Clinical Notes : Gastroenterology

208. Constipation in adults

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  • Constipation is a symptom-based disorder which describes defecation that is unsatisfactory because of infrequent stools, difficulty passing stools, or the sensation of incomplete emptying.

    • The Rome IV diagnostic criteria for constipation include spontaneous bowel movements occurring less than three times a week.

    • Stools are often dry, hard, or lumpy, and may be abnormally large or small.

    • In reality, constipation is often defined as passage of stools less frequently than the person's normal pattern.


  • Chronic constipation usually describes symptoms which are present for at least 12 weeks in the preceding six months.


  • Faecal loading/impaction describes retention of faeces to the extent that spontaneous evacuation is unlikely.

    • Overflow faecal incontinence (previously known as 'encopresis' or 'bypass soiling') is leakage of liquid stool from the proximal colon around impacted faeces, where small quantities of stool may be passed frequently and without sensation.


  • Functional (primary or idiopathic) constipation is chronic constipation without a known cause. Three physiologic subtypes have been described, which may overlap:

    • Normal transit — this is the most common subgroup, where there is constipation with no time delay in passage of stool through the colon. 

    • Slow transit — prolonged delay in passage of stool through the colon.

    • Outlet delay (or 'obstructed defecation') — can be caused by pelvic floor dyssynergia (the pelvic floor muscles are uncoordinated and contract rather than relax during attempted defecation).



Risk Factors

  • Social

    • Low fibre diet or low calorie intake.

    • Difficult access to toilet, or changes in normal routine or lifestyle.

    • Lack of exercise or reduced mobility.

    • Limited privacy when using the toilet.


  • Psychological

    • Anxiety and/or depression.

    • Somatization disorders.

    • Eating disorders.

    • History of sexual abuse.


  • Physical

    • Female sex.

    • Older age.

    • Pyrexia, dehydration, immobility.

    • Sitting position on a toilet seat compared with the squatting position for defecation.


Secondary Causes

  • Drugs

    • Aluminium-containing antacids; iron or calcium supplements.

    • Analgesics, such as opiates and nonsteroidal anti-inflammatory drugs (NSAIDs).

    • Antimuscarinics, such as procyclidine and oxybutynin.

    • Antidepressants, such as tricyclic antidepressants; antipsychotics, such as amisulpride, clozapine, or quetiapine.

    • Antiepileptic drugs, such as carbamazepine, gabapentin, oxcarbazepine, pregabalin, or phenytoin.

    • Antihistamines, such as hydroxyzine.

    • Antispasmodics, such as dicycloverine or hyoscine.

    • Diuretics, such as furosemide; calcium-channel blockers, such as verapamil.


  • Organic causes

    • Endocrine and metabolic diseases:

    • Diabetes mellitus (with autonomic neuropathy). 

    • Hypercalcaemia and hyperparathyroidism. 

    • Hypermagnesaemia.

    • Hypokalaemia.

    • Hypothyroidism.

    • Uraemia.

    • Myopathic conditions:

    • Amyloidosis.

    • Myotonic dystrophy.

    • Scleroderma.

    • Neurological conditions:

    • Autonomic neuropathy.

    • Cerebrovascular disease. 

    • Hirschsprung's disease. 

    • Multiple sclerosis. 

    • Parkinson's disease. 

    • Spinal cord injury, tumours.

    • Structural abnormalities:

    • Anal fissures, strictures, haemorrhoids.

    • Colonic strictures (for example following diverticulitis, ischaemia, or surgery). 

    • Inflammatory bowel disease. 

    • Obstructive colonic mass lesions (for example due to colorectal cancer).

    • Rectal prolapse or rectocele.

    • Postnatal damage to pelvic floor or third degree tear.

    • Other:

    • Irritable bowel syndrome. 

    • Slow transit constipation.

    • Pelvic or anal dyssynergia.



  • Constipation may occur at any age but is more common in women, the elderly, and during pregnancy.

  • Assessment of a person with constipation should include:

    • Any red flag symptoms or signs that may suggest a serious underlying cause, such as colorectal cancer.

    • The person’s understanding of constipation and their normal pattern of defecation.

    • The frequency and consistency of stools, including symptoms of faecal impaction and/or incontinence.

    • Associated rectal, abdominal, or urinary symptoms.

    • The severity and impact of symptoms on daily life and functioning.

