Constipation is a symptom which describes when patients have difficulty passing stools, infrequency in emptying the bowels or a feeling of incomplete bowel emptying.
Clinical Features
Constipation can be a subjective term but generally, patients will complain of some of the following symptoms:
- Straining
- Infrequent passage of stool (medical texts may reference <3/week but consider what is normal for the patient).
- Passing hard stools
- Feeling of incomplete emptying of bowel (tenesmus)
Causes
- Low fibre diet/inadequate fluid intake
- Drugs: There are many which can cause constipation including:
- Opioids
- Calcium channel blockers
- Iron supplements
- Malignancy: Some colorectal cancers may present with constipation (or fluctuation between constipation and diarrhoea)
- Hypothyroidism
- Hypercalcaemia
- Bowel obstruction
- Hirschprung’s disease
- Rectocoele
- Paralytic ileus following surgery in particular
- Spinal injuries
- Irritable Bowel Syndrome
Investigations
Constipation is largely a clinical diagnosis but in certain circumstances, investigations may be warranted e.g., long-standing constipation/constipation associated with red flag symptoms such as weight loss, PR bleeding etc.
Bedside
- History: Rule out red flags e.g. absolute constipation (i.e. including flatus for ?bowel obstruction), PR bleeding, weight loss etc.
- Abdominal examination
- PR examination: is hard stool palpable in the rectum? Any masses? Haemorrhoids?
Bloods
- FBC, U&E, LFT, TFT, Calcium, Magnesium: Could electrolyte abnormalities be causing constipation?
Imaging
- AXR/CXR: If concerned about bowel perforation/bowel obstruction
Management
Conservative
NICE CKS guidelines recommend a gradual increase in fibrous intake in order to reduce bloating and flatulence. Adults should be advised to aim for a daily intake of 30g of fibre. Fibrous foods include whole grains, fruits high in sorbitol such as apples/peaches/pears/grapes, and vegetables. They should also ensure adequate hydration with oral fluids.
Medical
Understanding the classes of laxatives will help you to understand which ones are best to use. There are 4 main categories: bulk-forming, stimulant, osmotic, and enemas/suppositories. Try and consider whether or not a laxative is a ‘pusher’ i.e. it stimulates the bowel, or a ‘softener’ i.e. it softens the stool.
- Bulk-Forming Laxatives: These are laxatives which increase the bulk of the stool which stimulates the bowel (may be thought of as a pusher)
- Fybogel also known as isaghula husk
- Methylcellulose
- Stimulant Laxatives: As the name suggests, these directly stimulate the bowel (pusher).
- Senna (or brand name, Senakot)
- Bisacodyl (or brand name, Dulcolax)
- Osmotic Laxatives: These draw water into the bowel to help soften stool (softener).
- Macrogol (or brand name Movicol)
- Lactulose
- Polyethylene Glycol
- Suppositories/Enemas
- Docusate sodium (enema)This is mainly a softener but also has weak stimulant activity
- Glycerol suppository
- Arachis oil enema
- Phosphate enema
For use in hospital, you should consult trust guidelines for management of constipation. However, NICE CKS have also published guidance on managing constipation which is as follows:
Acute/Chronic Constipation
NICE CKS recommend (in addition to conservative measures):
- First line: Bulk-forming laxative
- Second line: Add or switch to osmotic laxative
- Soft stools but hard to pass/incomplete emptying: Add a stimulant laxative.
It is also important to look for, and address, any undderlying causes
Opioid-Induced Constipation
NICE CKS recommend a different regimen. As the underlying pathophysiology is different in this instance, patients should be offered an osmotic laxative and a stimulant laxative (i.e. a softener and a pusher) as first-line as opposed to a bulk-forming laxative.
References
https://www.nhs.uk/conditions/laxatives/
https://cks.nice.org.uk/topics/constipation/management/adults/
