Constipation, Hirschprung, Megacolon

Question 1

Definition of constipation:

Answer 1

Infrequent BM <3/wk for 12 mo 
AND at least 25% of time:
  straining
  feeling of incomplete evacuation
  hard stool

Question 2

In normal colon, motor function depends on contraction of

Answer 2

circular layer of smooth muscle

Question 3

3 patterns of contractions:

Answer 3

short duration
long duration
giant migrating complexes

Question 4

How are short duration colonic contractions characterized?

Answer 4

stationary motor contr, present over short areas of colon + persisting for <15s

Question 5

What is the physiologic function of short duration colonic contractions?

Answer 5

mixing of fecal material and extraction of water

Question 6

How are long duration colonic contractions characterized?

Answer 6

stationary or propagating (short distances) contractions, which may travel in orad or aboral direction

Question 7

What is the physiologic function of long duration colonic contractions?

Answer 7

Assists in mixing and local propulsion of feces

Question 8

long duration colonic contractions cause migration towards:

Answer 8

rectum in distal colon

Question 9

How are giant migrating complexes of the colon characterized?

Answer 9

aboral propagating over extended distances

Question 10

What is the physiologic purpose of giant migrating complexes of the colon?

Answer 10

causes mass movement of feces

Question 11

Giant migrating complexes of the colon normally occur ____ (how freq?), and may be precipitated by:

Answer 11

1-2 times per day

colonic distention

Question 12

How does food affect colonic motility?

Answer 12

causes increased segmental activity

Question 13

Gastro-colic reflux may be mediated by:

Answer 13

CCK

Question 14

Motility in response to food intake is proportional to:

Answer 14

caloric content of meal

Question 15

CCK causes:

Answer 15

increased frequency & amplitude of segmental contractions

Question 16

PgF stimulates:

Answer 16

longitudinal muscle contraction

Question 17

PgE inh:

Answer 17

circular muscle contraction

Question 18

Serotonin mediates:

Answer 18

intestinal peristalsis
secretion in GI tract
modulation of pain perception

Question 19

Serotonin is released by:

__% of serotonin is located in GIT

Answer 19

enterochromaffin cells

80

Question 20

What do 5HT3-R antagonists treat?

Answer 20

IBS pain

functional dyspepsia

Question 21

2 types of constipation?

Answer 21

functional

IBS-C

Question 22

Constipation is more common in pts with:

Answer 22

little daily physical activity
low income
poor education

Question 23

Constipation: Epidemiology

Answer 23

F>M

~65 y/o

Question 24

Major causes of chronic constipation?

Answer 24

neuropathic disorders
IBS-C
drugs
pregnancy
hyper/hypo-Ca
hypothyroidism
idiopathic

Question 25

Drugs associated with constipation?

Answer 25

``` analgesics anticholinergics Fe-supplements Cation-containing (Al) CCB neurally-active ```

Question 26

What lifestyle characteristics cause constipation in elderly?

Answer 26

dehydration low calorie diet low fiber diet immobility

Question 27

Constipation: Pediatric Etiology

Answer 27

95% functional 5% organic (which includes lead intoxication)

Question 28

Functional constipation: Epidemiology? Symptoms?

Answer 28

infants + pre-school age 2wks pebble-like, hard stools

Question 29

Functional fecal retention: Epidemiology? Etiology?

Answer 29

common cause of chronic constipation infancy to 16 years old fear and toilet refusal

Question 30

What should you rule out when diagnosing constipation?

Answer 30

thyroid disorders or electrolytes problem

Question 31

What tests would you perform to dx constipation?

Answer 31

Colonoscopy or Barium Enema Colon transit of markers Anorectum Manometry

Question 32

Which patients with constipation should you get lab data for?

Answer 32

``` rectal bleeding wt loss of ≥10 pounds family hx of colon CA or IBD anemia (+) fecal occult blood ```

Question 33

What labs should you perform for constipation?

