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. 2014 Nov 12;2014:0407.

Anal fissure (chronic)

Richard L Nelson 1
PMCID: PMC4229958  PMID: 25391392

Abstract

Introduction

Anal fissures are a common cause of anal pain during, and for 1 to 2 hours after, defecation. The cause is not fully understood, but low intake of dietary fibre may be a risk factor.

Methods and outcomes

We conducted a systematic review and aimed to answer the following clinical question: What are the effects of surgical treatments for chronic anal fissure? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2014 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

Results

We found nine studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

Conclusions

In this systematic review, we present information relating to the effectiveness and safety of the following interventions: anal advancement flap, anal stretch/dilation, and internal anal sphincterotomy.

Key Points

Chronic anal fissures typically occur in the midline, with visible sphincter fibres at the fissure base, anal papillae, sentinel piles, and indurated margins.

  • Anal fissures are a common cause of anal pain during, and for 1 to 2 hours after, defecation. The cause is not fully understood, but low intake of dietary fibre may be a risk factor.

  • Chronic fissures typically have a cyclical history of intermittent healing and recurrence, but about 35% will eventually heal, at least temporarily, without intervention.

  • Atypical features, such as multiple, large, or irregular fissures, or those not in the midline, may indicate underlying malignancy, sexually transmitted infections, inflammatory bowel disease, or trauma.

Internal anal sphincterotomy is more effective than medical therapy for chronic anal fissure in adults. It improves fissure healing compared with treatment with nitric oxide donors (topical glyceryl trinitrate, topical isosorbide dinitrate), botulinum A toxin-haemagglutinin complex, and calcium channel blockers (nifedipine, diltiazem).

  • Internal anal sphincterotomy also increases fissure healing compared with digital anal stretch, and anal stretch is more likely to cause flatus incontinence. One small RCT found limited evidence that controlled anal dilation may be equivalent to sphincterotomy in fissure healing, with negligible incontinence risk.

  • We don't know whether anal dilation is more effective than topical glyceryl trinitrate at reducing the proportion of people with anal fissure.

  • We don’t know whether internal anal sphincterotomy is better or worse than anal advancement flap in improving fissure healing.

  • Open partial lateral internal anal sphincterotomy may be equivalent to closed partial internal anal sphincterotomy in fissure healing.

  • Longer internal anal sphincter division (to the dentate line, as opposed to the fissure apex only) may be more effective at reducing anal fissure.

The risk of minor flatus or faecal incontinence is greater with internal anal sphincterotomy than with botulinum toxin. Topical glyceryl trinitrate increases the risk of headache compared with internal anal sphincterotomy.

Post-surgical faecal incontinence may be confused with post-surgical leakage (a short-term adverse effect). Confirming post-surgical leakage requires long-term follow-up (at least 12 months).

Clinical context

About this condition

Definition

An anal fissure is an ulcer or tear in the squamous epithelium of the distal anal canal, usually in the posterior midline. People with an anal fissure usually experience pain during defecation and for 1 to 2 hours afterwards. Multiple fissures and large, irregular, or large and irregular fissures, or fissures off the midline are considered atypical. Atypical fissures may be caused by malignancy, chemotherapy, STIs, inflammatory bowel disease, or other traumas. Treatments for atypical fissures are not included in this review. It is not clear what the best treatment strategy is in people who present with a painless anal fissure and in whom an atypical aetiology has been ruled out. Acute anal fissures have sharply demarcated, fresh mucosal edges, often with granulation tissue at the base. Acute fissures are believed to often heal spontaneously. Chronic anal fissures Fissures persisting for longer than 4 weeks, or recurrent fissures, are generally defined as chronic. Chronic anal fissures have distinct anatomical features, such as visible sphincter fibres at the fissure base, anal papillae, sentinel piles, and indurated margins. Most published studies only require the presence of one of these signs or symptoms of chronicity to classify a fissure as chronic. This review deals only with chronic anal fissures.

Incidence/ Prevalence

Anal fissures are a common cause of anal pain in all age groups, but we found no reliable evidence about precise incidence.

Aetiology/ Risk factors

The cause of anal fissure is not fully understood. Low intake of dietary fibre may be a risk factor for the development of acute anal fissure. People with anal fissure often have raised resting anal canal pressures with anal spasm, which may give rise to ischaemia.

Prognosis

Chronic anal fissure typically has a cyclical pain history, with intermittent healing and then recurrence. One systematic review found healing rates of about 35% without intervention, depending on the length of study follow-up.

Aims of intervention

To relieve symptoms (pain, bleeding, and irritation); to heal the fissure; to minimise adverse effects of treatment.

Outcomes

Fissure healing, persistence, or recurrence proportion of people with fissure healing, persistence, or fissure recurrence; Symptom improvement symptom score for intensity of symptoms of pain, bleeding, and irritation (typically a linear visual analogue scale that consists of an unmarked 100-mm horizontal line, the left end of which represents absence of symptoms, and the right end of which represents the worst symptoms imaginable; a vertical mark is made across this line by the person with the fissure); Adverse effects. Studies of treatments for anal fissure should have reasonable follow-up periods because late recurrence after treatment is very common (>50% in some studies). Few published studies have sufficient follow-up to determine their efficacy in preventing recurrence of chronic anal fissure. Faecal incontinence requires long-term follow-up (at least 12 months); ascertainment is complicated by confusion of post-surgical leakage (short-term adverse effect) with faecal incontinence. Headache is a common adverse effect of nitric oxide donor treatment.

