Pathology -- Defecatory Disorders Flashcards

1
Q

2 defecatory disorders

A

Constipation

Fecal incontinence

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2
Q

9 causal conditions of constipation

A
  • Diet, lifestyle
  • Irritable bowel syndrome
  • Drugs
  • Neurogenic (central or peripheral)
  • Myopathic
  • Metbaolic
  • Pregnancy
  • Obstructive lesions
  • Anorectal disease
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3
Q

Define fecal incontinence

A
  • Varies from inadvertent soiling with liquid stool to the involuntary excretion of feces
  • Insufficient voluntary control of gas or stool
  • NOT a diagnosis, but a symptom
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4
Q

4 causal conditions of fecal incontinence

A
  • Pelvic floor intact
    • Neurological conditions
    • Overflow (i.e. impaction)
  • Pelvic floor affected
    • Acquired (i.e. traumatic birth)
    • Congenital
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5
Q

4 consequences of being unable to poop normally

A
  • Social isolation and stigmatization
  • Physical disability
  • Psychological distress
  • Societal costs – direct care, institutionalization, loss of productivity
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6
Q

Right colon and transverse colon functions

A

Churning and mixing

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7
Q

Left colon function

A

Water absorption and stool delivery

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8
Q

Rectum function

A

Stool storage until socially appropriate moment, termed capacitance

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9
Q

Norma capacitance of stool in rectum

A

200 - 250 mL

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10
Q

Anus function

A
  • Muscular cork to prevent involuntary stool loss
  • Allows us to distinguish between solid and liquid stool ,flatus
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11
Q

Dscribe the internal anal sphincter’s characteristics

A

Continuous with inner circular muscle

  • Smooth muscle
  • Involuntary control
  • Resting tone
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12
Q

Describe the external anal sphincter’s characteristics

A

Continuous with pelvic floor

  • Skeletal muscle
  • Voluntary control
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13
Q

4 layers of the anus

A
  • Internal anal sphincter
  • External anal sphincter
  • Longitudinal muscle
  • Anoderm
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14
Q

Define the dentate line

A

Endodern (hindgut) and ectoderm junction

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15
Q

Define the anal transition zone

A

Location of transition from endoderm to ectoderm, so has transitional epithelium (cloacogenic)

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16
Q

2 characteristics of the anoderm

A
  • Sensate (vs. insensate rectum)
  • Non-keratinized squamous epithelium
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17
Q

Parasympathetic pathway functions in GIT

A
  • Generally promotes GIT motility
  • Role in continence/rectal capacitance
  • Pelvic function
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18
Q

Efferent position of parasympathetic nerves for colon

A

Cranio-caudal

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19
Q

Sympathetic pathway functions in colon

A
  • Slows colonic motility
  • Fight or flight system
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20
Q

Effect position of sympathetic pathways to colon

A

Thoraco-lumbar

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21
Q

3 types of contractions in colon

A
  • High amplitude propagated contractions (HAC)
  • Low amplitude propagated contractions (LAC)
  • Segmental contractions
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22
Q

Characteristics of HAC

A
  • Transport stool over long distances (5 - 6 x/day)
  • Occur with waking and after meals
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23
Q

Characteristics of LAC

A
  • Related to meals/sleep-wake cycle (not clearly understood)
  • Propagate stool short distances, but more frequently (not clearly understood)
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24
Q

When is transit in the colon decreased?

A

LAC > HAC

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25
Q

When is transit in the colon normal

A

LAC = HAC

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26
Q

When is transit in the colon increased?

A

HAC > LAC

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27
Q

4 anatomic factors to maintain continence in order of importance

A
  • Internal anal sphincter resting tone (45%)
  • External sphincter (30%)
  • Hemorrhoidal plexus (10 - 15%)
  • Aorectal angle/puborectalis/flap-valve
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28
Q

4 important reflex arcs relating to the colon and rectum

A
  • Gastro-colic
  • Recto-anal inhibitory reflex (RAIR)
  • Recto-anal excitatory reflex (RAER)
  • Bulbocavernosus reflex
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29
Q

Trigger and effect of gastro-colic reflex

A

Food in mouth –> colonic motility, segmental contractions

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30
Q

Trigger and effect of recto-anal inhibitory reflex (RAIR)

A

Rectal distension –> RELAXATION of INTERnAL anal sphincter

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31
Q

Trigger and effect of recto-anal excitatory reflex (RAER)

A

Rectal distension –> CONTRACTION of EXTERNAL anal sphincter

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32
Q

Lowest spinal reflex and the efferent position

A

Bulbocavernosus reflex from S2,3,4

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33
Q

Location of CNS awareness of stool moving into rectum

A

Anterior cingulate and frontal gyri

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34
Q

What receptors does rectal distension stimulate?

