A pilot study of endoluminal US for stool liquefaction

Background There is a need to cleanse patients who are poorly prepared for colonoscopy safely and efficiently during the procedure to minimize rescheduling. US is already being used in catheter-based intravascular thrombolysis, and time-reversal acoustic (TRA) has been explored in assisting drug delivery to the brain. Objective To explore the efficacy and safety of a miniaturized endoluminal US device in stool dissolution as a means to salvage poor bowel preparation. Design Proof of concept experimental study. Settings Animal laboratory. Interventions Low-frequency US and TRAs. Main Outcome Measurements Feasibility, efficacy, and safety of US to liquefy stools ex vivo. Results Depending on parameters, such as pulse rate, acoustic intensity, and duration, increases in liquefaction speeds by a factor of 50 and 100 times were obtained. There was a significant difference in weight change between the 20-kHz–treated sample compared with controls ( P ≤ .0001). There was no difference in sloughing of mucosa and mechanical injury among the US, water spray, and control groups. Limitations Animal model. Conclusion Endoluminal US can liquefy stools at acoustic exposure levels that do not damage ex vivo colonic mucosa. Endoluminal US should be able to dissolve stools more rapidly than water spray alone, thereby optimizing colonoscopic evaluation in vivo.