Answer 33

``` CBC glu creatinine Ca TSH ```

Question 34

Plain films of the abdomen help in the diagnosis of:

Answer 34

Megacolon | Impaction

Question 35

Colon Transit Study: Methods? Normal results?

Answer 35

methods: take Sitzmarks capsule, check Xray on day 5 normal: >80% ring markers passed by day 5

Question 36

Severe Idiopathic Chronic Constipation more commonly affects (M, F)

Answer 36

F

Question 37

Severe Idiopathic Chronic Constipation: | Symptoms?

Answer 37

infrequent defecation, excessive straining when defecating, or both

Question 38

Sitz marker study: | Colonic inertia results?

Answer 38

delayed passage of marker through proximal colon no increase in motor activity after meals or with laxatives

Question 39

Sitz marker study: | Outlet delay?

Answer 39

markers move normally through the colon but stagnate in rectum (more common in pelvic floor dyssenergia)

Question 40

How is the pelvic floor involved in normal defecation?

Answer 40

puborectalis, ext/int sphincter relax increased intraabdominal pressure inhibition of colonic segmenting activity

Question 41

What causes dyssynergic defecation?

Answer 41

failure to relax or inappropriate contraction of the puborectalis and external anal sphincter muscles

Question 42

abnormalities that can produce severe idiopathic chronic constipation:

Answer 42

Slow transit constipation Dyssynergic defecation Irritable bowel syndrome

Question 43

What is Hirschsprung Disease?

Answer 43

Congenital disorder characterized by: - -obstipation from birth - -colonic dilatation proximal to a spastic, non-relaxing and nonpropulsive segment of distal bowel

Question 44

Hirschsprung Disease/Congenital Aganglionic Megacolon | Epidemiology?

Answer 44

Males > female : 4:1 10% of cases in Down’s Syndrome Most cases: sporadic, a few familial

Question 45

Hirschsprung Disease/Congenital Aganglionic Megacolon | Pathogenesis?

Answer 45

Absence of ganglion cells in submucosa and musc wall of large bowel

Question 46

Hirschsprung Disease/Congenital Aganglionic Megacolon is caused by what genetic defects?

Answer 46

Heterogeneous defects in genes regulating: - migration + survival of neuroblasts - neurogenesis - receptor TK activity

Question 47

What causes mortality in Hirschsprung Disease?

Answer 47

Superimposed enterocolitis with fluid and electrolyte disturbances perforation with peritonitis

Question 48

What parts of the bowel are involved in Hirschsprung Disease/Congenital Aganglionic Megacolon?

Answer 48

rectum sigmoid (usually) entire colon = rarely

Question 49

What is the consequence of the abnormalities present in Hirschsprung Disease/Congenital Aganglionic Megacolon?

Answer 49

functional obstruction progressive dilation and hypertrophy proximal to aganglionosis later: massive distension outruns hypertrophy, wall becomes thinned + ruptures

Question 50

Hirschsprung Disease/Congenital Aganglionic Megacolon: | Clinical presentation?

Answer 50

- -failure to pass meconium - -obstructive constipation with occasional passage of stool - -bouts of diarrhea + abdominal distention

Question 51

Gold standard for Hirschsprung Disease/Congenital Aganglionic Megacolon diagnosis?

Answer 51

rectal biopsy showing absence of ganglionic cells

Question 52

Treatment of Hirschsprung Disease/Congenital Aganglionic Megacolon?

Answer 52

Surgical resection of the aganglionic segment of bowel | Sphincter function is generally preserved

Question 53

``` Acquired Megacolon (“Toxic Megacolon”): Infectious causes? ```

Answer 53

Clostridium difficile pseudomembranous colitis Chagas Disease: trypanosomes invade bowel wall and destroy enteric plexus

Question 54

``` Acquired Megacolon (“Toxic Megacolon”): Non-Infectious causes? ```

Answer 54

Inflammatory bowel disease Obstruction (tumor or inflammatory stricture) Functional disorder associated with pyschiatric disease and medication

Question 55

Can Acquired Megacolon be fatal?

Answer 55

YES!

Question 56

Anorectal Malformations: Epidemiology? Treatment?

Answer 56

1:3000 live births surgery

Question 57

Anorectal Malformations: | Pathogenesis (3 possible)?

Answer 57

Failure of urorectal septum formation in cloaca (week 7) failure of anal membrane opening (week 8) malformations in urinary tract and/or trisomy 21