Internal sphincter
Involuntary smooth muscle that provides resting closure. Persistent spasm contributes to chronic fissure pain.
04 · Areas of surgical care
Proctology,
made clear.
Three conditions. Three different problems.
Piles are swollen vascular cushions. A fissure is a tear. A fistula is a tunnel after infection.
Symptoms overlap; an accurate examination prevents the wrong treatment. This guide is educational and does not diagnose an individual condition.
Guideline-informed patient education
Anatomy first. Treatment matched to severity.
Clinical pathways on this page are informed by current American Society of Colon and Rectal Surgeons guidance and patient resources—not by a device or procedure trend. ASCRS is referenced as an independent educational source; it does not endorse this website.
The anatomy
A valve, a sling and a sensitive lining.
The rectum stores stool. The internal and external sphincters close the anal canal. Puborectalis forms a muscular sling at the anorectal junction, while vascular cushions help create a fine seal.
Normal anorectal and pelvic-floor anatomyINVINCIS annotated atlas · coronal section
External sphincter
Voluntary skeletal muscle. Its relationship to a fistula determines how safely a tract can be laid open.
Puborectalis
A U-shaped part of the levator ani that pulls the anorectal junction forward for continence and releases during evacuation.
Dentate line
A sensory and anatomical boundary. Problems below it are usually more pain-sensitive than internal haemorrhoids above it.
The deeper support bowl
Levator ani includes puborectalis, pubococcygeus and iliococcygeus. Together with coccygeus, these muscles support the pelvic organs and coordinate continence, emptying and pressure.
The outlet and its anchor
The external anal sphincter encircles the anal canal. The perineal body and transverse perineal muscles help stabilise the outlet and connect nearby pelvic-floor structures.
Strength alone is not the answer
A pelvic floor must close when continence is needed and release when stool passes. Over-tight or poorly coordinated muscles can obstruct evacuation even when they are not “weak”.
Do not confuse the names
What each condition actually is.
Enlarged or displaced cushions
Normal vascular cushions become symptomatic when they enlarge, bleed, prolapse or thrombose. Internal piles often cause painless bright-red bleeding or prolapse; a thrombosed external pile can be very painful.
A linear tear
Passing hard stool—or sometimes frequent diarrhoea—tears the anal lining. Pain during and after stool, often with a small streak of bright blood, is typical.
An abnormal tunnel
An infected anal gland creates an abscess. After it drains, a persistent channel may connect the internal gland opening to skin near the anus, producing discharge, swelling or recurrent abscess.
Piles / haemorrhoids
Grade describes prolapse—not how much it hurts.
Internal haemorrhoids are graded by whether they come out of the anal canal and how they return. External disease, skin tags and thrombosis are described separately.
Internal haemorrhoidal prolapseGrade I–IV · matched coronal atlas sections
Grade IEnlarged cushions remain inside the canalGrade IIProlapse on straining and reduce spontaneouslyGrade IIIProlapse and require manual reductionGrade IVPersistently prolapsed and non-reducible
Correct the pressure cycle
Fibre, sufficient fluid, softer stool, activity, responding to the urge, avoiding prolonged sitting on the toilet and reducing repeated straining.
Office procedures
Rubber-band ligation is often the most effective office treatment. Injection sclerotherapy and infrared coagulation are alternatives for selected internal disease.
Operative treatment
Excisional haemorrhoidectomy is considered for substantial external or combined disease and failed office treatment. Doppler-guided artery ligation is an option in selected internal prolapse, with a pain–recurrence trade-off. Stapled haemorrhoidopexy is not routinely a first-line operation and does not treat external disease.
Timing matters
Analgesia and local measures are often reasonable. Selected patients with a recent, very painful thrombosed external haemorrhoid may benefit from early excision.
“Laser piles treatment” is not one universal operation.
A procedure name should follow the diagnosis, internal/external component, prolapse grade, previous treatment and the patient’s priorities—not lead them.
Anal fissure
Break the pain–spasm–poor healing cycle.
An acute fissure is usually present for less than six weeks. Chronicity is suggested by a visible internal-sphincter fibre, sentinel tag or hypertrophied anal papilla—not pain alone.
