Editing Incontinence

Involuntary leakage of faecal material in anyone over four years old.

== '''Terminology''' ==

* Anal incontinence     incorporates loss of flatus, faecal incontinence does not
* '''Urge     incontinence'''     (aware, running to bathroom but don't make it - suggests external     sphincter problem) vs '''passive incontinence''' (unaware of occurrence -     suggests more a problem with internal sphincter)

== '''Factors contributing to normal continence''' ==

=== '''Mechanical/anatomical     factors''' ===

** Anal sphincter
*** Internal - 70% of resting       sphincter pressure, but only 40% after distension of the rectum
*** External - contributes via       voluntary control
** Anal vascular cushions -      10-20% of resting tone
** Puborectalis      muscle/anorectal angle which acts like a flap valve

=== '''Rectal/anal     sensation''' ===

** Pudendal nerve (S2, 3, 4)      innervates EAS
** Pelvic branches (S3 and 4)      innervate puborectalis
** Rectal distension is      transmitted along S2, 3, 4 PNS nerves
** Recto-anal inhibitory reflex      - when distended with stool, the internal sphincter relaxes, followed by      reflexive contraction of EAS, creating a sensation of urgency. This is      followed by pelvic floor relaxing, decreasing acuity of ano-rectal angle,      and defecation (if appropriate). Voluntary contraction of the pelvic      floor and EAS causes the sensation of urgency to subside as the rectum      accommodates.
** Anal sampling - as the IAS      relaxes, a small amount of stool can be 'sampled' and moved down to anus,      allowing for differentiation of gas and solid stool.

=== '''Rectal     compliance''' ===

** Storage of stool to defer      defecation

=== '''Stool     consistency''' ===

** Especially important in      patients with other functional problems

== '''Aetiology''' ==

=== '''Structural     problems''' ===

** Anal sphincter disruption
*** Obstetric (most common) - ''trial       non-operative options, then surgically repair or SNS''
**** Prolonged second stage        (pudendal nerve injury)
**** Actual passage of baby
**** Instruments
**** Often doesn't become        symptomatic until post-menopause
*** Iatrogenic ''- fix       underlying cause, then optimise medical management, consider SNS''
**** LIS
**** Fistulotomy
**** Haemorrhoidectomy
**** Radiation
*** Anorectal disease ''- fix       underlying cause - surgically''
**** Rectal prolapse
***** Lead-point of prolapse         acts like an intussusception, causing stretch of anal canal, and         subsequent damage
**** Prolapsing internal        haemorrhoids
** Disruption of pelvic floor -      ''surgically      repair or SNS''
*** Associated with ageing -       diminished muscle bulk and strength
*** Excessive perineal descent       - associated with denervation of the pelvic floor
*** Traumatic
**** Perineal impalement
**** Voluntary anoreceptive        intercourse
**** Foreign bodies
**** Sexual abuse

=== '''Functional     problems''' - ''bowel     regime to prevent constipation'' ===

** Neurologic - loss of stool      awareness and sensation, often leading to mega-rectum with overflow      incontinence (requires faecal impaction)
*** Obstetric (pudendal nerve       injury)
*** MS
*** CNS disease - spinal cord       injury or tumour
*** Diabetes
*** CVA
** Reduced rectal compliance - ''treat      underlying cause''
*** IBD
*** Radiation proctitis
*** Distal rectal cancer
*** Rectal surgery including       pouches

=== '''Changes in     stool characteristics''' - ''treat underlying cause'' ===

** Severe diarrhoea

=== '''Others''' - ''manage     symptoms and in some cases stoma'' ===

** Physical mobility
** Dementia
** Intellectual disability

== '''History''' ==

* Differentiate true     incontinence from urgency/frequency
* Solids/liquids/gas
* Onset
* Duration
* Frequency
* Amount
* Type
* Nocturnal episodes
* Precipitating events
* Awareness of incontinence
* Consider neurologic cause     (lower back/perianal pain, motor or sensory symptoms in extremities,     urinary incontinence)
* Prior anorectal surgery,     pelvic irradiation, diabetes, neurologic disease
* Obstetric history (number of     vaginal deliveries, prolonged labour, use of forceps, lacerations)
* Ask if tissue ever protrudes
* St Mark's incontinence score

== '''Exam''' ==

* Inspection (chemical     dermatitis, fistula, prolapsing haemorrhoids, rectal prolapse)
* Perianal sensation (absence     of anal wink reflex suggests nerve damage)
* DRE (mass, assess resting     anal tone and strength of squeeze, rectocoele, rectal prolapse, rectal     mass, stricture, fistula)
* Anoscopy or proctoscopy -     look for proctitis/cancer

