Constipation and Megacolon Flashcards
What are the short duration colonic contractions?
stationary motor contractions, prseent over short areas of colon, causes mixing of fecal material and extraction of water, persists for less than 15 seconds
What are long duration colonic contractions?
may be stationary or propagate for short distances, may travel in orad or aboral direction
assists in mixing and local propulsion of feces
migrates towards rectum in distal colon
What are the giant migrating complexes of the colon?
propagates aborally over extended distances, causes mass mvmt, normally occuring 1-2 times.day, may be precipitated by colonic distention
What mediates the gastrocolic reflex?
cck, in response to food intake,
What is the role of CCK in colonic motility?
causes increased frequency and amplitude of segmental contractions
WHat is the role of Pg F in colonic motility
stimulated longitudinal muscle contraction
What is the role of PgE in colonic motility
inhibits circular muscle contraction
What is the role of serotonin in colonic motility
mediates intestinal peristalsis and secretion in GI tract as well as modulation of pain perception
What releases serotonin?
enterochromaffin cells
What is the epidemiology of constipation?
12-19%
more common in little physical acitivty, low income and poor education, over 65 years of age and women
What is the usual cause of pediatric constipation?
constipation (functional)
What lab tests should you order when evaluating constipation?
CBC, glucose, creatinine, calcium, TSH
what are sitzmarks?
they are a capsule of 24 radioopaque markers. if over 80% of markers are passed by day 5, the colon transit normal. also can tell you where there is a problem.
what is pelvic floor dyssynergia?
ineffective defecation associated with a failure to relax, or inappropriate contraction of, the puborectalis and eas muscles.
What is lubiprostone?
a chloride channel activator
what is hirschsprung dz?
congential disorder characterized by obstipation from birth and colonic dilatation proximal to a spastic, non-relaxing and nonpropulsive segment of distal bowel.
What is the epidemiology of hirschsprung dz
males, 10% of down syndrome cases, most cases sporadic
What is the pathogenesis of hirschsprung dz?
absence of ganglion cells in large bowel, function obstruction and proximal dilatation
What parts of involved in hirschsprung dz? not involved?
always involved is rectum, rectum and sigmoid in most cases.
what is the clinical presentation of hirschsprung dz?
failure to pass meconium
obstructive constipation, occasional passage of stool
bouts of diarrhea and abdominal distention
what is the ddx for acquired megacolon?
c. difficile IBs (uc or chrons dz) obstructino function disorder ie psychiatric chagas dz: trypanosomes destroying enteric plexus
What drugs are associated with megacolon
psychiatric drugs
what do yousee on rectal biopsy of hirschsprung dz?
nerve without ganglion cells (definitive dx)
70 wf htn high cholesterol smoking hypothyroid, br ca, diabetes, osteoporsis, lumbar fracture, MI rectal bleeding 7 yrs ago with diverticulitis. ER with constipation, used prunes, suppositories. cause if meds? cause if not meds?
if meds, opiates
if not meds, hypothyroidism or immobility
