Constipation (GI)

Question 1

What is chronic constipation?

Answer 1

Polysymptomatic heterogeneous disorder

Question 2

Define constipation.

Answer 2

Defecation that is unsatisfactory characterised by:

• infrequent stools
• difficult stool passage (straining/discomfort)
• infrequent and/or difficult defecation (seemingly incomplete)

Question 3

What is the difference between primary and secondary constipation?

Answer 3

• 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

Question 4

What are some types of primary constipation? (3)

Answer 4

• 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

Question 5

What is rectocele?

Answer 5

Associated with constipation - prolapse where the supportive wall of tissue between the rectum and vaginal wall weakens

Question 6

Which gender is constipation more common in?

Answer 6

F > M

Question 7

What is primary constipation caused by?

Answer 7

Most commonly due to poor diet (lack of fibre) or dehydration and insufficient exercise

Question 8

What is secondary constipation caused by? (8)

Answer 8

• colorectal cancer
• bowel obstruction
• diverticulosis
• diverticulitis
• haemorrhoids
• IBS
• hypothyroidism
• drug-induced (opioids) etc

Question 9

What is the main clinical feature of constipation?

Answer 9

Passage of infrequent hard stools

Question 10

What are the key diagnostic/clinical features of constipation? (5)

Answer 10

• infrequent stools
• difficult defecation
• tenesmus - sense of incomplete evacuation
• excessive straining
• hard stools

Question 11

What clinical features might be seen on examination of constipation?

Answer 11

• 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

Question 12

What are some risk factors for constipation?

Answer 12

• 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)

Question 13

What problem with the urinary system can constipation cause?

Answer 13

Outflow obstruction and trigger episodes of urinary retention in patients with enlarged prostates

Question 14

What examinations do we conduct for constipation?

Answer 14

• abdominal examination
• digital rectal examination

Question 15

What main investigation do we do for constipation?

Answer 15

Anal manometry to evaluate constipation or functional anorectal pain

Question 16

What 1st line investigations are done for constipation?

Answer 16

• microbiology: stool sample, quantitative faecal immunochemical test
• bloods: FBC, TFTs, U&Es, blood glucose
• imaging: abdominal x-ray
• special tests: barium enema

Question 17

What does FBC show for constipation?

Answer 17

Secondary cause e.g. iron deficiency anaemia

Question 18

What can TFTs show for constipation?

Answer 18

Hypothyroidism

Question 19

What could abdominal x-ray show for constipation?

Answer 19

Rectal masses, faecal impaction

Question 20

What can barium enema show for constipation?

Answer 20

• barium inserted via tube into intestine –> fluoresces on x-ray –> visualise structure of colon
• faecal impaction, rectal masses

Question 21

What red flags could prompt further investigation (e.g. colonoscopy) for constipation? (9)

Answer 21

• 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

Question 22

What are some differential diagnoses for constipation?

Answer 22

• 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

Question 23

What lifestyle changes do we recommend for constipation? (3)

Answer 23

• high fibre diet
• increase fluid and caloric intake
• exercise

Question 24

What medications can we give for constipation and what types are there?

Answer 24

• 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

Question 25

How do we treat opioid-induced constipation?

Answer 25

- 1st line: review opioid use + osmotic/stimulant laxative - 2nd line: peripherally acting mu-opioid receptor antagonist (e.g. methylnaltrexone) - 3rd line: lubiprostone

Question 26

How do we treat not opioid-induced constipation with symptoms <3 months?

Answer 26

- 1st line - treatment of any identified underlying cause - consider bulk/fruit-based laxatives and/or stool softener

Question 27

How do we treat not opioid-induced constipation with symptoms >3 months?

Answer 27

- 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

Question 28

How do we treat dyssnergic defecation constipation?

Answer 28

Biofeedback

Question 29

What are some complications of constipation?

Answer 29

- 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

Question 30

What is the prognosis of constipation like?

Answer 30

Medical therapy is fairly effective in relieving constipation symptoms