Disorders of the Anorectum

Question 1

What are the functions of segmentation, compliance and peristalsis?

Answer 1

mixing, dehydration (segmentation)
storage (compliance)
mass movements (peristalsis)

Question 2

How do opioids cause constipation (mechanism)?

Answer 2

inhibits transmission by sensory neurons that would naturally communicate peristaltic relaxation via communication with inhibitory neurons

they can also decrease peristalsis and recreation of water

Question 3

When is colonic activity stimulated (times of day)?

Answer 3

stimulated on waking and eating meals- especially fatty meals

Question 4

What are the ROME III criterial for functional constipation?

Answer 4

includes 2+ of the following:

straining during at least 25% of defections
lumpy or hard stools at least 25% of time
sense of incomplete evacuation at least 25% of the time
manual maneuvers to facilitate defection at least 25% of the time
fewer than 3 defecations

also: loose stools rarely present w/o use of laxatives, and there are insufficient criteria for IBS

Question 5

Give examples of drugs that are associated with constipation.

Answer 5

antidepressants 
antipsychotics
opiates
calcium channel blockers
5HT3 antagonists

Question 6

Give an example drug of each class of drug: bulk agents, osmotic substances, diphenylmethanes, anthraquinone and secretory drugs.

Answer 6

bulk: psyllium
osmotic: PEG
diphenylmethanes: bisacodyl
anthraquinone: senna
secretory drugs: linaclotide (CFTR) or lubiprostone (Cl 2 channels)

Question 7

What are the 3 functional constipation classifications (transit patterns)?

Answer 7

normal transit
colonic inertia
outlet delay

Question 8

What are the causes of delayed transit in the colon and rectum respectively?

Answer 8

colon: decreased peristalsis because of increased segmentation
rectum: dyssynergia due to megarectum (lack of innervation)

Question 9

How does colonic inertia manifest in colon transit studies? Define colonic inertia.

Answer 9

particles are mixed throughout the whole colon with out sweeping movements to clear the colon

slow colonic transit, normal colon diameter and normal anorectal function

decreased response* in meals, cholinergic and laxatives

Question 10

What is the treatment of acute megacolon?

Answer 10

nasogastric suction
colonic decompression
correct electrolyte deficiencies
neostigmine
surgery

Question 11

What is a colonic volvulus?

Answer 11

abnormal twisting of bowel on itself, most common in the sigmoid (sigmoid) or cecum (LUQ), common in the elderly in the west and more common in Africa and Asia

Question 12

What is key diagnostically to remember about Hirschsprung disease?

Answer 12

IAS is always involved (determined by anorectal manometry), although it is not considered singly diagnostic

Males are effected more frequently than females, usually presents along with megarectum and megacolon

Question 13

What would be expected in a rectal biopsy in someone with Hirschprung Disease?

Answer 13

must be obtained >3cm proximal to the anal verge

absence of ganglion cells is consistent with HD, tissue stained with acetylcholinesterase can show the excessive ACE positive nerves in the submucosa

Question 14

What is dyssyndergia?

Answer 14

unconscious contraction of skeletal muscle that works against efforts to defecate- can be treated with biofeedback

Question 15

What are the anorectal mechanisms for continence?

Answer 15

storage elements: rectal compliance and colonic compliance

sensorimotor elements: anorectal angle, rectal sensation, internal and external anal sphincter

Question 16

Stool impaction can lead to what type of incontinence? Who is commonly impacted?

Answer 16

liquid stool seeps around the impaction and through anal canal, causing overflow incontinence

can also be caused by megarectum or blunting of rectal sensation

children, institutionalized elderly or those with dementia or psychosis

Question 17

What are different causes of reservoir incontinence? What populations are commonly affected?

Answer 17

decreased rectal compliance
rectal resection/tumor

commonly effected are IBD, radiation and rectal surgery patients

Question 18

What are different etiologies of internal sphincter incontinence? What populations are often affected?

Answer 18

weakness caused by trauma, degeneration and autonomic damage; often in middle aged or older adults that have scleroderma, sphincterotomy (due to fissures)

Question 19

What would the pattern of weakness in IAS weakness?

Answer 19

only resting pressure is affected

Question 20

What pattern of weakness is seen in EAS?

Answer 20

only squeeze pressure is effected

Question 21

Compare peripheral and central neurogenic causes of incontinence?

Answer 21

both will have weakness in squeeze and puborectalis muscle but only central will have decreased rectal sensation

Question 22

In functional impairment/dyssyndergistic defection what muscles are affected?

Answer 22

skeletal muscles: puborectalis and external sphincter