelialization (pain decline 5.7 versus 4.1 points; epithelialization gap 56.2%) and PRP-plus-topical healed 96 versus 66% at six months with bleeding 4 versus 32% — superior in chronic, not acute, disease.^[11][90] Metronidazole-plus-GTN beat GTN alone for acute healing (68.1 versus 23.5% complete at three weeks), and metronidazole-plus-lidocaine beat lidocaine alone (86 versus 56% recovered).^[6][93] The nifedipine/lidocaine/betamethasone combo gel improved healing, pain, bleeding, discharge and itch without side effects in acute and chronic disease.^[24] Topical sildenafil cut resting pressure 18% within three minutes with no headaches — physiology demonstrated, healing unclaimed.^[65]

Botulinum toxin — low dose, right clock-face, honest recurrence

Dosing doctrine comes from two syntheses: low-dose botox is optimal — out-of-fissure injection improves short-term healing while each-side-of-fissure injection tends to cut long-term recurrence (27 trials, 1,880 patients, moderate evidence) — and each dose increment slightly worsens healing, incontinence and recurrence.^[19][76] Technique details examiners probe: 6-and-12 o'clock injection beats 3-and-9 for early pain and fewer thrombosed haemorrhoids with equal twelve-week healing, and unilateral 100-unit injection matches bilateral 50-plus-50 for healing and pain with better early continence.^[22][25]

Combinations disappoint more than they deliver: botox-plus-low-dose-GTN changed nothing (30 versus 33% at six weeks; 50 versus 57% at twelve) while 58% suffered moderate-or-severe GTN headaches — single-agent botox better tolerated.^[29] The Pakistani trial disagrees (pain 3.06 versus 4.67; healing 90.9 versus 69.7% at four weeks with added GTN) — small trials with conflicting answers, headache the certain cost either way.^[3][29] Botox-plus-diltiazem did not beat botox alone (52 versus 36.7% per-protocol, not significant) with 30% transient incontinence and 83.3% recurrence at ten years.^[21] Against nitrates (six trials, 393 patients): no healing or recurrence difference, more transient incontinence on botox (odds ratio 2.53) but fewer total side effects (0.12) and headaches (0.10) — warn every botox patient about transient leakage.^[26]

Against surgery, botox loses on durability and wins on continence: the seven-trial meta-analysis (489 patients) gives LIS higher healing and higher incontinence with significantly lower recurrence, and the 50-patient randomised trial found two-month healing 44% versus 88% (equal by three months), higher botox recurrence, and 4% final LIS incontinence.^[30][32] The duration qualifier matters: botox-plus-diltiazem matched partial LIS at 100% each for fissures under twelve months, but lost 23% to 86% beyond a year.^[28]

LIS — the definitive operation, priced by technique

Surgery and conservative care are complementary strategies, not rivals — but for refractory disease, LIS provides the durable answer with high success rates.^[15] The head-to-heads: LIS beat GTN for six-week healing (85.1 versus 55.3%) and six-month healing (89.4 versus 68.1%), with transient flatus 8.5% and liquid leakage 6.4% against GTN headache 61.7% and recurrence 34%.^[7] The 550-patient four-arm trial found 37.3% of GTN patients still unhealed at two months, with LIS the best response — the gold standard when recurrence must be avoided.^[12]

Networks agree at every level: 69 trials put LIS top for healing at all time points with botox equalling medical therapy, flaps matching LIS, and LIS carrying the most incontinence.^[20] The 44-trial network measured it — healing 93.1 (LIS), 84.4 (dilatation), 79.8 (fissurectomy/anoplasty), 62.6 (botox), 58.6% (non-invasive), against incontinence 9.4, 18.2, 4.9, 4.1 and 3.0%.^[27] The nine-trial review at eight weeks: LIS 95.13, botox 66.7, nitrates 63.8, diltiazem 52.3, minoxidil 50% — with recurrence lowest on LIS (6.9%) and highest on botox (41.7%) at the price of permanent incontinence risk.^[23]