Chronic posterior anal fissureOblique sagittal cutaway + anal-verge clock face
Acute fissure
Soft, formed stool, fibre, fluid, warm sitz baths and appropriate pain relief often allow healing.
Persistent / chronic
Prescribed topical calcium-channel blocker or nitrate relaxes the internal sphincter. Botulinum toxin is another option.
Refractory fissure
Selected patients may benefit from lateral internal sphincterotomy, which heals well but requires careful continence-risk assessment. Advancement flap is a sphincter-preserving option in selected higher-risk patients.
Abscess & fistula-in-ano
Map the tunnel before choosing the operation.
The visible skin opening is only one end of the problem. The key question is how the tract passes around or through the sphincter complex.
Anal gland blocks
A tiny gland near the dentate line becomes infected.
Abscess develops
Pus tracks into the perianal, intersphincteric, ischioanal or deeper space.
It drains
The abscess opens itself or is surgically drained. Acute pain may improve.
A tract persists
An epithelialised tunnel can remain, causing recurrent swelling or discharge.
How a cryptoglandular anal fistula formsMagnified transsphincteric example
Parks classification of fistula-in-anoDefined by the tract's relationship to the sphincter complex
Type IIntersphinctericRuns in the plane between internal and external sphinctersType IITranssphinctericCrosses the external sphincter into ischioanal fatType IIISuprasphinctericAscends above puborectalis before descending to skinType IVExtrasphinctericEnters the rectum above the sphincter complex
Fistulotomy
Laying open a low tract can be highly effective when little sphincter is involved and continence is normal.
Drain first
An abscess usually needs prompt drainage. A loose draining seton may control infection and keep a complex tract open while definitive planning continues.
Preserve sphincter
Options include staged seton management, LIFT or an endorectal advancement flap. Recurrence and continence trade-offs differ; no one technique fits every tract.
Team-based care
MRI or endoanal ultrasound may map extensions. Crohn’s-related fistula often needs coordinated medical therapy plus surgical drainage or repair.
Constipation is more than frequency
Difficulty emptying matters—even if you go every day.
Constipation may reflect slow movement through the colon, hard stool, pelvic-floor outlet dysfunction or an overlap. Frequency alone can miss the problem.
Incomplete evacuation
You finish, yet still feel that stool remains in the rectum.
Digital assistance
Using a finger to remove stool, or pressing around the vagina or perineum to help it pass.
Hard, pellet-like stool
Dry, stony or lumpy stool that is difficult or painful to pass.
Straining or delay
Repeated pushing, long toilet visits or needing several attempts for one bowel movement.
Blood with stool
Bright-red blood can accompany piles or a fissure—but bleeding must not be assumed to be benign.
Pain & irritation
Burning, tearing pain, itching, swelling, discharge or soreness around the anus.
A practical pathway
Find out whether stool, transit or the outlet is the main barrier.
- Start with history and examination. Review medicines, diet, stool form, frequency, straining, digital assistance, bleeding and pelvic-floor function.
- Build a reliable stool routine. Fibre and fluid when suitable, activity, regular timing, and an osmotic laxative such as polyethylene glycol when advised.
- Test an outlet problem when needed. Balloon-expulsion testing, anorectal physiology and defecography can identify dyssynergia or structural obstruction.
- Retrain coordination. Pelvic-floor biofeedback is first-line treatment for dyssynergic defecation; surgery is reserved for carefully selected structural or refractory disease.
Pelvic floor & posture
Puborectalis is a sling—not a simple “sphincter”.
At rest it maintains a bend between rectum and anal canal for continence. During defecation, the puborectalis and external sphincter should relax as the anorectal angle opens.
Puborectalis and the anorectal angleMatched sagittal sections · pubic origin to posterior sling
Conventional sittingPuborectalis retains more sling tension and the anorectal junction remains more angulated.Supported squatCoordinated relaxation and pelvic-floor descent produce a straighter evacuation pathway.
Raise the knees
Use a stable footstool so knees sit above hips; keep feet supported rather than on tiptoe.
Lean and breathe
Lean slightly forward, rest forearms on thighs and let the abdomen expand. Avoid breath-holding and repeated forceful pushing.
Respect the urge
Allow unhurried privacy, but do not sit scrolling or strain for long periods. If nothing happens, pause and try later.
