Mar1 M3-Defecatory disorders

Question 1

number 1 cause of institutionalization of elderly

Answer 1

fecal loss and fecal incontinence (often bc of dementia)

Question 2

inferior rectal artery vs hemorrhoidal supply

Answer 2

• inferior rectal artery comes from inferior pudendal artery (off iliac)
• hemorrhoidal supply from IMA

Question 3

rectum function and when disturbed

Answer 3

• rectum capacitance through series of reflex arcs

- Crohn’s or UC: rectal wall inflamed, edematous and no longer distends

Question 4

internal vs external anal sphincter

Answer 4

internal = tissue there insensate, SM, involuntary, has a resting tone
external = anoderm there is sensate, skeletal muscle, voluntary

Question 5

surgical anal canal and dentate line

Answer 5

above dentate line = hemorrhoid, insensate hindgut
below dentate line = ectoderm derived anoderm, sensate
*crypts and glands in anal canal

Question 6

anal transition zone (ATZ) def + fct

Answer 6

• transitional coacogenic epithelium
• IMPORTANT fct: sample, sense consistency of poop or if it’s a fart
• below ATZ, anoderm: sensate, non-keratinzed epithelium

Question 7

role of PSS innervation in the gut

Answer 7

-GIT motility
-continence and rectal capacitance
-pelvic fct
(cranio-vagal, caudal-sacral)

Question 8

SS role in the gut

Answer 8

• SLOWS colonic motility

- thoraco-lumbar

Question 9

contractions and peristalsis in the colon

Answer 9

• high amplitude contractions (HAC): 5-6x a day, occur with waking and after meal
• low amplitude contractions (LAC): related to meals and sleep-wake cycle
• segmental contractions (DON’T propagate)

Question 10

problems related to HAC and LAC imbalance

Answer 10

HAC > LAC = faster transit

LAC >HAC = slower transit (constipation, etc.)

Question 11

anatomic factors to maintain continence

Answer 11

• internal anal sphincter resting tone (45%)
• external (ONLY VOLUNTARY CONTINENCE) anal sphincter (30%)
• hemorrhoidal plexus (10-15%)

Question 12

functional factors to maintain continence

Answer 12

anorectal angle, puborectalis, flap-valve

Question 13

4 important reflex arcs in the bowel

Answer 13

• gastro-colic (food in mouth triggeres colonic motility and segmental contractions)
• recto-anal inhibitory reflex (rectal distension) (RAIR)
• recto-anal excitatory reflex (rectal distension) (RAER)
• bulbocavernosus reflex (S2,3,4)

Question 14

RAIR and RAER fct

Answer 14

• RAIR triggers relaxation of INTERNAL anal sphincter when poop is there
• RAER triggers EXTERNAL sphincter contraction when poop in rectum

Question 15

how normally inhibit defecation

Answer 15

• pressure receptors in rectal wall and pelvic side wall (not in rectum itself) trigger RAIR and RAER
• reflex arcs for rectum to distend and urge to defecate will pass

Question 16

normal things involved in defecation

Answer 16

1. valsalva maneuver (incr. abd pressure)
2. puborectalis muscle RELAXATION (opens anorectal angle, pelvic floor descent)
3. external sphincter relaxation

Question 17

(EXAM) pro-defecatory stimuli

Answer 17

• exercise (stimulates HAC)
• distension (bulky stools)
• waking up
• eating
• drugs (laxatives)

Question 18

risk factors for constipation

Answer 18

• increasing age
• low-fiber, Western diet
• less physical activity
• low SES
• limited education
• depression

Question 19

(IMPORTANT) number 1 cause of constipation

Answer 19

lifestyle neglect

Question 20

investigations in constipation patient

Answer 20

• hypothyroidism
• IBS
• meds
• neurogenic cause
• psychological (depression, anorexia, ..)

Question 21

problem in laxatives in constipation

Answer 21

can get tolerant and they don’t work anymore

Question 22

treatment principles in constipation

Answer 22

• consider colonoscopy
• rule out mechanical obstruction
• talk about lifestyle neglect
• need laxatives?

Question 23

(IMPORTANT) only time you consider indication for surgery in constipation

Answer 23

neurologic disorder of colonic failure (true slow-transit constipation), diagnosed by a Sitzmark study

Question 24

types of laxatives for constipation

Answer 24

• bulk laxatives (water, fiber, supplement)
• osmotic laxatives (non digested sugar, MgOH2)
• docusate sodium or Senekot (detergent, emollient: softens stool)

Question 25

best laxatives and downside

Answer 25

bulk laxatives (psyllium, fibers)
downside = fermented in bowel: get pain and gas

Question 26

fecal incontinence def

Answer 26

insufficient voluntary control of gas or stool (number 1 cause admission in nursing home). NOT A DX. is a symptom

Question 27

fecal incontinence: things to rule out

Answer 27

• inflam disorders like CD, UC causing poor rectal compliance
• overflow incontinence from severe constipation
• poor hygiene
• anorectal STDs (gonorrhoea, chlamydia)
• prolapse (rectum, hemorrhoids)
• anorectal neoplasms

Question 28

determinants of fecal continence (what can be the cause of incontinence)

Answer 28

• neurologic function (RAIR is absent in Hirschprung’s)
• anal sphincter fct (trauma, prolapse)
• pelvic floor musculature fct (pudendal nerve injury)
• stool consistency
• rectal compliance (neoplasms, inflam conditions)

Question 29

(EXAM) number 1 cause of fecal incontinence

Answer 29

-obstetrical trauma (damage later in life when muscle atrophy)
(other causes are pudendal nerve damage, iatrogenic, congenital malformations, rectal prolapse)

Question 30

(EXAM) best test for fecal incontinence

Answer 30

endoanal ultrasound

Question 31

what endoanal US does

Answer 31

measures structures of sphincter and rules out sphincter injury

Question 32

management of fecal incontinence

Answer 32

establish dx, treat underlying cause (normalize stool consistency), constipating agents

Question 33

fecal incontinence caused by damaged sphincter treatment

Answer 33

surgery: overlapping sphincteroplasty (repair of damaged sphincter)

Question 34

miscellaneous fecal incontinence treatments

Answer 34

• sacral nerve stimulator (put near the spine)

- artificial bowel sphincter (pump placed in scrotum or labium) if anal muscles are destroyed