    • Any risk factors or secondary causes.

    • Any self-help measures or drug treatments tried.

    • Abdominal and internal rectal examination. 


Diagnostic Algotythm

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Diagnostic criteria for functional constipation

(criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis):

  1. Must include two or more of the following:

    • Straining during at least 25% of defecations

    • Lumpy or hard stools at least 25% of defecations

    • Sensation of incomplete evacuation at least 25% of defecations

    • Sensation of anorectal obstruction/blockage at least 25% of defecations

    • Manual manoeuvres to facilitate at least 25% of defecations (e.g., digital evacuation, support of the pelvic floor)

    • Less than three defecations per week.

  2. Loose stools are rarely present without the use of laxatives.

  3. There are insufficient criteria for irritable bowel syndrome (IBS).


Diagnostic criteria for IBS-constipation

(criteria fulfilled for the past 3 months with symptom onset 6 months prior to diagnosis):

  • Recurrent abdominal pain, on average, at least 1 day per week in the past 3 months associated with two or more of the following:

    1. Related to defecation.

    2. Associated with a change in frequency of stool.

    3. Associated with a change in form (appearance) of stool

      • More than one-fourth (25%) of bowel movements with Bristol stool form types 1 and 2

      • Less than one-fourth (25%) of bowel movements with Bristol stool form types 6 and 7.


Diagnostic criteria for functional defecation disorders

(criteria fulfilled for the past 3 months with symptom onset at least 6 months prior to diagnosis):

  1. The patient must satisfy diagnostic criteria for functional constipation.

  2. During repeated attempts to defecate, must have at least two of the following:

    • Evidence of impaired evacuation, based on balloon expulsion test or imaging

    • Inappropriate contraction of the pelvic floor muscles (i.e., anal sphincter or puborectalis) or <20% relaxation of basal resting sphincter pressure by manometry, imaging, or electromyography (EMG)

    • Inadequate propulsive forces, assessed by manometry or imaging.

i) Dyssynergic defecation

  • Inappropriate contraction of the pelvic floor or <20% relaxation of basal resting sphincter pressure with adequate propulsive forces during attempted defecation.

ii) Inadequate defecatory propulsion

  • Inadequate propulsive forces with or without inappropriate contraction or <20% relaxation of the anal sphincter during attempted defecation.


Diagnostic criteria for opioid-induced constipation:

  1. New or worsening symptoms of constipation when initiating, changing, or increasing opioid therapy that must include two or more of the following:

    • Straining during at least 25% of defecations

    • Lumpy or hard stools (Bristol stool form score 1-2) in at least 25% of defecations

    • Sensation of incomplete evacuation for at least 25% of defecations

    • Sensation of anorectal obstruction/blockage for at least 25% of defecations

    • Manual manoeuvres to facilitate at least 25% of defecations (e.g., digital evacuation, support of the pelvic floor)

    • Less than three spontaneous bowel movements per week.

  2. Loose stools are rarely present without the use of laxatives.


Treatment Algotythm

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The approach to treatment depends on whether the constipation is diagnosed as a primary or a secondary condition (e.g., medication-induced constipation, pregnancy, Parkinson's disease).


Secondary causes are treated appropriately.


In medication-induced constipation, the initial step is to withdraw the medication if possible.


Constipation in pregnant women is managed with fibre and laxatives, with consideration of withdrawal of iron supplements.


Initial management of primary constipation will depend on whether the presentation is acute (<3 months) or chronic (>3 months).


Initial management of acute constipation (when secondary causes are excluded) includes enemas, suppositories, large volume polyethylene glycol (PEG) solution (also known as macrogols), stimulant laxatives, or disimpaction with sedation may be required if there is faecal impaction.

If persistent, where faecal impaction is absent and secondary causes are excluded, the treatment is the same as for patients with chronic constipation.

Initial management of chronic constipation, irrespective of the cause, focuses on diet and lifestyle changes, ensuring adequate fibre intake and dietary modification.

If the condition persists, bulk laxatives and stool softeners are used. Potential underlying causes of the condition are also considered.

Choice of Lassatives

  • The aim of laxatives is to increase stool frequency or ease of stool passage by increasing stool water content (directly by osmotic or intestinal secretory mechanisms) or by accelerating bowel transit.