Methods

Clinical Evidence search and appraisal January 2014. The following databases were used to identify studies for this systematic review: Medline 1966 to January 2014, Embase 1980 to January 2014, and The Cochrane Database of Systematic Reviews, issue 1, 2014 (1966 to date of issue). Additional searches were carried out in the Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment (HTA) database. We also searched for retractions of studies included in the review. An information specialist identified titles and abstracts in an initial search, which an evidence scanner then assessed against predefined criteria. An evidence analyst then assessed full texts for potentially relevant studies against predefined criteria. An expert contributor was consulted on studies selected for inclusion. An evidence analyst then extracted all data relevant to the review. Study design criteria for inclusion in this review were: published RCTs and systematic reviews of RCTs in the English language,any level of blinding, containing at least 20 individuals (at least 10 in each arm), of whom at least 80% were followed up. There was no minimum length of follow-up but outcomes at 1 year were preferentially reported. We included RCTs and systematic reviews of RCTs where harms of an included intervention were assessed, applying the same study design criteria for inclusion as we did for benefits. In addition, we use a regular surveillance protocol to capture harms alerts from organisations such as the FDA and the MHRA, which are added to the reviews as required. To aid readability of the numerical data in our reviews, we round many percentages to the nearest whole number. Readers should be aware of this when relating percentages to summary statistics such as relative risks (RRs) and odds ratios (ORs). We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table). The categorisation of the quality of the evidence (high, moderate, low, or very low) reflects the quality of evidence available for our chosen outcomes in our defined populations of interest. These categorisations are not necessarily a reflection of the overall methodological quality of any individual study, because the Clinical Evidence population and outcome of choice may represent only a small subset of the total outcomes reported, and population included, in any individual trial. For further details of how we perform the GRADE evaluation and the scoring system we use, please see our website (www.clinicalevidence.com).

Table.

GRADE Evaluation of interventions for Anal fissure (chronic).

Important outcomes Fissure healing, persistence, or recurrence, Symptom improvement
Studies (Participants) Outcome Comparison Type of evidence Quality Consistency Directness Effect size GRADE Comment
What are the effects of surgical treatments for chronic anal fissure?
1 (36) Fissure healing, persistence, or recurrence Anal stretch/dilation versus nitric oxide donors (topical glyceryl trinitrate) 4 –2 0 –1 0 Very low Quality points deducted for sparse data and unclear randomisation; directness point deducted for short follow-up
9 (694) Fissure healing, persistence, or recurrence Internal anal sphincterotomy versus nitric oxide donors (topical glyceryl trinitrate, topical isosorbide dinitrate) 4 –1 0 0 +2 High Quality point deducted for weak methods (unclear blinding); effect-size points added for OR >5
1 (80) Symptom improvement Internal anal sphincterotomy versus nitric oxide donors (topical glyceryl trinitrate, topical isosorbide dinitrate) 4 –2 0 0 0 Low Quality points deducted for sparse data and significant between-group differences at baseline
8 (535) Fissure healing, persistence, or recurrence Internal anal sphincterotomy versus botulinum A toxin-haemagglutinin complex 4 0 0 0 +2 High Effect-size points added for OR >5
2 (120) Symptom improvement Internal anal sphincterotomy versus botulinum A toxin-haemagglutinin complex 4 –3 0 0 0 Very low Quality points deducted for weak methods (unclear blinding), sparse data, and incomplete reporting of results
4 (468) Fissure healing, persistence, or recurrence Internal anal sphincterotomy versus calcium channel blockers 4 –2 –1 0 +2 Low Quality points deducted for weak methods, short follow up in 2 RCTs; consistency point deducted for heterogeneity; effect-size points added for OR >5
1 (80) Symptom improvement Internal anal sphincterotomy versus calcium channel blockers 4 –2 0 0 0 Low Quality points deducted for sparse data and significant between-group differences at baseline
9 (582) Fissure healing, persistence, or recurrence Internal anal sphincterotomy versus anal stretch/dilation 4 –1 –1 0 0 Low Quality point deducted for weak methods of some included RCTs; consistency point deducted for statistical heterogeneity
5 (336) Fissure healing, persistence, or recurrence Open versus closed internal anal sphincterotomy 4 –2 0 0 0 Low Quality points deducted for randomisation by pulling cards and unclear blinding
3 (228) Fissure healing, persistence, or recurrence Different lengths of internal anal sphincterotomy division versus each other 4 –3 0 –1 +2 Low Quality points deducted for quasi-randomisation in 1 RCT and unclear allocation concealment and blinding in all 3 RCTs; directness point deducted for small number of events (1 event in 1 arm); effect-size points added for OR <0.2
1 (40) Fissure healing, persistence, or recurrence Internal anal sphincterotomy versus anal advancement flap 4 –1 0 –1 0 Low Quality point deducted for sparse data; directness point deducted for small number of events (3 people in total not healed)
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We initially allocate 4 points to evidence from RCTs, and 2 points to evidence from observational studies. To attain the final GRADE score for a given comparison, points are deducted or added from this initial score based on preset criteria relating to the categories of quality, directness, consistency, and effect size. Quality: based on issues affecting methodological rigour (e.g., incomplete reporting of results, quasi-randomisation, sparse data [<200 people in the analysis]). Consistency: based on similarity of results across studies. Directness: based on generalisability of population or outcomes. Effect size: based on magnitude of effect as measured by statistics such as relative risk, odds ratio, or hazard ratio.