Do not force a squat
Balance, hip, knee or postoperative limitations may make full squatting unsuitable. A supported position is safer.
When “pushing harder” makes the outlet tighter
In dyssynergic defecation, puborectalis or the external sphincter fails to relax—or contracts paradoxically. This can cause incomplete evacuation, repeated straining and digital assistance. Pelvic-floor biofeedback retrains coordination; more laxative alone may not fix the outlet.
WARNING SIGNS
When not to wait.
Seek urgent medical assessment for:
- Heavy or continuous bleeding, clots, dizziness, faintness or weakness
- Severe or escalating anal pain, rapidly increasing swelling, fever or chills
- Pus with systemic illness, difficulty passing urine, confusion or feeling very unwell
- Black, tarry stool or dark maroon blood rather than a small bright-red streak
- Bleeding with unexplained weight loss, anaemia, abdominal pain or a persistent change in bowel habit
- Abdominal swelling and vomiting with inability to pass stool or gas
The consultation
Discreet care. Precise diagnosis. Sphincter-aware planning.
An assessment may include symptom history, abdominal and anorectal examination, anoscopy or proctoscopy, and selected colonoscopy, MRI, ultrasound or pelvic-floor tests. You should understand what the diagnosis is, what can improve without an operation and why a particular procedure fits the anatomy.
Request a proctology consultationCommon questions
Answers without embarrassment.
Are piles the same as fissure or fistula?
No. Piles are enlarged or displaced vascular cushions. A fissure is a linear tear in the anal lining. A fistula is an abnormal tunnel, usually left behind after an infected anal gland or abscess. They can produce overlapping symptoms but need different treatment.
Does rectal bleeding always mean piles?
No. Piles and fissures are common causes, but polyps, inflammation, diverticular disease and colorectal cancer can also bleed. New, persistent, unexplained or heavy bleeding—especially with weight loss, anaemia, abdominal symptoms or altered bowel habit—needs proper assessment.
Can piles improve without an operation?
Often, yes. Fibre, adequate fluid, softer stool, less straining and shorter toilet time are first-line measures. Persistent grade I–II and selected grade III internal piles may respond to office procedures. Larger external or combined grade III–IV disease may need surgery.
Can an anal fissure heal with medicines?
Many acute fissures heal when stool is softened and local trauma stops. Chronic fissures may need a prescribed ointment that relaxes the internal sphincter, botulinum toxin or an operation. The choice considers duration, sphincter tone and continence risk.
Will antibiotics cure a fistula?
Antibiotics can be important for selected infection or systemic illness, but they do not usually remove an established epithelialised tract. An abscess generally needs drainage; definitive fistula treatment is planned around anatomy and sphincter preservation.
Is laser the best treatment for every pile or fistula?
No. Laser is a tool, not a diagnosis or a guarantee. Grade, tract anatomy, branches, previous surgery, continence, Crohn’s disease and the quality of evidence matter more than the device name.
Can fistula surgery affect continence?
Any procedure that divides sphincter muscle can affect continence. A low simple tract may be suitable for fistulotomy; higher or complex tracts often need sphincter-preserving or staged procedures. The map of the tract and baseline continence should guide the plan.
Is a full squat compulsory for a good bowel movement?
No. Squatting generally creates a more open anorectal pathway, but it is not safe or practical for everyone. Sitting with feet supported on a stable stool, knees above hips, leaning forward and relaxing the abdomen can approximate the mechanics without forcing a deep squat.
When is a colonoscopy considered?
It may be advised when there is no clear anorectal source for bleeding, symptoms continue after treatment, there is abdominal pain or new/progressive constipation, alarm features are present, or colorectal-cancer screening is due. The decision is individual.
Medical references
Treatment pathways reference the American Society of Colon and Rectal Surgeons clinical guidelines for haemorrhoids, anal fissure, anorectal abscess and fistula, and chronic constipation. Anatomical landmarks reference the NCBI reviews of the anal canal and levator ani; pelvic-floor physiology references the NCBI review of pelvic-floor and defecography anatomy. Patient context also references ASCRS patient information and the NIDDK constipation guide.
Reviewed for website publication in August 2026. Illustrations are original patient-education diagrams informed by standard anorectal anatomy; they are not surgical maps or a substitute for examination.