Open versus closed is settled as a draw with caveats: the eight-trial meta-analysis (1,035 patients) found 90.2% healing, 3.7% recurrence and 8.9% incontinence overall, with closed trending more recurrence (relative risk 1.73, not significant) and less incontinence (0.60).^[33] The Karachi trial favours closed on day five (4.3 versus 21.3%), and the 136-patient trial found less pain and shorter stay with closed surgery.^[35][36] But durability erases the gap: 92.5 versus 90% healed at two years with 5 versus 2.5% mild incontinence, and 96% healed at six weeks with 6.8% any new and 4.1% major incontinence at one year regardless of technique.^[38][39] Cochrane concurs — open and closed equally efficacious — and manual anal stretch should be abandoned in adults, losing to sphincterotomy on both persistence and incontinence.^[37][41]

Fine print that wins marks: primary closure of the LIS wound halves healing time (15.05 versus 33.94 days) without changing wound complications.^[40] Redo contralateral LIS for surgically recurrent fissure heals 98% with 4% minor incontinence and 9.7-out-of-10 satisfaction over twelve-year mean follow-up.^[82] The 422-patient high-volume cohort reached 97.5% pain-free and continent at two months with no long-term recurrence and normal continence — experience and standardization are part of the operation.^[71] Total sphincterotomy healed all 164 with 96% satisfaction but five persistent flatus-or-soiling cases — the historical warning against maximal division.^[69]

Tailored extent — calibrate the cut, especially in women

Divide by manometry, not habit: 20% of the sphincter for mild hypertonia (50 to 60 mmHg), 40% moderate, 60% severe — curing 97.6% of 388 with 0.4% gas incontinence.^[62] The prospective 3D-ultrasound rule draws the line under 25% of total sphincter length, above which continence scores deteriorate.^[83] The partial-versus-complete trial proves the principle: pain 20 versus 70%, bleeding 25 versus 55% favouring fissure-apex-limited division.^[77] In women, the minimal series (20% length, 32 patients) reached 93.3% success at six months and 100% at twelve with Cleveland score zero throughout.^[81] The ultra-modified operation healed faster with less incontinence and higher satisfaction than closed LIS at one and two years.^[80] Two modifiers to voice: parous women start from lower sphincter pressures, so shorten the cut — and conventional LIS still beat tailored surgery for pain and satisfaction with equal continence in the 132-patient trial, so tailor to physiology, not fashion.^[78][85]

Sphincter-sparing surgery — flaps for the incontinence-averse and the normotensive

After first-line failure the SIUCP choice is LIS or fissurectomy-with-flap, guided by findings plus ultrasound and manometry.^[43] The German 481-patient series claims flap as first-line surgery: feasible in 94.6%, symptom-free 53.2% and healed 47.9% at one month, with 0.9% early complications, 0.2% incontinence and 3.3% recurrence.^[48] The Shanghai randomised trial proves flap beats bare fissurectomy: healing in 17.22 versus 21.24 days with less pain and bleeding and no incontinence signal.^[54] Tailoring LIS to the fissure apex under a dermal flap heals faster with less pain, analgesia and soiling than conventional LIS to the dentate line.^[52]

The normotensive doctrine is the viva jewel: a normotonic sphincter is present in 20 to 40% of chronic posterior fissures — and fissurectomy-plus-V-Y anoplasty heals 100% within 40 days with zero de novo incontinence and unchanged manometry, because sphincterotomy is illogical without hypertonia.^[46] Anterior disease without hypertonia holds the same at five years with no new incontinence, and resistant normotensive disease heals within 30 days with resting pressure unchanged.^[49][57] Hypertonic disease needs pharmacological partnership: V-Y flap plus chemical sphincterotomy normalized pressures and ultraslow waves to healthy levels at 24 months with only three transient low-grade incontinence cases.^[44] Adding botox beat flap alone (100 versus 80% healed at forty days), nifedipine-lidocaine backing healed all thirty with zero de novo incontinence, and botox backing held five-year manometry equal to healthy controls.^[45][50][51] The vertical non-full-thickness midline variant healed 96% with incontinence scores falling to zero, and the 48-patient flap series cut pain from the first defecation with only four late recurrences.^[42][31] Anterior hypertonic disease healed completely within 30 days with pressure reduction, and post-flap manometry drifts toward normal by six to twelve months with continence preserved.^[58][53]