Glossary

Anal advancement flap

A procedure in which the edges of an anal fissure are excised and healthy anal skin is mobilised to cover the defect. This procedure is commonly used for anal ulcers: for example, in people who are HIV-positive.

Anal dilation/anal stretch

Stretching as opposed to cutting of the internal anal sphincter. Traditionally, this has been done by insertion of fingers into the anus, but more recently dilators have been used, which may be less traumatic.

Botulinum A toxin–haemagglutinin complex (botulinum A toxin-hc)

A formulation of botulinum A toxin and haemagglutinin for injection. Different preparations are used at different doses for the same indication, and the strength (in units) of one preparation may not be equivalent to that of another preparation labelled as containing the same number of units.

High-quality evidence

Further research is very unlikely to change our confidence in the estimate of effect.

Internal anal sphincterotomy

Incision in the internal anal sphincter, either posteriorly or laterally, but more commonly laterally, and usually "tailored" to the length of the fissure.

Low-quality evidence

Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.

Topical glyceryl trinitrate

A formulation usually of 0.2% to 0.4% ointment, applied lightly around the anal opening.

Very low-quality evidence

Any estimate of effect is very uncertain.

Disclaimer

The information contained in this publication is intended for medical professionals. Categories presented in Clinical Evidence indicate a judgement about the strength of the evidence available to our contributors prior to publication and the relevant importance of benefit and harms. We rely on our contributors to confirm the accuracy of the information presented and to adhere to describe accepted practices. Readers should be aware that professionals in the field may have different opinions. Because of this and regular advances in medical research we strongly recommend that readers' independently verify specified treatments and drugs including manufacturers' guidance. Also, the categories do not indicate whether a particular treatment is generally appropriate or whether it is suitable for a particular individual. Ultimately it is the readers' responsibility to make their own professional judgements, so to appropriately advise and treat their patients. To the fullest extent permitted by law, BMJ Publishing Group Limited and its editors are not responsible for any losses, injury or damage caused to any person or property (including under contract, by negligence, products liability or otherwise) whether they be direct or indirect, special, incidental or consequential, resulting from the application of the information in this publication.

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BMJ Clin Evid. 2014 Nov 12;2014:0407.

Anal advancement flap

Summary

We don’t know how effective anal advancement flap and internal anal sphincterotomy are, compared with each other, at increasing the proportion of people with healed anal fissures at 3 months.

Benefits and harms

Anal advancement flap versus internal anal sphincterotomy:

See option on Internal anal sphincterotomy.

Comment

Anal advancement flap is used to treat some atypical fissures such as those caused by herpes or HIV, wherein any degree of sphincterotomy is generally felt to be unwise. However, there are no RCTs comparing anal advancement flap with more conservative interventions in the setting of atypical chronic anal fissure.

Substantive changes

Anal advancement flap One systematic review updated. No new data added. Categorisation unchanged (unknown effectiveness).

BMJ Clin Evid. 2014 Nov 12;2014:0407.

Anal stretch/dilation

Summary

We don’t know whether anal dilation/anal stretch is more effective than topical glyceryl trinitrate at reducing the proportion of people with anal fissure. Topical glyceryl trinitrate increases the risk of headache.

Anal stretch may be less effective than internal anal sphincterotomy at reducing the proportion of people with anal fissure. However, the significance of the result depended on the analysis performed.

The risk of flatus incontinence may be greater with anal stretch than with internal anal sphincterotomy.

We don’t know whether pneumatic balloon dilation or controlled-intermittent anal dilation is more effective than internal anal sphincterotomy in reducing the proportion of people with anal fissure.

One small RCT found limited evidence that controlled-intermittent anal dilation may be equivalent to sphincterotomy in fissure healing, with negligible incontinence risk.

Benefits and harms

Anal stretch/dilation versus nitric oxide donors (topical glyceryl trinitrate):

We found one systematic review (search date 2010), which included one RCT that met our inclusion criteria.

Fissure healing, persistence, or recurrence

Anal stretch/dilation versus nitric oxide donors (topical glyceryl trinitrate) We don’t know whether anal dilation is more effective than topical glyceryl trinitrate at reducing the persistence of anal fissure because outcomes were not reported beyond 30 days in this small RCT (very low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Fissure healing, persistence, or recurrence

Systematic review		 36 people with chronic anal fissure
Data from 1 RCT		 Non-healing of anal fissure (persistence or recurrence)
1/18 (6%) with anal dilation
11/18 (61%) with topical glyceryl trinitrate
OR 0.04
95% CI 0.00 to 0.35
See Further information on studies 		Large effect size anal dilation
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Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

Systematic review		 36 people with chronic anal fissure
Data from 1 RCT		 Headache
0/18 (0%) with anal dilation
7/18 (39%) with topical glyceryl trinitrate
OR 24.13
95% CI 1.26 to 463.72
See Further information on studies 		Large effect size anal dilation
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Anal stretch/dilation versus anal sphincterotomy:

See option on Internal anal sphincterotomy

Further information on studies

A small RCT where the level of blinding was unclear, outcomes were not reported beyond 30 days, and method of randomisation and allocation concealment was unclear (randomisation by secretarial staff, further details not reported).

