Constipation Week 5 Flashcards
Constipation
is a common complaint in older adults & the most common digestive complaint in the general population
Rome III criteria: functional constipation is defined as any two of the following features:
- straining - lumpy hard stools - sensation of incomplete evacuation - use of digital maneuvers - sensation of anorectal obstruction or blockage with 25 percent of bowel movements - decrease in stool frequency (less than three bowel movements per week)
Rome III criteria requirements
need 2 of the features for the last 3 months with symptom onset 6 months prior to diagnosis
in older adults constipation may be associated with what?
fecal impaction and fecal incontinence
fecal impaction can cause
stercoral ulceration, bleeding, anemia
Stercoral ulceration is ?
the loss of bowel integrity from the pressure effects of inspissated feces
prevalence of constipation
prevalence of constipation in the older adult has not been well defined, but may be as high as 24- 50% of older adults, of whom 10- 18% use daily laxatives (especially community dwellings/ nursing homes)
Constipation in the older adult- why?
Primary colorectal dysfunction or secondary to several etiologic factors (often multi- factorial in older adults)
Primary colorectal dysfunction categorized into 3 broad sub- types:
slow transit constipation dyssynergic defecation irritable bowel syndrome
slow transit constipation
- prolonged delay in stool transit throughout the colon - Possibly primary dysfunction of colonic smooth muscle: myopathy, neuronal innervation (neuropathy), secondary to dyssynergic defecation
Dyssynergic defecation
- difficulty with or inability expelling stool from the anorectum - prolonged colonic transit time
irritable bowel syndrome
- predominant constipation (IBS-C) is characterized by abdominal pain with altered bowel habits. - may or may not have slow colonic transit or dyssynergia - many have visceral hypersensitivity
Constipation may be conceptually regarded as
disordered movement of stool through the colon or anorectum since, with few exceptions, transit through the proximal gastrointestinal tract is often normal. Slowing of colonic transit may be idiopathic or may be due to secondary causes.
what kinds of drugs are associated with constipation?
- analgesics - anticholinergics (antihistamines, antispasmodics, antidepressants, antipsychotics) - cation- containing agents (iron supplements, aluminum ie. antacids, sucralfate, barium - neurally active agents (opiates, antihypertensives, ganglionic blockers, vinka alkaloids, calcium channel blockers, 5HT3 agonists)
what receptor is at the root of this problem? (drugs causing constipation)
?? no idea
alarm features of constipation
hematochezia, weight loss of ≥10 pounds, a family history of colon cancer or inflammatory bowel disease, anemia, positive fecal occult blood tests, or acute onset of constipation in elderly persons
what can be considered when alarm features are absent?
empiric treatment (patient education, trial of dietary changes, and a trial of fiber) without diagnostic testing
An important part of the history includes defining ? regarding constipation
the nature and duration of constipation. Can do 2 week bowel diary to make sure they are actually constipated and not just thinking they are- Reassurances regarding the broad range of normal bowel frequency may be all that is necessary in some cases.
history should also focus upon
identifying secondary causes of constipation. (Most patients with idiopathic constipation are otherwise asymptomatic.)
A recent and persistent change in bowel habits, if not associated with a readily definable cause of constipation (eg, medications) should
prompt an evaluation to exclude structural bowel changes or organic diseases, especially in older adults. A diagnosis of functional constipation should be considered only after these other diseases have been excluded.
general physical examination is not helpful in most patients presenting with chronic constipation- instead what is useful? and why?
a rectal exam: - can identify fissures or hemorrhoids which may be caused by constipation, or which can be painful and thereby lead to voluntary stool retention and secondary constipation - A gaping or asymmetric anal opening may suggest that a neurologic disorder is impairing sphincter function - Responses of the puborectalis and external anal sphincter muscles may be evaluated by asking the patient to strain during the rectal examination; this is particularly useful in identifying patients with possible dyssynergic defecation
Normal defection involves the:
coordinated relaxation of the puborectalis and external anal sphincter muscles, together with increased intraabdominal pressure and inhibition of colonic segmenting activity
But in patients with dyssynergic defecation:
ineffective defecation is associated with a failure to relax, or inappropriate contraction of, the puborectalis and external anal sphincter muscles. This narrows the anorectal angle and increases the pressures of the anal canal so that evacuation is less effective. Relaxation of these muscles involves cortical inhibition of the spinal reflex during defecation; so, this pattern may represent a conscious or unconscious act.
The pathogenesis of dyssynergic defecation
is not completely understood but is probably multifactorial. It is thought to be an acquired, learned dysfunction rather than an organic or neurogenic disease.
DRE: examiner places the left hand on the patient’s abdomen to assess the push effort while the patient bears down, as if having a bowel movement. Normally- what happens?
the contraction of the abdominal muscles is accompanied by relaxation of the external anal sphincter and puborectalis muscles and perineal descent
But in patients with dyssynergia
there may be an inability to contract the abdominal muscles, inability to relax the anal sphincter, paradoxical contraction of the anal sphincter, or the absence of perineal descent
Work up for patients with red flags- (hematochezia, weight loss of ≥10 pounds, a family history of colon cancer or inflammatory bowel disease, anemia, or positive fecal occult blood tests, as well as a person with short-term history of constipation w/o obvious explanation)
Lab data- CBC, serum glucose, creatinine, calcium, and thyroid-stimulating hormone Radiography Endoscopy
plain films of the abdomen can detect what?
significant stool retention in the colon and suggest the diagnosis of megacolon
In patients without alarm symptoms or suspicion of organic disease, if the history and physical examination and a trial of conservative management do not reveal the cause of chronic constipation what should you do?
imaging study of the colon and rectum to exclude mass lesions, strictures, megacolon, and megarectum
A normal imaging study should lead to evaluation of
colonic transit and pelvic floor dysfunction
at least two of the following studies must be positive before diagnosing dyssynergic defecation
anorectal manometry; anal sphincter electromyography (EMG); defecography; and impaired balloon expulsion from the rectum
Physiologic testing: Defecography
are specialized tests of colorectal function, generally reserved for patients with chronic constipation who do not respond to therapy with lifestyle/ dietary modifications and a trial of bulk forming and osmotic laxatives (**know these pics**)
**Pics of abnormal defecogrpahy results
“You will see these again in a case study format/test question”
interventions 1-4
- lifestyle and dietary modification (fluid/ exercise)
- bulk laxatives (if #1 fails)
- a trial of osmotic laxatives (if #2 fails)
- colon secretagogues (lubiprostone) should be considered only when #3 fails (stimulant laxatives are efficacious, but chronic use should be avoided as the long -term safety in older adults is not known)
Enemas should only be used when?
to prevent fecal impaction in patients with several days of constipation
what may be helpful in patients with dyssynergic defecation?
biofeedback therapy
Timed toilet training that consists of
educationg patients to attempt a BM at least twice a day, usually 30 mins after meals, and to strain for no more than 5 minutes.
How does fiber make you go?
Increases stool bulk, which causes colonic distention and promotes stool propulsion
recommmended daily fiber intake
20- 25g per day. Increasing fiber intake may take several weeks to relive a patient’s constipation. Common problems with increasing fiber are bloating and flatulence.
bulk forming laxatives include
psyllium seed (Metamucil)
methylcellulose (Citrucel)
wheat dextrimn (benefiber)
how do bulk forming laxatives work
they absorb water and increase fecal mass. they are effective in increasing the frequency and softening the consistency of the stool with minimum adverse effects.
-can use alone or in combo with an increase in dietary fiber
evaluation algorithm for chronic constipation
treatment algorithm for slow transit constipation
treatment algorithm for defecating disorders
