Oral bowel cleansing agents are used before endoscopic and radiological assessment of large and small intestine to minimise faecal contamination. In general these are safe and well tolerated. When administered correctly bowel preparation have been demonstrated to be safe for use in healthy individuals without significant co-morbidity, and to effect adequate cleansing. Current practice for elective procedures is typically for patients to self medicate oral bowel cleansing agents at home. A screening process is necessary to ensure that patients at risk of harm from oral bowel cleansing are identified and prepared appropriately.
Klean Prep: polyethylene glycol
Klean Prep is generally safer than other bowel preparation for patients with renal impairment, electrolyte or fluid imbalances.
1. Oral tagging and bowel preparation with Pico prep: sodium picosulphate and magnesium citrate
Pico prep should be used in caution in patients at risk or suffering from hypovolaemia, including those patients taking high dose diuretics, those with congestive cardiac failure and advanced cirrhosis and those with chronic kidney disease. Relative contraindication in stage 4 and 5 chronic kidney disease (GFR <30 or on dialysis)
If no recent measurement of kidney function is available (within 3 months), kidney function should be measured (using estimated creatinine concentration) in patients with known
2. No bowel preparation with oral tagging agent only
If there is co-morbidity that may increase the risk of complications from bowel preparation, it is worth considering CT colonography with faecal tagging only without bowel preparation. This is an effective method of diagnosing and excluding colon cancer although has limited role in diagnosing polyps.
At risk for hypovolaemia
Admission for intravenous fluid replacement should be considered in all patients who may be unable to maintain adequate oral intake at home( for example, the elderly and those with reduced mobility). Patients at risk for hypovolaemia include (but not limited to) those with chronic or severe diarrhoea, chronic vomiting, dysphagia, those with persistent hyperglycaemia and those taking high dose diuretics.
Caution is advised in the administration of oral bowel cleansing preparations to patients taking certain medications.
Angiotensin Converting enzyme inhibitors and angiotensin ll receptor blockers
Prone to deterioration in renal function during periods of hypovolaemia. Where possible renin angio blockers should be discontinued on the day of administration of oral bowel cleansing agents and not reinstated until 72 hours after the procedure.
Diuretics may alter electrolyte imbalance and predispose to intravascular volume depletion especially in high doses. Unless there is judged to be a significant risk of pulmonary oedema, diuretics should be temporarily discontinued on the day of oral bowel cleansing preparation
Non-steroidal Anti-inflammatory Drugs (NSAID's)
These medications reduce renal perfusion and therefore limit the kidneys capacity to compensate for reduced renal perfusion through volume depletion. NSAIDs should be discontinued on the day of administration of oral bowel cleansing preparations and with-held until 72 hours after the procedure.
Medications known to induce the syndrome of inappropriate anti diuretic hormone (SIADH) secretion
Increase the risk of water retention and or electrolyte imbalance and include tricyclic antidepressants, selective serotonin reuptake inhibitors, many anti-psychotic drugs and carbamazepine. Whilst these need not be discontinued, serum U&E should be checked prior to administration of bowel preparation.
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