Constipation Flashcards
Define constipation
Constipation = decrease in the frequency of bowel movements, characterised by the passing of hard stools, which may be large and associated with straining and pain
2 or more of the following features:
* Infrequent passage (<3 complete stools per week)
* Hard, large stool
* “Rabbit dropping” stool
* Overflow soiling
Define chronic constipation and faecal loading
Chronic constipation = constipation that > 3 months
Faecal loading/impaction = retention of faeces to the extent that spontaneous evacuation is unlikely
Aetiology of constipation
Dehydration:
- Inadequate hydration
- Vomiting, hot weather, febrile illness
Inadequate dietary fibre intake
Bowel obstruction
Functional constipation
Hirschprung’s
Medication
Endocrinological: Diabetes, hypercalcaemia/hyperPTH, hypothyroidism, hypermagnesaemia, hypokalaemia, uraemia
Myopathic: amyloidosis, myotonic dystrophy, scleroderma
Neuro: Autonomic neuropathy, CVA, Hirschprung’s, MS, Parkinsons’s, spinal cord injury
Structural: anal fissure, colonic strictures, IBD, mass lesions, rectal prolapse, roectocele postnatal damage
What medications cause constipation
Aluminium-containing antacids, iron supplements, calcium supplements
Opioids, NSAIDs
Procyclidine, oxybutynin (antimuscarinics)
TCAs
Clozapine, quetiapine, amisulpride (Antipsychotics)
Carbamazepine, gabapentin, oxcarbazepine, pregabalin, phenytoin (anti-epilpetics)
Hydroxyzine (antihistamines)
Hyoscine, dicycloverine (antispasmodics)
Verapamil (CCBs)
Furosemide (diuretics)
Symptoms of constipation
“constipation”
- <3 stools a week (unless exclusively breastfed)
- Stools typically semi-soft (3 or 4 on Bristol Stool Form scale)
- Hard, large stool, may block the toilet
- Rabbit droppings-like stool
May present with soiling of the clothes due to overflow from overloaded bowel and stool retention (faecal impaction)
- Loose, smelly stools that are passed without sensation or awareness – may be thick and sticky, or dry and flaky
Difficulty defecating
- Distress or pain on passing stool
- Bleeding associated with hard stool
- Straining
- “Retentive posturing” (straight-legged, tiptoes, with an arched back)
Poor appetite that improves with passage of large stool
Waxing and waning of abdominal pain
Anal pain
Also consider in those with confusion, delirium, urinary retention, or nausea/loss of appetite
Symptoms of faecal loading/impaction
Hard, lumpy stools, which may be large and infrequent (for example passed every 7–10 days), or small and relatively frequent (for example passed every 2–3 days).
Having to use manual methods to extract faeces.
Overflow faecal incontinence, or loose stool.
Signs of constipation on examination
Height and weight
* ?failure to thrive (Hirschsprung’s, hypothyroidism, coeliac)
General
* Signs of precipitant dehydration: sunken eyes, poor skin turgor, dry mucous membranes, prolonged CRT
* “retentitive posturing”: straight-legged, tiptoes, arched back
Abdominal exam
* May show abdominal mass, often LLQ
Anorectal
* May see anal fissures
* May find hard stools
* Assess for signs of sexual abuse
* Perianal streptococcal infection: bright red erythema and local oedema
Idiopathic: normal appearance
Management for constipation
Conservative:
- Diet advice : fruits (white sorbitol), whole grains, vegetables, psyllium + fluids
- Increase activity/exercise
- Toilet routine: regular, unhurried
Medical
Exclude secondary causes + Stop any offending drugs
First line: Bulk-forming laxative e.g. isphaghula (Do NOT prescribe if opioid-induced)
Second line: osmotic laxative e.g. macrogol
Soft stools that are difficult to pass or incomplete emptying: + stimulant laxative e.g. senna
Acute treatment failure = if at least two laxatives from different classes have been tried at the highest tolerated recommended doses for at least 6 months → Prucalopride (prokinetic) for 4 weeks
Management for faecal loading/impaction
First line: oral macrogol
Second line (Or soft stool): Senna (stimulant)
Third line:
- Suppository e.g. bisacodyl, glycerine (both if hard)
- Enema e.g. docusate or sodium citrate
Fourth line: sodium phosphate or arachis oil retention enema (place high in the rectum)
What might be done for those with unremitting constipation
Flexible sigmoidoscopy
Colonoscopy
CT colonography
AXR
Anorectal manometry
Defecation proctogram
Colon transit time studies
Biofeedback training by a physiotherapist (pelvic floor dyssynergia)
Surgery e.g. subtotal colectomy
What are the types of laxative
Bulk-forming (increases faecal mass → stimulates peristalsis): isphaghula husk, fybogel
Osmotic (increases fluid in the large bowel → softens the stool): movicol, lactulose
Stimulant laxative (stimulates the colon): senna, bisacodyl, sodium picosulphate
Softening (lubricates) → docusate sodium, arachis oil, milpar
Complications of laxative use
Macrogol: abdominal pain, bloating, flatulence, nausea and vomiting
Lactulose: nausea (can give with water, fruit, juice, meals), vomiting, flatulence, cramps, bloating
Stimulant laxatives: abdominal cramps, diarrhoea, nausea, vomiting, yellow-brown discolouration of the urine
Complications of constipation
Overflow diarrhoea and soiling (long-standing complications lead to overdistension of the rectum → loss of feeling to need to defecate + inhibition of the internal sphincter
Anal fissures (pain → stool withholding → stool hardening → constipation)
Haemorrhoids
Rectal prolapse
Megarectum/megacolon
Volvulus
Recurrent UTI
Distress