A

Pressure receptors in rectum and pelvic side wall

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35
Q

Purpose of RAIR in normal defecation

A

“Sampling” of contents (air? solid?)

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36
Q

Purpose of RAER in normal defecation

A

Prevent involuntary loss

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37
Q

If defecation is not appropriate at the time that stool enters the rectum, what is the body’s response?

A
  • Voluntary contraction of EAS
  • Rectal accomodation (capacitance and compliance)
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38
Q

4 events if the decision to defecate is made

A
  • Valsalva maneauver (increase abdominal pressure, glottic closure)
  • Puborectal muscle RELAXATION
  • EAS relaxation
  • Emptying of rectal contents
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39
Q

Effect of puborectal muscle relaxation

A

Opens up anorectal angle and causes pelvic floor descent

40
Q

5 pro-defecatory stimuli

A
  • Exercise
  • Distension (bulky stools, fiber)
  • Waking up
  • Eating
  • Drugs (laxatives)
41
Q

Why is exercise a pro-defecatory stimulus?

A

Stimulates HAC

42
Q

Rome II criteria for adult constipation

A

Two or more of the following for at least 12 weeks (no necessarily consecutively) in the preceding 12 months:

  • Straining during >25% of bowel movements
  • Lumpy or hard stools for >25% of bowel movements
  • Sensation of incomplete evacuation for >25% of bowel movements
  • Sensation of anorectal blockage for >25% of bowel movements
  • Manual maneuvers to facilitate >25% of bowel movements (i.e. digital evacuation or support of the pelvic floor)
  • <3 bowel movements per week
  • Loos stool not present and insufficient criteria for IBS
43
Q

Rome II criteria for constipation in infants and children

A
  • Pebble-like, hard stools for a majority of bowel movements for at least 2 weeks
  • Firm stool less than or equal to 2 times per week for at least 2 weeks
  • No evidence of structural, endocrine, or metabolic disease
44
Q

Describe the prevalence of constipation in North America and the groups of people affected by it

A

NA prevalence ~15%

  • Women >> men (3:1)
  • Nonwhites > whites
45
Q

Reasons why women experience constipation more often than men

A
  • Longer coloncs, slower transit (36h vs. 29h)
  • Pregnancy can exacerbate
46
Q

7 risk factors for constipation

A
  • Increasing age
  • Low-fiber, Western-style diet
  • Decreased physical activity
  • Low income, socio-economic status
  • Limited education
  • History of sexual abuse
  • Depression
47
Q

What must constipation be dinstinguished from?

A

Obstructed defecation syndrome (i.e. rectal prolapse, non-relaxing puborectalis, etc…)

48
Q

Number one cause for constipation

A

Lifestyle neglect

49
Q

Example of an endocrine cause for constipation

A

Hypothyroidism

50
Q

Examples of medications that can cause constipation

A
  • Narcotics
  • Anti-cholinergics
  • Anti-psychotics
51
Q

Examples of neurogenic causes of constipation

A

Central vs. peripheral; i.e. slow-transit constipation, Chagas’ disease)

52
Q

Examples of psychological causes of constipation

A

Depression and anorexia

53
Q

4 treatment principles of constipation

A
  • Seek to identify the underlying cause
  • Rule out mechanical obstruction – combination of clinical history and/or imaging
  • Strongly consider a full colonoscopy to rule out neoplasm
  • In younger patients, lifestyle neglect is #1 cause – can proceed with dietary changes +/- adjuncts
54
Q

What is the number one reason for admittance to a nursing home?

A

Recal incontinence

55
Q

Describe the groups of people affected by fecal incontinence and the prevalence

A
  • 2 - 18% of population affected
  • 50% of nursing home residents
56
Q

3 things that are important to define in the setting of fecal incontinence

A
  • The cause of the incontinence (establish the diagnosis)
  • Degree of incontinence
  • Degree to which the patient is affected (impact)
57
Q

6 examples of “pseudo”-incontinence that must be ruled out if fecal incontinence is suspected

A
  • Urgency and stool loss from poor rectal compliance (IBD)
  • Overflow incontinences from stool impaction/ severe constipation
  • Poor hygiene
  • Anorectal STDs (gonorrhoea, chlamydia)
  • Prolapse (rectum and hemorrhoids)
  • Anorectal neoplasms
58
Q

5 Determinants of continence

A
  • Intact neurologic function
  • Anal sphincters
  • Proper function of pelvic floor musculature
  • Stool consistency and volume
  • Rectal compliance
59
Q

4 neurological causes of fecal incontinence

A
  • Spinal cord injury
  • Severe diabetes
  • Dementia
  • Defective RAIR
60
Q

2 ways the anal sphincters can be affected to lead to fecal incontinence

A

Trauma and rectal prolapse

61
Q

An example of how imporper function of pelvic floor musculature can lead to fecal incontinence

