Constipation (GI) Flashcards
What is chronic constipation?
Polysymptomatic heterogeneous disorder
Define constipation.
Defecation that is unsatisfactory characterised by:
- infrequent stools
- difficult stool passage (straining/discomfort)
- infrequent and/or difficult defecation (seemingly incomplete)
What is the difference between primary and secondary constipation?
- primary constipation - disordered regulation of colonic and anorectal neuromuscular function + brain-gut neuro-enteric function
- issues with the gut itself
- secondary constipation - metabolic disturbances, medicines, neurological disorders, spinal cord lesions, primary diseases of the colon e.g. cancer
- due to other conditions/exogeneous substances
What are some types of primary constipation? (3)
- slow-transit constipation: inadequate defecatory propulsion caused by primary dysfunction of colonic smooth muscle (myopathy) and/or its innervation (neuropathy)
- dyssynergic defecation: paradoxical contraction/inadequate relaxation of the pelvic floor muscles during attempted defecation, e.g. due to faulty toilet training, behavioural problems, or parent-child conflicts
- irritable bowel syndrome-constipation: altered autonomic regulation, release of NTs e.g. serotonin or altered functions of gut receptors
What is rectocele?
Associated with constipation - prolapse where the supportive wall of tissue between the rectum and vaginal wall weakens
Which gender is constipation more common in?
F > M
What is primary constipation caused by?
Most commonly due to poor diet (lack of fibre) or dehydration and insufficient exercise
What is secondary constipation caused by? (8)
- colorectal cancer
- bowel obstruction
- diverticulosis
- diverticulitis
- haemorrhoids
- IBS
- hypothyroidism
- drug-induced (opioids) etc
What is the main clinical feature of constipation?
Passage of infrequent hard stools
What are the key diagnostic/clinical features of constipation? (5)
- infrequent stools
- difficult defecation
- tenesmus - sense of incomplete evacuation
- excessive straining
- hard stools
What clinical features might be seen on examination of constipation?
- abdominal mass (RLQ/LLQ) on palpation - may indicate secondary cause
- anorectal lesions/abnormalities on DRE
- relaxation of the external anal sphincter and/or puborectalis muscle, together with perineal descent on defecation manouevre - abnormal may suggest evacuation disorder e.g. dyssynergic defecation
What are some risk factors for constipation?
- female
- age>65
- African ancestry
- lower socioeconomic status
- Fx
- sedentary lifestyle
- low fibre intake, inadequate calories/fluid (hardens stool, reduces transit)
- surgical procedures + childbirth
- medications - opiates, calcium channel blockers, TCAs (co-codamol commonly causes constipation as side effect)
What problem with the urinary system can constipation cause?
Outflow obstruction and trigger episodes of urinary retention in patients with enlarged prostates
What examinations do we conduct for constipation?
- abdominal examination
- digital rectal examination
What main investigation do we do for constipation?
Anal manometry to evaluate constipation or functional anorectal pain
What 1st line investigations are done for constipation?
- microbiology: stool sample, quantitative faecal immunochemical test
- bloods: FBC, TFTs, U&Es, blood glucose
- imaging: abdominal x-ray
- special tests: barium enema
What does FBC show for constipation?
Secondary cause e.g. iron deficiency anaemia
What can TFTs show for constipation?
Hypothyroidism
What could abdominal x-ray show for constipation?
Rectal masses, faecal impaction
What can barium enema show for constipation?
- barium inserted via tube into intestine –> fluoresces on x-ray –> visualise structure of colon
- faecal impaction, rectal masses
What red flags could prompt further investigation (e.g. colonoscopy) for constipation? (9)
- blood in stool
- significant unexplained weight loss
- Fx of colorectal carcinoma, IBD
- iron deficiency anaemia
- palpable abdominal mass
- rectal prolapse
- sudden onset of new change in bowel habit
- persistent constipation despite treatment
- reduced stool calibre
What are some differential diagnoses for constipation?
- anal fissure - rectal pain, bleeding, excessive straining
- medicine-induced constipation - opiates, CCBs, antipsychotics
- hypercalcaemia
- hypothyroidism
- diabetes mellitus
- spinal cord lesion
- colonic stricture
- colon cancer
- Parkinson’s
- dehydration
What lifestyle changes do we recommend for constipation? (3)
- high fibre diet
- increase fluid and caloric intake
- exercise
What medications can we give for constipation and what types are there?
- bulk laxatives & stool softeners - preferred (bulk laxatives produce gas, stool softeners = bitter taste, nausea, diarrhoea, cramping)
- osmotic laxatives e.g. lactulose, polyethene glycol compounds, magnesium containing laxatives (–> bloating, diarrhoea, pain, flatulence, N&V)
- stimulant laxatives e.g. senna, bisacodyl - if persistent symptoms after 6wk osmotic laxatives
- prunes - natural alternative to laxatives
How do we treat opioid-induced constipation?
- 1st line: review opioid use + osmotic/stimulant laxative
- 2nd line: peripherally acting mu-opioid receptor antagonist (e.g. methylnaltrexone)
- 3rd line: lubiprostone
How do we treat not opioid-induced constipation with symptoms <3 months?
- 1st line - treatment of any identified underlying cause
- consider bulk/fruit-based laxatives and/or stool softener
How do we treat not opioid-induced constipation with symptoms >3 months?
- 1st line - treatment of any identified underlying cause
- 2nd line - osmotic and/or stimulant laxative
- 3rd line - guanylate cyclase-C agonist/lubiprostone/prucalopride/vibrating capsule
How do we treat dyssnergic defecation constipation?
Biofeedback
What are some complications of constipation?
- anal fissure (forceful expulsion of hard stool = trauma and injury)
- haemorrhoids (excessive straining –> damage)
- faecal impaction
- rectocele (anterior bulging of rectal wall towards vagina)
- faecal seepage
- overflow diarrhoea
- acute urinary retention
What is the prognosis of constipation like?
Medical therapy is fairly effective in relieving constipation symptoms
