Constipation Flashcards
What is the general definition of constipation?
Passage of =2 bowel movements/week, with a sense of straining, pain or incomplete evacuation
What might constipation + rectal bleeding indicate?
Cancer
What might constipation + distention + active bowel sounds indicate?
Stricture/obstruction
What might constipation + menorrhagia indicate?
Hypothyroidism
What would you consider asking someone who was presenting with constipation?
- Frequency/nature/constistency?
- Recent change?
- Blood/mucus?
- Diarrhoea as well as constipation?
- Digitating rectum/vagina to pass stool?
- Diet
- Drugs
What is essential to do when examining someone with constipation?
PR exam
What anorectal disease can cause constipation?
- Anal/colorectal cancer
- Fissures
- Rectal prolapse
- Proctalgia fugax
- Mucosal ulceration
- Pelvic muscle/levator ani dysfunction
What are causes of intestinal obstruction which can cause constipation?
- Colorectal cancer
- Strictures
- Pelvic mass
- Diverticulosis
- Pseudo-obstruction
What are metabolic/endocrine causes of constipation?
- Hypercalcaemia
- Hypothyroidism
- Hypokalaemia
- Porphyria
- Lead poisoning
What drugs can cause constipation?
- Opiates
- Anticholinergics
- Iron
- Antacids
- Diuretics
- CCBs
What neuromuscular problems can cause constipation?
- Spinal/nerve injury
- Systemic sclerosis
- Diabetic neuropathy
- Hirschsprung’s disease
- Chagas disease
What are general causes of constipation?
- Poor diet +/- lack of exercise
- Dehydration
- IBS
- Old age
- Post-operative pain
What investigations might you perform in someone with constipation?
None in those who are young - consider investigating if red flag symptoms:
- Bloods - FBC, ESR, U+E’s, Ca2+, TFTs
- Other - Colonoscopy + biopsy
What lifestyle advice would you give someone with constipation?
Reassurance
- Drink more
- Exercise more
- High-fibre diet
What medications can be used to aid constipation?
- Bulking agents
- Stimulant laxatives
- Stool softeners
- Osmotic laxatives
What are bulking agents?
Bulk forming laxatives consist of indigestible polysaccharides which increase faecal mass. This in turn stimulates the stretch receptors in the bowel mucosa which increases peristalsis and defaecation.
What conditions are bulk forming laxatives most useful in?
- IBS
- Diverticulitis
- Those with colostomies/ileostomies
What are examples of bulk forming agents?
- Dietary fibre
- Wheat bran
- Methylcellulose
- Mucilaginous gums – sterculia
- Mucilaginous seeds and seed coats, e.g. ispaghula husk
- Normacol
How do stool softeners work?
Soften the stools making them easier to pass. Arachis oil is a mixture of peanut and ground-nut oil. It is given as an enema in patients with faecal impaction. It works in two ways. It softens the stool and acts as a lubricant.
What conditions are stool softeners most commonly used in?
Managing painful anal conditions e.g. fissures, haemorrhoids
What are examples of osmotic laxatives?
- KleanPrep
- Movicol
- Sodium Picosulphate (Picolax)
- Lactulose
- Phosphate enema
How do osmotic laxatives work?
Increase the amount of water in the large bowel, either by drawing fluid from the body into the bowel or by retaining the fluid they were administered with due to osmotic gradient created by the drug
Why is lactulose useful in hepatic encephalopathy?
Produces low faecal pH, that discourages ammonium producing bacteria from growing
When are phosphate enemas used?
Rapid bowel evacuation prior to procedures
How do stimulant laxatives work?
Increase intestinal motility - speculated that they both act as osmotic laxative and stimulate myenteric plexus
When would you not use stimulant laxatives in someone with contipation?
If it was caused by intestinal obstruction or acute colitis
What can occur if you use stimulant laxatives for prolonged periods?
Colonic atony
What are examples of stimulant laxatives?
- Phenolphthalein
- Bisacodyl
- Anthraquinones – senna and dantron (only for the terminally ill)
- Docusate sodium
- Methylnaltrexone (for opioid induced constipation)
- Lubiprostone
- Prucalopride
- Linaclotide
- Sodium picosulfate
How would you manage constipation?
- Lifestyle advice
- Consider medications/evacuation measures
- Treat cause
What enemas are used in those with constipation?
- Arachis oil
- Docusate sodium
- Hypertonic phosphate
- Sodium citrate
