Constipation

Question 1

What are the 2 different types of constipation?

Answer 1

Primary constipation
Secondary constipation

Question 2

What may cause acute constipation?

Answer 2

Lifestyle changes
Hospitalisation
Immobility

Question 3

What are the different subtypes of primary constipation?

Answer 3

Normal transit constipation - symptoms of constipation despite normally colonic transit time
Defecatory disorders (outlet obstruction)
Slow transit constipation - constipation with slow colonic transit time

Question 4

What are the risk factors for primary constipation?

Answer 4

Lifestyle - poor diet, obesity, lack of physical activity
Genetic predisposition
Psychological and behavioural disorders
Alterations in normal gut flora, colonic dysmotility

Question 5

What are some of the causes of secondary constipation?

Answer 5

GI causes
Neurological causes
Metabolic causes
Connective tissue disorders
Constipation inducing medications

Question 6

What are some GI causes?

Answer 6

IBS-C
Coeliac disease
Mechanical bowel obstruction from anal cancer, strictures, volvulus etc

Question 7

What are some neurological causes?

Answer 7

Parkinson’s
Botulism
Spinal cord injury
MS
Stroke
Neuropathy

Question 8

What are some metabolic causes?

Answer 8

Electrolyte imbalance
Hypothyroidism
Hyperparathyroidism
Heavy metal poisoning

Question 9

What are some connective tissue disorders?

Answer 9

Scleroderma
SLE
Amyloidosis

Question 10

What are some constipation inducing medications?

Answer 10

Analgesics - opioids, NSAID
Antihypertensives
Bile acid resins
Neurotransmitter altering medications

Question 11

What is the pathophysiology behind altered stool consistency?

Answer 11

External factors such as lack of exercise or inadequate fluid and fiber intake (primary constipation)/internal factors such as changes within the colon or rectum (secondary constipation) → slow passage of stool → prolonged absorption of water by the bowel → dry, hard stool → painful defecation → sensation of incomplete and irregular bowel emptying → constipation

Question 12

What is the mechanism behind layered bowel motility?

Answer 12

Effective peristalsis of the bowel is controlled by intrinsic (e.g., myenteric plexus) and extrinsic (e.g., sympathetic and parasympathetic) innervation.
Any alteration in bowel innervation may lead to ineffective peristalsis.
Drugs (e.g., calcium channel blockers, opiates, antispasmodics, antidepressants) [10] → altered autonomic outflow and bowel muscle contraction [11]
Endocrine pathology (e.g., hypothyroidism) → downregulated bowel motility
Neurological pathology (e.g., spinal injury, enteric neuropathy) → disease or trauma of bowel innervation
Ineffective peristalsis → difficult passage of stool regardless of stool consistency → sensation of incomplete and irregular bowel emptying

Question 13

What is the approach to managing constipation?

Answer 13

Manage complications
Perform a clinical evaluation for constipation
If no abnormalities findings or red flags - obtain CBC to evaluate for anaemia
If abnormal findings or red flags - colonoscopy for colorectal malignancy. If secondary, treat underlying cause

Question 14

What is the clinical evaluation for constipation?

Answer 14

Identification of - red flags in adults
Rome 4 diagnostic criteria for primary constipation in adults
Risk factors for primary constipation
Clinical features or history suggestive of a secondary cause of constipation

Question 15

What are the red flags for constipation?

Answer 15

Blood in stool
Rectal bleeding
Recuts tenesmus (distressing and persistent but ineffective urge to empty rectum or bladder)
Clinically significant unintentional weight losss
Unexplained iron deficiency anaemia
Jaundice
Obstructive symptoms
Patients >50 years of age without previous screening for colorectal cancer
Abdominal or rectal mass
Sudden change in bowel habits
Family history of persistent GI conditions eg colorectal carcinoma

Question 16

What is the Rome 4 diagnostic criteria for primary constipation?

Answer 16

Symptoms onset more than or equal to 6 months prior

Presence of more than or equal to 2 of the following symptoms in at least 25% of bowel movements over 3 months - passage of spontaneous bowel <3 times/week
Passage of hard or lumpy stool
Sensation of anorectal obstruction
Sensation of incomplete evacuation
Straining during attempts to defecate
Manual aid to evacuate stool

Loose stools are rarely present except when laxatives are used

Rom 4 criteria for IBS are not met

Question 17

What should be looked for during a physical examination?

