Synopsis
Prescribe bowel cleansing as active treatment by excluding mechanical and inflammatory contraindications, assessing renal, electrolyte and medicine risks, and giving the exact licensed product schedule with verification.
- Exclude obstruction, ileus, perforation, toxic megacolon and severe acute colitis before bowel cleansing.
- Assess hydration, renal function, electrolytes, frailty, swallowing and heart failure risk before prescribing.
- Review diuretics, renin-angiotensin blockers, NSAIDs, lithium, diabetes medicines and antithrombotics individually.
Key red flags
Do not administer oral bowel preparation to a patient with suspected obstruction, ileus, perforation, toxic megacolon or severe colitis; acute pain, distension, vomiting or collapse during preparation needs urgent review.
Reasoning priorities
exclude obstruction, perforation, ileus, toxic megacolon and severe acute inflammatory disease
Symptoms and recent imaging should be reviewed before prescribing; proceeding despite a suspected mechanical problem can worsen distension or perforation.
Worked reasoning
A frail adult booked for morning colonoscopy takes furosemide for ankle oedema and ramipril for hypertension, has stage 3 chronic kidney disease, postural dizziness, sodium 132 mmol/L and creatinine increased from 120 to 168 micromol/L after poor intake.
- Defer bowel preparation and colonoscopy because the patient is clinically volume depleted with acute kidney injury and hyponatraemia; arrange medical assessment and correction rather than issuing a kit.
- After rehydration, repeat observations, sodium and creatinine. Two days later dizziness has resolved, sodium is 137 mmol/L and creatinine has returned to 124 micromol/L.
- Confirm no obstruction, ileus, perforation, toxic megacolon or severe acute colitis, then prescribe the exact Moviprep A/B sachet two-litre course and at least one additional litre of permitted clear liquid.
- Omit ramipril and furosemide on the preparation day. Plan the ramipril review no earlier than 72 hours after the procedure; decide furosemide separately from volume status and its indication rather than giving both medicines one automatic restart time.
- At the 72-hour review the patient is eating and drinking, blood pressure is 132/76 mmHg, sodium 138 mmol/L and creatinine 122 micromol/L, so ramipril is restarted. The patient remains euvolaemic without congestion, so furosemide stays withheld pending the documented prescriber review.