Comment

The key study, an RCT comparing the old digital stretch with balloon dilation, has not been conducted. Although there are no RCT data, there is a presumption that balloon dilation may be more effective because it gives rise to uniform application of pressure to the anal sphincter, and requires reduced anal opening. More importantly, balloon dilation has not been associated with incontinence.

Substantive changes

Anal stretch/dilation One systematic review updated. No new data added. Categorisation unchanged (unlikely to be beneficial).

BMJ Clin Evid. 2014 Nov 12;2014:0407.

Internal anal sphincterotomy

Summary

Internal anal sphincterotomy is more effective than medical therapy for chronic anal fissure in adults. It improves fissure healing compared with treatment with topical nitric oxide donors ( glyceryl trinitrate , isosorbide dinitrate), botulinum A toxin-haemagglutinin complex , and calcium channel blockers (nifedipine, diltiazem).

Internal anal sphincterotomy also increases fissure healing compared with anal stretch , and anal stretch is more likely to cause flatus incontinence. One small RCT found limited evidence that controlled anal dilation may be equivalent to sphincterotomy in fissure healing, with negligible incontinence risk.

The risk of minor flatus or faecal incontinence is greater with internal anal sphincterotomy than with botulinum toxin. Topical glyceryl trinitrate increases the risk of headache compared with internal anal sphincterotomy.

The risk of flatus incontinence may be greater with anal stretch than with internal anal sphincterotomy.

We don’t know whether internal anal sphincterotomy is better or worse than anal advancement flap in improving fissure healing.

Longer internal anal sphincter division (to the dentate line as opposed to the fissure apex only) may be more effective at reducing the proportion of people with anal fissure.

Open partial lateral internal anal sphincterotomy may be equivalent to closed partial internal anal sphincterotomy in fissure healing.

Benefits and harms

Internal anal sphincterotomy versus nitric oxide donors (topical glyceryl trinitrate, topical isosorbide dinitrate):

We found one systematic review (search date 2010), which included seven RCTs that met our inclusion criteria. We found one further RCT, and one subsequent RCT.

Fissure healing, persistence, or recurrence

Internal anal sphincterotomy compared with nitric oxide donors Internal anal sphincterotomy seems to be more effective than nitric oxide donors (glyceryl trinitrate or isosorbide mononitrate) at reducing the proportion of people with anal fissure at 6 weeks to 2 years (high-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Fissure healing, persistence, or recurrence

Systematic review		 407 people with chronic anal fissure
7 RCTs in this analysis		 Non-healing of anal fissure (persistence or recurrence) 4 weeks–2 years
25/204 (12%) with lateral internal sphincterotomy
92/203 (45%) with nitric oxide donors (topical glyceryl trinitrate, topical isosorbide dinitrate)
OR 7.49
95% CI 4.29 to 13.07
P <0.00001 		Large effect size lateral internal sphincterotomy

RCT
4-armed trial 		160 people with chronic anal fissure Recurrence up to 5 years
4/40 (10%) with open lateral internal sphincterotomy
23/40 (58%) with topical glyceryl trinitrate
Not reported

RCT		 207 people with chronic anal fissure Healing 1 year
98/102 (96%) with lateral internal sphincterotomy
76/105 (72%) with topical isosorbide dinitrate
P <0.001 		Effect size not calculated lateral internal sphincterotomy
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Symptom improvement

Internal anal sphincterotomy compared with nitric oxide donors Internal anal sphincterotomy may be more effective at reducing time to complete pain relief than nitric oxide donors (topical glyceryl trinitrate) (low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Symptom improvement

RCT
4-armed trial 		160 people with chronic anal fissure Mean time to complete pain relief (pain assessed daily using visual analogue scale)
5.7 days (40 people) with open lateral internal sphincterotomy
15.6 days (40 people) with topical glyceryl trinitrate
P <0.001 		Effect size not calculated lateral internal sphincterotomy
Open in a new tab

No data from the following reference on this outcome.

Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

Systematic review		 384 people with chronic anal fissure
7 RCTs in this analysis		 Minor flatus or faecal incontinence 4 weeks–2 years
15/191 (8%) with lateral internal sphincterotomy
7/193 (4%) with nitric oxide donors (topical glyceryl trinitrate, topical isosorbide dinitrate)
OR 0.51
95 % CI 0.22 to 1.16
P = 0.11 		Not significant

Systematic review		 381 people with chronic anal fissure Headache 4 weeks–2 years
2/191 (1%) with lateral internal sphincterotomy
66/190 (35%) with nitric oxide donors (topical glyceryl trinitrate, topical isosorbide dinitrate)
OR 29.06
95 % CI 10.30 to 82.04
P <0.00001 		Large effect size lateral internal sphincterotomy

RCT
4-armed trial 		160 people with chronic anal fissure Flatus incontinence
2/40 (5%) with open lateral internal sphincterotomy
0/40 (0%) with topical glyceryl trinitrate
Not reported

RCT
4-armed trial 		160 people with chronic anal fissure Headache
0/40 (0%) with open lateral internal sphincterotomy
6/40 (15%) with topical isosorbide dinitrate
Not reported

RCT		 207 people with chronic anal fissure Moderate anal incontinence
6/102 (6%) with lateral internal sphincterotomy
0/105 (0%) with topical isosorbide dinitrate ointment
Not reported

RCT		 207 people with chronic anal fissure Headache 1 year
0/102 (0%) with lateral internal sphincterotomy
7/105 (7%) with topical isosorbide dinitrate ointment
Not reported
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Internal anal sphincterotomy versus botulinum A toxin-haemagglutinin complex:

We found one systematic review (search date 2010), which included five RCTs that met our inclusion criteria. We found one further RCT, and two subsequent RCTs.

