More on Mucus Production by Water Filling During Colonoscope Insertion
Douglas K. Rex, MD, MASGE, reviewing Cheng CL, et al. Clin Transl Gastroenterol 2023 Apr 28.
Water instillation is now commonly used for a variety of purposes during colonoscopy. Water filling during colonoscope insertion has been shown to decrease pain, reduce sedative requirements, facilitate cecal intubation in redundant colons, as well as prevent barotrauma and facilitate sigmoid passage in patients with severe diverticular disease. A previous blinded trial showed that water filling during insertion resulted in excess mucus production in the rectosigmoid during withdrawal, but mucus production did not occur when saline solution was used rather than water.
In a 4-arm randomized trial of 296 patients, rectosigmoid mucus was compared when insertion was performed with water exchange, 25% saline solution, 50% saline solution, or carbon dioxide only. Left-sided colon mucus scores were 1.4, 0.7, 0.5, and 0.2, respectively. Differences between all groups were statistically significant except between the two saline groups. The adenoma detection rate was numerically highest with 50% saline solution (53.9%) and lowest with water exchange (41.3%), but the differences were not significant.
COMMENTThese results confirm that water filling during colonoscope insertion leads to left-sided colon mucus production and suggest this mucus production inhibits polyp detection. Manufacturers have warned that saline instillation could damage the colonoscope working channel. These results indicate the need for more proof regarding whether saline solution truly damages channels.
Many experts who discuss the use of water during colonoscopy are really using saline solution, and this applies to both insertion uses as well as underwater resection. Future studies of water insertion, water exchange, and underwater resection should specify the infused material.
Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.
CITATION(S)
Cheng CL, Kuo YL, Liu NJ, et al. Randomized trial comparing left colon mucus production using water versus saline during water exchange colonoscopy. Clin Transl Gastroenterol 2023 Apr 28. (Epub ahead of print) (https://doi.org/10.14309/ctg.0000000000000594)