Two honest alternatives: subcutaneous fissurotomy — laying open the sentinel tract without any sphincterotomy — needed repeat surgery in only 1.8% of 109 with no continence change, but it remains a single-centre novel claim.^[84] Anterior levatorplasty matched sphincterotomy for healing and satisfaction in women with rectocele while lengthening the canal at the price of more early pain — an incontinence-avoiding option that addresses aetiology.^[86]

Consent and continence — quote the lifetime numbers

The 585-patient survey (83% response, mean 72 months) is the consent backbone: 96% healed by three weeks, 8% recurrent (two-thirds rescued medically), ever-incontinent 45% — women 53.4 versus men 33.3 — comprising flatus 31, soiling 39 and gross 23%, settling to flatus 6, soiling 8 and solid-stool 1% at survey, with only 3% saying quality of life was ever affected and 98% satisfied.^[70] Contrast the flap at six to eight years: mild incontinence 47.6% after LIS versus 5.8% after dermal-flap coverage with equal healing.^[67] After any internal-sphincter division in women, 46% report some incontinence, with ultrasound gap length the functional correlate.^[79]

Mechanism matters for the viva: incontinent versus continent post-sphincterotomy patients differ in resting physiology, sphincter asymmetry and inhibitory-reflex latency — without any MRI-detectable morphologic difference — so leakage is not proof of surgical misadventure, and its long-term course is genuinely unknown.^[87] Preoperative predictors of trouble are lower resting pressure in future-incontinent patients (55 versus 80.7 mmHg), excessive section, perineal descent and advanced age; recurrence (10.2%) traces to incomplete section.^[64][68] Set the review-grade band: incontinence after LIS runs 3.4 to 4.4% across 148-trial subgroups, 8.9% in the open-versus-closed meta-analysis, up to 10% mostly flatus — then individualize by sex, parity, pressure and extent.^{[34][33][31][79][78]}

Special populations — pregnancy conservative, Crohn restrained

Pregnancy concentrates proctological disease in 45 to 68% — fissures rank second after haemorrhoids, driven by constipation past 60% — so regulate stool, add analgesia and topical ointments first, reserving surgery for refractory cases only.^[72] Dublin's 258-patient cohort timed onset 15/30/55% across trimesters with 45% symptomatic antenatally, 77% managed conservatively and 78% medically with a single operation, 45% resolving within days — while 64% self-diagnosed without guidance, so prescribe fibre, fluids and bath salts explicitly.^[73]

Crohn fissures demand restraint: conventional treatments fail with active perianal disease, and surgery carries extra complications — the adipose-tissue pilot (56% complete healing, defecation pain 7.5 falling to 2.75, no complications in nine patients) is promising but controlled trials must follow.^[98][97] Remember the ulceration trajectory: half of paediatric-onset patients ulcerate within a decade, doubling fistulizing risk — these are medical diseases with surgical complications, not surgical diseases awaiting a cut.^[99]

Practice close — the SIUCP ladder and the investigational edge

Real-world care is heterogeneous — 78% conservative-first, 22% surgical, 73 versus 88% resolved — which is exactly what the ladder resolves.^[88] Recite it: acute disease gets diet and behaviour; chronic first-line gets topical 0.3% nifedipine plus 1.5% lidocaine or nitrates, optionally with film-forming healing ointments such as Propionibacterium gel; failure gets LIS or fissurectomy-with-flap guided by findings plus ultrasound or manometry.^[43] The ASCRS 2023 clinical practice guideline is the parallel American reference.^[74] Percutaneous tibial nerve stimulation (87.5 versus 65.0% healing, zero headache dropouts against 15% on GTN) stays investigational — unblinded, small, possibly needle-placebo.^[75] And anal stretch stays abandoned.^[37]