Fissure healing, persistence, or recurrence

Internal anal sphincterotomy compared with botulinum A toxin-haemagglutinin complex Internal anal sphincterotomy is more effective than botulinum A toxin-haemagglutinin at reducing non-healing of anal fissure at 18 weeks to 3 years (high-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Fissure healing, persistence, or recurrence

Systematic review		 365 people with chronic anal fissure
5 RCTs in this analysis		 Non-healing of anal fissure 18 weeks–3 years
19/177 (11%) with lateral internal sphincterotomy
77/188 (41%) with botulinum toxin
OR 7.20
95% CI 3.97 to 13.07
P <0.00001 		Large effect size lateral internal sphincterotomy

RCT
4-armed trial 		160 people with chronic anal fissure Recurrence up to 5 years
4/40 (10%) with open lateral internal sphincterotomy
21/40 (53%) with botulinum toxin
Not reported

RCT		 40 people with chronic anal fissure Persistence or recurrence 3 years
0/20 (0%) with lateral internal sphincterotomy
7/20 (35%) with botulinum toxin
P = 0.008 		Effect size not calculated lateral internal sphincterotomy

RCT		 50 people with chronic anal fissure Complete healing of fissure 12 months
23/25 (92%) with lateral internal sphincterotomy
12/25 (48%) with botulinum toxin
P = 0.001 		Effect size not calculated lateral internal sphincterotomy
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Symptom improvement

Internal anal sphincterotomy versus botulinum A toxin-haemagglutinin complex We don’t know how effective internal anal sphincterotomy and botulinum A toxin-haemagglutinin complex are, compared with each other, at reducing post-treatment pain (very low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Symptom improvement

RCT
4-armed trial 		160 people with chronic anal fissure Mean time to complete pain relief
5.7 days (40 people) with open lateral internal sphincterotomy
2.7 days (40 people) with botulinum toxin
Absolute results not reported
Reported as not significant
P value not reported 		Not significant

RCT		 40 people with chronic anal fissure Pain score day 7
with lateral internal sphincterotomy
with botulinum toxin
P = 0.041 		Effect size not calculated lateral internal sphincterotomy
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No data from the following reference on this outcome.

Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

Systematic review		 321 people with chronic anal fissure
4 RCTs in this analysis		 Minor flatus or faecal incontinence 18 weeks–3 years
14/155 (9%) with lateral internal sphincterotomy
0/166 (0%) with botulinum toxin
OR 0.11
95% CI 0.02 to 0.46
P = 0.0028 		Large effect size botulinum toxin

RCT
4-armed trial 		160 people with chronic anal fissure Flatus incontinence
2/40 (5%) with open lateral internal sphincterotomy
0/40 (0%) with botulinum toxin
Not reported

RCT		 40 people with chronic anal fissure Incontinence
4/20 (20%) with lateral internal sphincterotomy
3/20 (15%) with botulinum toxin
P = 1.000 		Not significant

RCT		 50 people with chronic anal fissure Incontinence 12 months
1/25 (4%) with lateral internal sphincterotomy
0/25 (0%) with botulinum toxin
P >0.05 		Not significant
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Internal anal sphincterotomy versus calcium channel blockers:

We found one systematic review (search date 2010), which included two RCTs that met our inclusion criteria. We found one further RCT, and one subsequent RCT.

Fissure healing, persistence, or recurrence

Internal anal sphincterotomy compared with calcium channel blockers Internal anal sphincterotomy may be more effective than calcium channel blockers (nifedipine, diltiazem) at reducing non-healing of anal fissure at 8 weeks to 4 months; however, we don’t know how they compare long term (low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Fissure healing, persistence, or recurrence

Systematic review		 200 people with chronic anal fissure
2 RCTs in this analysis		 Non-healing of anal fissure 8 weeks–4 months
4/124 (3%) with lateral internal sphincterotomy
40/76 (53%) with calcium channel blocker (oral or topical nifedipine)
OR 59.77
95% CI 15.47 to 230.96
P <0.00001
I2 = 64%, P = 0.09
See Further information on studies 		Large effect size lateral internal sphincterotomy

RCT
4-armed trial 		160 people with chronic anal fissure Recurrence up to 5 years
4/40 (10%) with open lateral internal sphincterotomy
26/40 (65%) with topical diltiazem
Not reported

RCT		 188 people with chronic anal fissure Recurrence 1 year
0/89 (0%) with lateral internal sphincterotomy
26/40 (65%) with topical diltiazem
Not reported
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Symptom improvement

Internal anal sphincterotomy compared with calcium channel blockers Internal anal sphincterotomy may be more effective at reducing time to complete pain relief than calcium channel blockers (topical diltiazem) (low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Symptom improvement

RCT
4-armed trial 		160 people with chronic anal fissure Mean time to complete pain relief
5.7 days (40 people) with open lateral internal sphincterotomy
15.7 days (40 people) with topical diltiazem
P <0.001 		Effect size not calculated open lateral internal sphincterotomy
Open in a new tab

No data from the following reference on this outcome.

Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

Systematic review		 64 people with chronic anal fissure
Data from 1 RCT		 Incontinence 8 weeks
4/32 (13%) with lateral internal sphincterotomy
0/32 (0%) with calcium channel blocker (topical nifedipine)
OR 0.10
95% CI 0.01 to 1.89
P = 0.12 		Not significant

Systematic review		 64 people with chronic anal fissure
Data from 1 RCT		 Headache 8 weeks
0/32 (0%) with lateral internal sphincterotomy
5/32 (16%) with calcium channel blocker (topical nifedipine)
OR 13.00
95% CI 0.69 to 245.72
P = 0.087 		Not significant

RCT
4-armed trial 		160 people with chronic anal fissure Flatus incontinence
2/40 (5%) with open lateral internal sphincterotomy
0/40 (0%) with topical diltiazem
Not reported

RCT
4-armed trial 		120 people with chronic anal fissure Headache
0/40 (0%) with open lateral internal sphincterotomy
2/40 (5%) with topical diltiazem
Not reported

RCT		 188 people with chronic anal fissure Headache 6 weeks
0/97 (0%) with lateral internal sphincterotomy
5/91 (5%) with topical diltiazem
P <0.0001 		Effect size not calculated lateral internal sphincterotomy

RCT		 188 people with chronic anal fissure Faecal incontinence 1 year
0/97 (0%) with lateral internal sphincterotomy
0/91 (0%) with topical diltiazem
No events, effect size not estimable
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Internal anal sphincterotomy versus anal stretch/dilation:

We found one systematic review (search date March 2011), which included nine RCTs (6 RCTs anal stretch, 385 people; 1 RCT anal dilation, 108 people, all manual; 1 RCT pneumatic balloon dilation, 49 people; 1 RCT controlled intermittent anal dilation, 40 people) that met our inclusion criteria.

Fissure healing, persistence, or recurrence

Internal anal sphincterotomy compared with anal stretch/dilation Internal anal sphincterotomy may be more effective than anal stretch at reducing the proportion of people with anal fissure. However,the significance of the result depended upon the analysis performed. We don’t know whether internal anal sphincterotomy is more effective than pneumatic balloon dilation or controlled-intermittent anal dilation at reducing the proportion of people with anal fissure (low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Fissure healing, persistence, or recurrence

Systematic review		 493 people with chronic anal fissure
7 RCTs in this analysis		 Persistence of anal fissure
18/229 (8%) with internal anal sphincterotomy
29/264 (11%) with anal stretch
OR 1.55
95% CI 0.85 to 2.86
P = 0.16
I2 = 58%, P = 0.03
See Further information on studies 		Not significant

Systematic review		 328 people with chronic anal fissure
5 RCTs in this analysis		 Persistence of anal fissure
6/164 (4%) with internal anal sphincterotomy
23/164 (14%) with anal stretch
OR 4.42
95% CI 1.75 to 11.18
P = 0.0017
See Further information on studies 		Moderate effect size internal anal sphincterotomy

Systematic review		 49 people with chronic anal fissure
Data from 1 RCT		 Treatment failure
3/25 (12%) with lateral internal sphincterotomy
4/24 (17%) with pneumatic balloon dilation
OR 1.47
95% CI 0.29 to 7.37
P = 0.64 		Not significant

Systematic review		 40 people with chronic anal fissure
Data from 1 RCT		 Treatment failure
3/20 (15%) with lateral internal sphincterotomy
2/20 (10%) with controlled-intermittent anal dilation
OR 0.63
95% CI 0.09 to 4.24
P = 0.63 		Not significant
Open in a new tab

Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

Systematic review		 493 people with chronic anal fissure
7 RCTs in this analysis		 Minor flatus incontinence
6/229 (3%) with internal anal sphincterotomy
32/264 (12%) with anal stretch
OR 4.03
95% CI 2.04 to 7.96
P = 0.000062 		Moderate effect size internal anal sphincterotomy

Systematic review		 49 people with chronic anal fissure
Data from 1 RCT		 Persistent anal incontinence
4/25 (16%) with lateral internal sphincterotomy
0/24 (0%) with pneumatic balloon dilation
OR 0.10
95% CI 0.00 to 1.92
P = 0.13 		Not significant

Systematic review		 40 people with chronic anal fissure
Data from 1 RCT		 Incontinence
0/20 (0%) with lateral internal sphincterotomy
0/20 (0%) with controlled-intermittent anal dilation
No events, effect size not estimable
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Open versus closed internal anal sphincterotomy:

We found one systematic review (search date 2011), which included five RCTs that met our inclusion criteria.

