constipation Flashcards
what is constipation defined as ?
either difficulty passing stool
or passing stool too infrequently ( for a period of 4 days or more )
what are the two types of constipation according to cause ?
primary : functional
secondary : organic
what are the different causes of functional constipation ?
normal transient
slow transient
pelvic floor dysfunction
what facilitates the removal of water from faeces ?
CFTR channel
what is the cause of normal transient constipation ?
decreased water and fiber content
what is the clinical application of the CFTR gene ?
CF patients - have dry stools and lead to constipation
cholera toxin - stimulates CFTR and causes diarrhea
lubi or amiprostone - a CFTR analogue causing diarrhea
what is the criteria for the diagnosis of constipation ?
according to the Rome IV criteria :
at least 2 symptoms of the following 6 , for the past 6 months :
1- fewer than 3 spontaneous bowel movements per week
2- straining for more than 25% of defecation attempts
3- lumpy or hard stools
4- sensation of anorectal obstruction or blockage
5- sensation of incomplete defecation
6- manual manoeuvers required
what are the two characteristic movements associated with colonic movement ?
1- repetitive non propulsive contractions
2- high amplitude propagated contractions HAPC which usually happen iin the morning
which colonic movement is decreased during constipation ?
HAPC
what is the major movement neurotransmitter ?
serotonin
5HT3 and 5HT4
what is the clinical application of 5HT in colonic motility ?
carcinoid syndrome , where theerre is too much seretonin and hence the diarrhea
what drugs are associated with 5HT ?
5HT4 agonist - prucalopride
5HT3 agonist - ondansetron ( antiemetic)
what is the anatomy associated with the pelvic floor ?
1- internal anal sphincter - not under conscious control
2- external anal sphincter
3- puborectalis ( relaxes with defecation)
what is the rectoanal inhibitory reflex ?
RAIR - rectal distention by stool or gas induces relaxation of the internal anal sphincter
what is the clinical application of RAIR ?
hirschsprung disease , a congenital disorder where the internal anal sphincter fails to relax in response to distention by stool or gas
in the diagnosis of the cause of constipation what is the algorithm ?
history and examination
baseline labs
therapeutic trial of fiber/laxatives
inadequate response then anorectal manometry
what are the the results that can be concluded from anorectal manometry ?
1- if normal , determine the colonic transit
2- if inconclusive - perform barium or MR enema
3- if abnormal - defecatory disorder
what are the alarming symptoms associated with constipation ?
unexplained weight loss
unexplained anemia
acute constipation in elderly
inability to pass flatus
hematochezia
what must be done during examination for a patient complaining of constipation ?
digital examination during valsalva maneuver
what lab investigations should you ask for for a constipated patient ?
CBC
TFT
electrolyte panel
what is the most useful imaging modality in acute setting of constipation ?
plain abdominal xray
when do we move on to physiologic testing ?
if there is no response to laxatives or fiber trial
what is anismus ?
dyssynergic defecation , inadequate widening of the anorectal angle
what is the first linee mnmnt for norrmal or slow transit constipation ?
laxatives
what is the first line management for defecatory disorder ?
pelvic floor training , dietitian and psychology
if no improvement - repeated balloon expulsion
what does a defecatory disorder actually mean ?
failure of normal relaxatioion of the puborectalis and the xternal anal sphincter
which individuals are more commonly to have slow transit constipation ?
young women who have infrequent bowel movements
may be associated with failure of meal stimulated colonic motility