  • Bulk-forming laxatives (containing soluble fibre) act by retaining fluid within the stool and increasing faecal mass, stimulating peristalsis; also have stool-softening properties.

    • Ispaghula husk.

    • Methylcellulose.

    • Sterculia.


  • Osmotic laxatives act by increasing the amount of fluid in the large bowel producing distension, which leads to stimulation of peristalsis; lactulose and macrogols also have stool-softening properties.

    • Lactulose.

    • Macrogols (polyethylene glycols).

    • Phosphate and sodium citrate enemas.


  • Stimulant laxatives cause peristalsis by stimulating colonic nerves (senna) or colonic and rectal nerves (bisacodyl, sodium picosulfate).

    • Senna — hydrolyzed to the active metabolite by bacterial enzymes in the large bowel.

    • Bisacodyl and sodium picosulfate — hydrolyzed to the same active metabolite. Bisacodyl is hydrolyzed by intestinal enzymes; sodium picosulfate relies on colonic bacteria.

    • Docusate — a surface-wetting agent which reduces the surface tension of the stool, allowing water to penetrate and soften it. Also has a relatively weak stimulant effect.

  • Prokinetic laxatives

    • Prucalopride — a selective, high-affinity, serotonin (5HT4) receptor agonist, which stimulates intestinal motility.


Withdrawing treatment

  • Withdraw gradually over months.

  • Some people may need treatment for significantly longer.

  • No evidence that prolonged treatment leads to ‘lazy bowel’


Self-management advice

  • Refer to online sources of information and support :​









  • Eat a healthy, balanced diet and have regular meals:

    • the diet should contain whole grains, fruits (and their juices) high in sorbitol, and vegetables

      • fruits that have a high sorbitol content include apples, apricots, grapes (and raisins), peaches, pears, plums (and prunes), raspberries, and strawberries


Fruit and Vegetables : Food Fact Sheet


Access l


The Eatwell Guide 


  • Fibre intake should be increased gradually (to minimise flatulence and bloating)

    • adults should aim to consume 30 g of fibre per day

    • The beneficial effects of increasing dietary fibre may take several weeks


Fibre : Food Fact Sheet



  • Drink an adequate fluid intake, especially if there is a risk of dehydration


Fluid (water and drinks) : Food Fact Sheet



  • Increase activity and exercise levels, if needed

  • Maintain helpful toileting routines:

    • regular, unhurried toilet routine, giving time to ensure that defecation is complete

    • respond immediately to the sensation of needing to defecate

    • ensure that people with limited mobility have appropriate help to access the toilet and adequate privacy

    • ensure the person has access to supported seating if they are unsteady on the toilet.​

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BMJ Best Practice

Last Reviewed 23 Dec 2020

Last Updated 10 Sep 2020




National Institute for Health and Care Excellence, CKS

November 2020


Constipation: A Global Perspective

World Gastroenterology Organisation Global Guidelines.

November 2010


Evaluation and Treatment of Functional Constipation inInfants and Children: Evidence-Based RecommendationsFrom ESPGHAN and NASPGHAN

North American Society for Pediatric Gastroenterology, Hepatology and Nutrition

JPGN2014;58: 258–274


Tabbers MM, Boluyt N, Berger MY, et al.

Clinical practice: diagnosisand treatment of functional constipation.

Eur J Pediatr2011;170:955–63.


Mounsey, A. and Raleigh, M. and Wilson, A.

Management of constipation in older adults.

American Academy of Family Physicians 92(6), 500-504.



Woodward, S. Norton, C. and Chiarelli, P.

Biofeedback for treatment of chronic idiopathic constipation in adults (Cochrane Review).

Issue 3. John Wiley & Sons, Ltd. 2014.


Roque, M. V. and Bouras, E.P.

Epidemiology and management of chronic constipation in elderly patients.

Clinical Interventions in Aging 10, 919-930. 2015


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Examples of meds available in Ireland :

  • Macrogols 

    • e.g. Movicol, Macrolief, Molaxole

  • Stimulant laxative (as addition or alternative to macrogol)

    • e.g. Senokot

  • Osmotic laxative such as docusate or lactulose if stools are hard

    • e.g. lactulose (Duphalac, )

  • Enemas

    • e.g. Microlax or Micolette (pre and post op or before rectal examination)

  • Suppositories

    • e.g. Glycerine Suppository


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