== '''Investigations''' ==

* Stool studies in patients     with diarrhoea
* Endoscopy
** Flex sig in patients      <40yo with no increased risk of CRC
** Colonoscopy otherwise
* Endorectal US (if fail to     respond to initial management)
** Looking for sphincter      defects
* Defecography (defecating     proctogram, or defecating MRI proctogram)
** Looking for rectocoele or      other pelvic floor defects
** Partial evacuation of      contents
** Order if there are features      of obstructed defecation
* Anorectal manometry (if fail     to respond to initial management)
** Looking for sphincter      defects
** Both with and without anal      squeeze
* Balloon expulsion test
* Electromyography
* Pudendal nerve terminal motor     latency
** Controversial

== '''Initial management''' ==

=== Supportive care ===

** Wait 9-12 months after      childbirth to investigate
** Avoid food or activities      known to worsen symptoms
*** Avoid incompletely digested       sugars (fructose, lactose) and caffeine
** Keep a food or symptom diary
** Improve perianal skin      hygiene
*** Keep clean and dry, without       excessive wiping
*** Can use wet wipes
*** Barrier cream eg zinc oxide       to perianal skin
*** Incontinence pads

=== Medical therapy - aimed at     reducing stool frequency or improving stool consistency ===

** Bulking agents, esp in      patients with low-volume, loose stools
*** Fibre - psillium husk
** Anti-diarrhoeal agents - can      trial loperamide
*** Be aware this can       exacerbate things in patients with decreased rectal compliance       (radiation proctitis, rectal stricture)
*** If no response to       loperamide, bismuth subsalicylate or cholestyramine may provide benefit,       especially in patients post-cholecystectomy or post-ileal resection
** If faecal impaction, should      be disimpacted
** Evacuation of rectum with      suppositories or enemas
*** Esp useful for patients       with neurogenic bowel dysfunction - reduces rectal load

== '''Subsequent management''' ==

* Additional evaluation with     some combination of anorectal manometry and USS and defecography
* Biofeedback therapy - refer     to pelvic floor physiotherapist
** Particularly useful in      patients with intact anal sphincters and urge incontinence or decreased      rectal sensation; not useful with isolated internal anal sphincter      injury; not useful with neuro-psychiatric conditions; not useful with      impaired distension
** Rectal sensory retraining,      sphincter exercises, learning to co-ordinate voluntary external sphincter      contraction with the onset of rectal distension
** Non-invasive
** Time-consuming, but 64-89%      see an improvement, especially if there is some degree of preserved      voluntary sphincter contraction
** Low-risk - worth a try

== '''Surgical options:''' ==

* Reserved for patients in whom     conservative management has failed
** Not for those with overflow      incontinence
* Injectable bulking agents     (PTQ)
** Enhanced mechanical barrier      to faecal loss
** Injected into submucosa,      just above dentate line, four areas evenly spaced around anal canal
** Evidence supports slight      benefit but limited role now
* '''Sacral nerve     stimulation'''
** Stimulate S3 nerve root by      delivering mild electrical pulses
** Tined lead is placed next to      root under fluoro
** Mechanism of action not      entirely clear, but seems to reduce reported episodes of incontinence and      decreased urgency. Possibly enhances the ability of rectum to sense      distension.
** Most patients see an      improvement, and about half of patients achieve full continence
* Overlapping anterior     sphincteroplasty
** Best use is probably for      young patients who don't want to have an SNS for life
** Appropriate for patients      with a localised 90 to 180 degree full-thickness defect
** Should not be done for at      least 3-6 months after obstetric injury
** Function is often initially      good but deteriorates with time
** Direct repair of anal      sphincter - usually repair both sphincters as one muscle
** Technique
*** Perform under GA with bowel       prep. Consider diversion for difficult cases.
*** Hemicircumferential       incision around anus
*** Dissect out into       ischiorectal fat to expose the anus
**** Mobilise the anus from the        vagina if needed
*** Split the muscle scar down       its length and develop the plane between the anal mucosa and the muscle       on either side
*** Reapproximate sphincter       edges with 2-0 PDS horizontal mattress suture - like repairing a tendon.       Aim for overlap of about 2cm.
* Repair of pelvic floor injury
** Indications
*** Rectal prolapse
*** Other pelvic floor injury
* Stoma creation
** Indications: failure of      medical therapy and other invasive therapies, patient preference
** Mostly sigmoid colostomy,      although in slow transit constipation, an ileostomy can be necessary


[[Category:Colorectal]]