A

Prudendal nerve injury

62
Q

2 examples of fecal incontinence related to stool consistency and volume

A

Fecalomas and diarrhea

63
Q

2 examples of defective rectal compliance that can lead to fecal incontinence

A

Neoplasms and inflammatory conditions

64
Q

Number one cause of fecal incontinence

A

Obstetric

65
Q

3 risk factors for obstetric-related fecal incontinence

A
  • Forceps
  • Episiotomies
  • 1st baby
66
Q

3 obstetric events that can lead to pudendal nerve injury

A
  • Prolonged straining (2nd stage of labor)
  • Forceps
  • Big babies
67
Q

Frequency of anal tears in the obstetric setting

A

0.6 - 9% and may breakdown/weaken with time even post-repair

68
Q

4 categories of causes for fecal incontinence

A
  • Obstetric
  • Iatrogenic
  • Congenital malformations
  • Rectal prolapse
69
Q

3 iatrogenic causes of fecal incontinence

A
  • Fistulotomy
  • Sphincterotomy
  • Radiation proctitis
70
Q

3 congenital causes of fecal incontinence

A
  • Spina bifida
  • Myelomeningocele
  • Imperforate anus
71
Q

3 steps in evaluation of a patient with fecal incontinence

A
  • Detailed history and physical exam
  • Look for scarring, trauma from birthing, excoriation/skin changes from chronic soiling, patulous anus, associated conditions
  • Digital rectal exam for fecalomas, anal sphincter condition, anal squeeze
72
Q

3 specific aspects of the detailed history and physical exam for patients with fecal incontinence

A
  • Stool diary
  • Incontinence scale
  • Rule out diarrheal states and pseudo-incontinence
73
Q

4 diagnostic tools for a patient with fecal incontinence

A
  • Full colonoscopy
  • Endoanal ultrasound
  • Pudendal nerve terminal motor latency (PNTML)
  • Anal manometry
74
Q

Purpose of full colonoscopy for fecal incontinence patients

A

Rule out other lesions

75
Q

Best test to assess fecal incontinence

A

Endoanal ultrasound

76
Q

Aspects evaluated by endoanal ultrasound

A
  • Internal and external sphincters
  • Distance between the vaginal orifice, size of perineal body, anal musculature
77
Q

What is defined as an abnormal finding by endoanal ultrasound?

A

Perineal body thickness of less than 10 mm

78
Q

Purpose of PNTML for fecal incontinence patient

A

Checks the pudendal nerve for injury

79
Q

Normal range of pressure measured by anal manometry

A

40 - 70 mm Hg

80
Q

What does anal manometry check?

A

RAIR and rectal compliance

81
Q

2 steps of treatment for fecal incontinence

A
  • Estbliash the diagnosis and treat the underlying condition
  • Medical management
82
Q

4 types of medical treatments for fecal incontinence

A
  • Meds to normalize stool consistency
  • Conspitating agents
  • Biofeedback
  • Injectable sphincter-bulking agents (silicone-based)
83
Q

2 ways to normalize stool consistency

A
  • Bulking (by psyllium, for example)
  • Treatment of diarrhea and constipation (scheduled disimpactions if necessary)
84
Q

3 constipating agents

A
  • Loperamide (imodium)
  • Lomotil
  • Codeine
85
Q

Describe biofeedback

A

Visual and auditory feedback for pelvic physical therapy

86
Q

Benefits of biofeedback for fecal incontinence patients

A
  • 44% achieve complete continence
  • 76% achieve improved continence

by 3 months

87
Q

5 surgical options for fecal incontinence

A
  • Overlapping sphincteroplasty
  • Artificial bowel sphincter
  • Sacral nerve stimulatory (SNS)
  • Antegrade enema
  • Permanent colostomy
88
Q

How does an antegrade enema access the rectum?

A

By cecostomy button or appendix

89
Q

Benefit of antegrade enema

A

Large volume (3 - 4 saline enema) can clean colon for up to 48 hours

90
Q

When is permanent colostomy used?

A

When many modalities have failed

91
Q

Define overlapping sphincteroplasty

A

Surgical repair of damaged sphincters to reconstitue the anatomy

92
Q

Benefit of overlapping sphincteroplasty

A
  • Good initial results
  • ~50% remain continent to both solid and liquid stool at 5 years
  • Can repeat the surgery to “re-tighten” muscles
93
Q

Initial purpose of sacral nerve stimulation

A

Treatment for urinary incontinence

94
Q

Explain how sacral nerve stimulation works

A

Mechanism is unclear, but overal effect is increased resting tone by placing the stimulator by the 3rd sacral n. root

95
Q

Describe the artificial bowel sphincter

A

If the anal muscles are destroyed, an aritificial sphincter can be recreated with an inflatable cuff, with the pump place in scrotum/labium

96
Q

Problem with artificial bowel sphincter

A

High infection rates