Revision summary

Tear below the dentate line; acute under six weeks, chronic with stigmata; posterior in nine of ten with a tenth atypical and secondary. Whole-sphincter hypertonia starves the anoderm; a third are normotensive and must never meet a blade unmeasured. Diet plus nitroglycerin wins acute disease; nifedipine ranks first topically with diltiazem kindest for pain; GTN heals but headaches quit. Low-dose botox at 6-and-12 heals half with transient leakage warned. LIS heals 93-plus percent — open equals closed, extent under 25%, partial beats complete, redo rescues 98%. Flaps equal LIS healing with minimal leakage and own normotensive disease. Lifetime leakage 45% ever, single digits lasting, women more. Pregnancy conservative; Crohn medical. Ladder: SIUCP by heart, ASCRS 2023 beside it.^{[88][66][56][1][2][10][19][20][83][67][70][72][97][43]}

acute trial — remission 77.4% vs 54% (p=0.01) with earlier pain relief and equal 6-month relapse (16.3 vs 21.4%) (PMID 37546514); double-blind trial — healing 70.9% vs 67.3% comparable with REALISE collapsing 17.7 to 5.3 versus 16.3 to 5.8 (PMID 41989019).^[16][14] Settle open-versus-closed four ways: 8-RCT meta (n=1035) — overall healing 90.2%, recurrence 3.7%, incontinence 8.9%, with closed trending more recurrence (RR 1.73, ns) and less incontinence (RR 0.60) (PMID 38017243); Karachi RCT (n=94) — day-5 incontinence 4.3% closed vs 21.3% open (p=0.027) (PMID 27004344); 136-patient RCT — closed less pain and shorter stay (PMID 24637183); but the 80-patient local-anaesthetic RCT (2-year healing 92.5 vs 90, incontinence 5 vs 2.5 mild) and the 79-patient Wexner RCT (96% healed at 6 weeks, 6.8% any new incontinence and 4.1% major at 52 weeks, technique ns) find no durable difference — Cochrane (27 studies, 2056 patients) concurs open and closed are equally efficacious and manual stretch should be abandoned (PMIDs 15325604, 15129311, 22071803; 1999 meta PMID 10566530).^[35]

Position the adjuncts with their numbers: minoxidil 5% beats GTN for healing (76.7 vs 46.9%, faster by 1.2 weeks, adverse 6.6 vs 40.6%) though GTN wins post-treatment pain (PMID 32028023); tocopherol beats GTN for pain decline (67.1 vs 56.2 mm) and recurrence (2.9 vs 13.2%) (PMID 34803148); Propionibacterium gel equals GTN for healing with fewer adverse events (63.8 vs 3.4% at visit 1) and lower cost (PMID 37029603); PRP accelerates epithelialization (DCR trial pain decline 5.7 vs 4.1, epithelialization gap 56.2%) and PRP-plus-topical heals 96 vs 66% at 6 months with bleeding 4 vs 32%, superior in chronic but not acute disease (PMIDs 33399410, 37340514); metronidazole-plus-GTN beats GTN alone for acute healing (68.1 vs 23.5% complete at 3 weeks) (PMID 36440295) and metronidazole-plus-lidocaine beats lidocaine alone (86 vs 56% recovery) (PMID 30248299); the nifedipine/lidocaine/betamethasone combo gel improved healing, pain, bleeding, discharge and itch without side effects (PMID 30430875); topical sildenafil cut resting pressure 18% within 3 minutes with no headaches — physiology only, not a healing claim (PMID 15073662).^[82]

Botox-plus-GTN doubled nothing in the small NZ trial (30 versus 33% at 6 weeks, 50 versus 57% at 12 weeks) while 58% suffered moderate or severe GTN headaches — single-agent botox is better tolerated.^[86] Incontinent versus continent post-sphincterotomy patients differ in resting and vector-volume physiology and sphincter asymmetry (+6.7 versus -2.8%) and rectoanal inhibitory reflex latency, without any MRI-detectable morphologic difference — so leakage is not produced by a visible defect.^[87]

References99ShowHide

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