Fissure healing, persistence, or recurrence

Open compared with closed internal anal sphincterotomy We don’t know how effective open partial lateral internal anal sphincterotomy and closed partial lateral sphincterotomy are, compared with each other, at reducing the proportion of people with anal fissure (low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Fissure healing, persistence, or recurrence

Systematic review		 336 people with chronic anal fissure
5 RCTs in this analysis		 Persistence of anal fissure
10/168 (6%) with open lateral internal sphincterotomy
10/168 (6%) with closed partial lateral internal sphincterotomy
OR 1.00
95% CI 0.40 to 2.48
P = 1.00 		Not significant
Open in a new tab

Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

Systematic review		 336 people with chronic anal fissure
5 RCTs in this analysis		 Minor flatus incontinence
15/168 (9%) with open lateral internal sphincterotomy
17/168 (10%) with closed partial lateral internal sphincterotomy
OR 0.87
95% CI 0.41 to 1.83
P = 0.71 		Not significant
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Different lengths of internal anal sphincterotomy division versus each other:

We found one systematic review (search date 2011), which examined variation of sphincter division from the length of the fissure to the level of the dentate line. The review included three RCTs that met our inclusion criteria.

Fissure healing, persistence, or recurrence

Different lengths of internal anal sphincter division compared with each other Longer sphincterotomy (to the dentate line as opposed to the fissure apex only) may be more effective at reducing the proportion of people with anal fissure (low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Fissure healing, persistence, or recurrence

Systematic review		 228 people with chronic anal fissure
3 RCTs in this analysis		 Treatment failure
1/114 (1%) with dentate line
11/114 (10%) with fissure apex
OR 0.15
95% CI 0.03 to 0.69
P = 0.015 		Large effect size dentate line
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Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

Systematic review		 138 people with chronic anal fissure
3 RCTs in this analysis		 Mean anal incontinence score
with dentate line
with fissure apex
Absolute results not reported
Mean difference –0.10
95% CI –0.34 to +0.14
P = 0.42 		Not significant
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Internal anal sphincterotomy versus anal advancement flap:

We found one systematic review (search date 2011), which included one RCT that compared internal anal sphincterotomy with anal advancement flap. We have reported results directly from the RCT.

Fissure healing, persistence, or recurrence

Internal anal sphincterotomy compared with anal advancement flap We don’t know how effective internal anal sphincterotomy and anal advancement flap are, compared with each other, at increasing the proportion of people with healed anal fissures at 3 months (low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Fissure healing, persistence, or recurrence

RCT		 40 people with chronic anal fissure
In review 		Anal fissure healing 3 months
20/20 (100%) with internal anal sphincterotomy
17/20 (85%) with anal advancement flap
P = 0.12 		Not significant
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Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

RCT		 40 people with chronic anal fissure
In review 		Incontinence 3 months
0/20 (0%) with internal anal sphincterotomy
0/20 (0%) with anal advancement flap
Not reported
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Further information on studies

Internal anal sphincterotomy versus anal stretch/dilation There was significant heterogeneity among the RCTs that contributed to the persistence of anal fissure analysis (I2 = 58%, P = 0.03). Sensitivity analysis found that the heterogeneity disappeared (I2 = 0%, P = 0.71) when two of the lower quality RCTs were omitted from the analysis. In one RCT, anal dilation was performed using a pneumatic balloon rather than manually. The level of blinding was not clear; 4/49 (8%) people withdrew from the study. Another RCT reported controlled-intermittent anal dilation performed under general anaesthesia using a repeated dilation-relaxation sequence.Open versus closed internal anal sphincterotomy In two of the included RCTs, randomisation was by pulling classification cards once surgery had been determined to be necessary, and in most RCTs the level of blinding was unclear. Different lengths of internal anal sphincterotomy division versus each other One RCT (92 people) used an inadequate randomisation method (by hospital number), and the level of allocation concealment and blinding in all three RCTs was not clear.

Internal anal sphincterotomy compared with nitric oxide donors One of the references included in adverse effects (headache, 4 weeks–2 years) compared hydropneumatic anal dilation with topical glyceryl trinitrate.Internal anal sphincterotomy compared with botulinum A toxin-haemagglutinin complex One RCT reported that there were no significant differences between treatments in haemorrhage or haematoma (haemorrhage: 1/40 [3%] with sphincterotomy v 1/40 [3%] with botulinum A; P >0.05; haematoma: 1/40 [3%] with sphincterotomy v 1/40 [3%] with botulinum A; P value not reported). Another RCT reported that internal anal sphincterotomy significantly delayed return to daily activities compared with botulinum A toxin-haemagglutinin complex (14.8 days with sphincterotomy v 1.0 day with botulinum A toxin-haemagglutinin complex; P < 0.0001).Internal anal sphincterotomy compared with calcium channel blockers Substantial heterogeneity (I2 = 64%) was reported in the meta-analysis for non-healing of anal fissure (8 weeks–4 months). The review raised concerns about quality issues, with one RCT considered to be at high risk of bias due to lack of blinding, high reported cure rates (100% for surgery and >90% for topical nifedipine), with a follow-up period of only 8 weeks. There were substantial problems with compliance in the nifedipine group (17 of 41 patients, 41% dropout rate) of the other RCT related to side-effects, continued anal pain, and slow healing. Also, one RCT reported that more people had adverse effects with nifedipine than with lateral anal sphincterotomy (16/32 [50%] v 6/32 [19%]; significance not reported). Flushing was reported in 5/32 (16%) patients taking nifedipine compared with 0/32 (0%) who underwent surgery. Rates of anal irritation were as follows: 6/32 (19%) with nifedipine versus 2/32 (6%) with lateral internal sphincterotomy.

