10.1 Constipation, Bowel Assessment & the Bristol Stool Chart

Constipation, Bowel Assessment & the Bristol Stool Chart

RCSI's Gastrointestinal reading group names the Bristol Stool Chart, constipation, colonoscopy, gastroscopy, H. pylori and coffee-ground vomiting. Constipation appears again as a teaching the junior student nurse example paired with colonoscopy, and management of constipation in palliative care appears under death and dying via NCEC National Clinical Guideline No. 10.

Constipation is easy to dismiss and expensive to miss. In hospital it causes distress, delirium, urinary retention, abdominal pain, nausea and delayed discharge, and at its extreme it causes impaction, overflow, obstruction and perforation.

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Defining Constipation

Constipation is not simply an absence of a daily bowel motion. It is a reduction in a person's usual frequency of defaecation together with difficulty passing stool, and it may include:

• straining on more than a quarter of occasions
• hard or lumpy stool
• a sensation of incomplete evacuation or of anorectal blockage
• needing manual manoeuvres to assist evacuation
• fewer than three spontaneous bowel motions per week

Baseline matters. A person who normally opens their bowels every third day is not constipated on day two. A person who normally goes twice a day and has not been for three days is.

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The Bristol Stool Chart

The Bristol Stool Chart provides shared, objective language for something patients find awkward to describe.

Use it in practice: record the type number on the bowel chart rather than "BO" or "large". "Type 1 x 1, with straining" is clinical data; "bowels open" is not. Types 6 and 7 in a hospital patient should also prompt thought about Clostridioides difficile, particularly after antibiotics - and a stool sample takes the shape of the container, which is the classic descriptor.

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Assessment

A structured bowel assessment covers:

1. Usual pattern - frequency, time of day, stool type, any laxatives normally taken.
2. Current pattern - date and type of last bowel motion, straining, pain, incomplete evacuation, blood or mucus.
3. Associated symptoms - abdominal pain, distension, nausea, vomiting, appetite, weight change, urinary symptoms.
4. Contributing factors - fluid and fibre intake, mobility, new medicines, privacy and access to a toilet, pain on movement.
5. Examination - abdominal inspection for distension, palpation for masses or tenderness, and listening for bowel sounds. A digital rectal examination may be indicated to confirm impaction, but only with valid consent, appropriate training and as permitted by local policy.
6. Documentation - a bowel chart recording date, Bristol type and any intervention.

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Why Hospitalised and Older Patients Become Constipated

Note how many are nursing-modifiable: privacy, position, mobilisation, fluids and timing are all within the nurse's control.

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Faecal Impaction and Overflow

The trap. A patient who has not opened their bowels for a week and now has frequent, small, offensive liquid stools is very unlikely to have simple diarrhoea. This is overflow - liquid stool tracking around a hard, impacted mass. Antidiarrhoeal medication would be actively harmful.

Features of impaction: prolonged absence of a normal motion, abdominal distension and discomfort, palpable faecal loading, liquid leakage or faecal incontinence, new urinary retention or urinary incontinence from pressure, nausea, anorexia and - in older patients - new delirium. Management is medical and local-policy driven, generally combining rectal measures to clear the rectum with oral laxatives to clear higher loading, and then a maintenance plan so it does not recur.

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Management: Do the Simple Things First

Step 1 - Non-pharmacological.

• Fluids: aim for adequate oral intake unless restricted, and record it on a fluid chart.
• Fibre: gradually increase dietary fibre where appropriate. Increasing fibre without increasing fluid makes constipation worse, and fibre is inappropriate in suspected obstruction or in a frail patient with poor intake.
• Mobility: get the patient up. This is where Get Up, Get Dressed, Get Moving directly intersects with bowel care.
• Position: sit on a toilet or commode rather than using a bedpan. Knees higher than hips, feet supported on a footstool, leaning forward with elbows on knees - this straightens the anorectal angle and is far more effective than any leaflet.
• Timing and privacy: use the gastrocolic reflex by offering toileting 20-30 minutes after a meal, and give the person genuine privacy and unhurried time.
• Pain control: a patient who cannot strain because of a painful wound will not defaecate.

Step 2 - Laxatives, by class.

Opioid-induced constipation is predictable and should be pre-empted. Anyone commenced on a regular opioid needs a stimulant laxative prescribed at the same time, usually with a softener. Bulk-forming laxatives are the wrong choice here: opioids slow transit, and adding bulk to a slow bowel risks impaction.

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Red Flags

Escalate urgently if any of the following are present:

• a change in bowel habit lasting more than three weeks, particularly over the age of 50
• rectal bleeding or blood mixed through the stool
• unexplained weight loss
• iron-deficiency anaemia without an obvious cause
• a palpable abdominal or rectal mass
• absolute constipation (no stool and no flatus) with vomiting, distension and pain, which suggests obstruction
• new-onset severe constipation in an older person with no obvious cause

These are the symptoms that lead to colonoscopy, which is why RCSI pairs constipation with colonoscopy in its teaching-station examples.

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Teaching a Student About Colonoscopy

Colonoscopy is endoscopic examination of the whole colon, allowing biopsy and polyp removal. The points a junior student needs:

• Consent must be valid: the person understands the procedure, its benefits, and its risks - principally bleeding, infection and the small risk of perforation.
• Bowel preparation is the part patients find hardest. A low-residue diet is followed by an oral preparation and clear fluids. Explain plainly that the preparation causes profuse diarrhoea, that easy toilet access is essential, and that incomplete preparation means an incomplete examination and a repeat procedure.
• Medication review: anticoagulants, antiplatelets, iron and sometimes diabetic medication need specific instructions. Iron discolours the bowel and obscures the view.
• Hydration: the preparation causes substantial fluid loss; older patients and those on diuretics or ACE inhibitors are at risk of dehydration and acute kidney injury.
• Sedation means the patient cannot drive, operate machinery, sign legal documents or be left alone for the rest of the day, and needs a responsible adult to accompany them home.
• After the procedure: monitor observations, expect some bloating and wind from insufflated air, and give clear written advice about when to seek help - severe abdominal pain, significant bleeding, fever or dizziness.