Achieving quality in colonoscopy: bowel preparation timing and colon cleanliness

Colonoscopy is considered the gold standard for investigation of large bowel pathology. Numerous factors influence the efficacy of bowel preparation for colonoscopy. Inadequate bowel preparation can lead to missed pathology. Timing of fasting and bowel preparation, timing of procedure and possibly patient bowel habit and presence of diverticula may have an influence on the quality of the preparation. The aim of this study was to investigate the quality of cleansing of sodium picosulfate (Picoprep-3™, Pharmatel Fresenius Kabi Pty Ltd, Pymble, NSW, Australia) with different administration schedules and to evaluate whether patient's bowel patterns influence the quality of cleansing.

Three hundred twenty-five patients (175 morning and 150 afternoon procedures) were interviewed prior to colonoscopy to evaluate bowel habit and timing of preparation administration. Quality of cleansing was then assessed during colonoscopy using a 5-point scale. Further factors analysed included the patient's prior bowel habit and the presence of diverticula at colonoscopy. Procedural end points evaluated included procedure total time, caecal intubation time and withdrawal times.

The quality of cleansing for individual bowel segments was worse for afternoon procedures (P < 0.05 for some segments) and for patients with prior constipation (P < 0.05 for descending colon segments). Caecal intubation times were shorter for patients with diarrhoea and longer for female patients, who also had shorter withdrawal times. No correlation was found between the procedural end points (total duration, caecal intubation time and withdrawal times) and the timing of fasting.

Quality of cleansing is significantly improved when bowel preparation is taken entirely the day prior to colonoscopy. Patients with prior constipation demonstrated poorer cleansing.