Answer 17

Abdominal examination to assess for GI pathology
Inspection of perineum and anus for anal fissures and hemorrhoids. Test for anal wink reflex - absence suggests a neurological condition
Digital rectal exam - check for masses and assess anal sphincter tone and duncrtion for signs of pelvic floor dyssnergia

Question 18

What are the diagnostic tests for primary constipation?

Answer 18

Not routinely needed if Rome 4 criteria as is met

To evaluate for secondary constipation - CBC, BMP, blood glucose levels and HbA1c
Thyroid function tests
Serum PTH levels and ionised calcium
Serum magnesium

Colonoscopy - indications - red flags in constipation, age >50

Anorectal function test - evaluate for defecatory disorders

Colon transit studies - differentiate between normal transit and slow transit constipation

Question 19

What is the first line approach for treatment?

Answer 19

High fibre diet, increased fluid intake and exercise, laxatives, healthy bowel habits

Question 20

What is the second line approach?

Answer 20

Begin with osmotic laxatives
If symptoms persist, add a short course of stimulant laxative

Question 21

How much fibre is recommended?

Answer 21

20-35g per day

Question 22

What are the healthy bowel habits doctors recommend to patients?

Answer 22

Schedule toileting for 10-15 minutes in the morning and roughy; 30 minutes after each meal to coincide with the gastrocolic reflex
Use a step stool while on toilet
Recognise and respond to urges to defecate

Question 23

What are the considerations for laxatives?

Answer 23

Those taking bulk forming or osmotic laxatives should be instructed to ensure adequate water consumption
Cbhroni9c osmotic laxative may lead top hypokalemia and metabolic alkalosis

Question 24

When d should stimulant laxatives be prescribed?

Answer 24

For short term use only
Taken approx 30 minutes after a meal (if you want to see the actual drug names look at amboss’ list on constipation under treatment)

Question 25

What is the function of intestinal secretagogues?

Answer 25

A group of drugs that improve colonic transfer time by increasing intestinal secretion of water, bicarbonate and chloride

Question 26

What are the adverse effects of intestinal secratagogues?

Answer 26

Diarrhoea
Nausea

Question 27

What are the clinical features of fecal impaction? a

Answer 27

Inability to defecate for days or weeks
Normal bowel sounds
Distended, tympanic abdomen
DRE - hard, impacted stools distending the rectum
Tenesmus

Question 28

What are the diagnostics for fecal impaction?

Answer 28

Clinical diagnosis
Abdominal X-ray - findings are dilated bowel loops, fecal shadows in the colon and rectum, air fluid levels may be visible

Question 29

What is the treatment for fecal impaction?

Answer 29

Rule out bowel perforation
Manual disimpaction
Administer osmotic enema
Consider addition off stimulatory suppositories
Prevention of reoccurrence

Question 30

What are the clinical features for opioid induced constipation?

Answer 30

Recent initiation of an opioid or dose adjustment
New or worsening constipation
Fecal impaction may be present
Physical examination typically normal

Question 31

What are the diagnostics for opioid induced constipation

Answer 31

Clinical diagnosis
Rome 4 criteria for OIC -
Recent initiation of opioid treatment or a dose increase
AND ≥ 2 of the characteristic clinical features of functional constipation:
Passage of spontaneous bowel movement < 3 times/week
Passage of hard or lumpy stool (more than 25% of defecations)
Sensation of anorectal obstruction/blockage (more than 25% of defecations)
Manual aid to evacuate stool necessary (more than 25% of defecations)
Straining during attempts to defecate (more than 25% of defecations)
Sensation of incomplete evacuation (more than 25% of defecations)
Loose stools are rarely present without the use of laxatives
Consider x-ray of the abdomen to rule out fecal impaction

Question 32

What is the treatment for opioid induced constipation?

Answer 32

Similar to the treatment of primary constipation; see “Treatment.”
Identify and treat any underlying organic cause.
Lifestyle and dietary modification
Evaluate the need for opiate therapy and discontinue/reduce dose if appropriate.
Medical therapy
Laxative therapy
Osmotic laxative
and/or stimulant laxative
Options for laxative-refractory OIC:
Peripherally acting μ-opioid receptor antagonists

Question 33

What are the complications of constipation?

Answer 33

Fecal incontinence
Fecal impaction, which may lead to bowel obstruction, or rarely, bowel perforation
Anal fissures
Hemorrhoids
Megacolon
Urinary retention
Pelvic floor damage in women
Rectal prolapse