Internal anal sphincterotomy compared with nitric oxide donors Mean squeeze anal pressure differed significantly between treatment groups at baseline (P <0.001). Patients randomised to open lateral internal sphincterotomy had a mean time to healing of 4.5 weeks compared with 5 weeks for glyceryl trinitrate ointment. Time to healing did not differ significantly between the four treatment groups in the study (P = 0.067). The authors report that both individuals who experienced flatus incontinence became completely continent within 12 weeks. Internal anal sphincterotomy compared with botulinum A toxin-haemagglutinin complex Mean squeeze anal pressure differed significantly between treatment groups at baseline (P <0.001). Patients randomised to open lateral internal sphincterotomy had a mean time to healing of 4.5 weeks compared with 5.1 weeks for botulinum toxin. Time to healing did not differ significantly between the four treatment groups in the study (P = 0.067). The authors report that both individuals who experienced flatus incontinence became completely continent within 12 weeks. Internal anal sphincterotomy compared with calcium channel blockers Mean squeeze anal pressure differed significantly between treatment groups at baseline (P <0.001). Patients randomised to open lateral internal sphincterotomy had a mean time to healing of 4.5 weeks compared with 5.1 weeks with 2% diltiazem ointment. Time to healing did not differ significantly between the four treatment groups in the study (P = 0.067). The authors report that both individuals who experienced flatus incontinence became completely continent within 12 weeks.

The isosorbide dinitrate content of the ointment could be increased from 0.25% to 0.5% if anal fissure had not healed at 4 weeks. Lateral internal sphincterotomy significantly increased the proportion of patients who experienced healing of anal fissure at 4 weeks, 8 weeks, and 6 months compared with isosorbide dinitrate ointment 0.25% (P <0.001). The proportion of patients with recurring anal fissure did not differ significantly between treatment groups at 1 year (1/102 [1%] with lateral internal sphincterotomy v 5/105 [5%] with isosorbide dinitrate ointment; P = 0.105). The authors state that all patients who experienced anal incontinence had improved incontinence symptom scores at 6 months.

Patients randomised to lateral internal sphincterotomy were more likely to experience complete healing of fissure at 12 weeks than those randomised to treatment with botulinum toxin (20/20 [100%] v 15/20 [75%]; P=0.047). Persistence or recurrence was less likely among surgical patients at both 1-year and 2-year follow-up than patients treated with botulinum toxin (P = 0.047 and P = 0.008, respectively). Incontinence was described as transient.

At 6 months, persistence or recurrence of fissure was more common among patients treated with botulinum toxin than those who underwent lateral internal sphincterotomy (11/25 [44%] v 3/25 [12%]; P = 0.005). Surgical patients were more likely to experience complete healing of fissure at 2 months (P = 0.001) and at 6 months (P = 0.005), but not at 3 months (P >0.05). Patients who underwent sphincterotomy were more likely to experience anal incontinence at 2 months (P = 0.005), 3 months (P <0.05) and 6 months (P <0.05).

This study reported complete fissure healing rates at 6 weeks of 96% (93/97) with sphincterotomy and 69% (63/91) with topical diltiazem.

This small trial found no significant difference in patient satisfaction at 3 months (people reporting themselves 'dissatisfied': 3/20 [15%] with internal anal sphincterotomy v 3/20 [15%] with anal advancement flap; people 'satisfied' or reporting the result as 'excellent': 17/20 [85%] with internal anal sphincterotomy v 17/20 [85%] with anal advancement flap; P value not reported).

Comment

Two major outcomes were considered by the review: persistence of the fissure and flatus/faecal incontinence. Post-surgical faecal incontinence may, however, be confused with post-surgical leakage (a short-term adverse effect) and requires substantial follow-up (at least 12 months) to be confirmed. Other outcomes (e.g., complications related to wound healing) are likely to be relevant. The two RCTs removed in the sensitivity analysis of internal anal sphincterotomy compared with anal stretch/dilation had a greater loss to follow-up than the other studies, and length of follow-up varied widely between participants. In one RCT, general anaesthesia was used in the anal stretch/dilation group, whereas internal anal sphincterotomy was performed under local anaesthetic. More evidence is needed to establish effects on fissure healing of anal advancement flap compared with internal anal sphincterotomy. Partial lateral sphincterotomy, open or closed, provides the most reliable long-term cure of anal fissure: it is more effective than any alternative drug treatment. The fear of incontinence has been the cause of increasing use of drug treatment. However, we found no publications on the treatment of internal sphincterotomy-related incontinence, or any publications describing such people seeking treatment. Studies included in the review suggest that sphincterotomy and controlled balloon dilation to at least 30 mm can cure fissure without incontinence risk. Quality-of-life studies suggest a high level of patient satisfaction with sphincterotomy. Sphincterotomy may be offered as a first-line treatment for chronic anal fissure, with the assurance of a 90% chance of permanent cure, or it may be offered as a back-up treatment for those who fail drug treatment.

Substantive changes

Internal anal sphincterotomy One systematic review updated (search date 2010), and five subsequent RCTs added. Categorisation unchanged (beneficial).

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