Improved quality of anorectal endoluminal ultrasonography using emulsion of dimethicone

PURPOSE: This study was designed to show the benefits of filling echography probes with water mixed with dimethicone to preclude artifacts caused by bubbles. METHODS: One hundred consecutive healthy volunteers (42 males; mean age, 46 years; range, 17-72 years) were blindly randomized to undergo rectal ultrasonography using conventional degassed water or degassed aqueous solution made of 40 ml of water and 10 nil of dimethicone emulsion (I ml/100 mg). All examinations performed by the same surgeon-unaware of nature of filler liquid-for ten minutes, and number of rectal ultrasonographies with artifacts attributable to air bubbles was recorded. RESULTS: Endoluminal ultrasonography performed with conventional degassed water presented artifacts attributed to presence of air bubbles in 30 of 50 examinations (60 percent). When degassed aqueous solution was used, only 5 of 50 examinations showed artifacts caused by presence of air bubbles (10 percent). This difference was statistically significant (P < 0.0005). The use of conventional fluid was associated with artifacts secondary to the presence of air bubbles, adjusted odds ratio 13.5 (95 percent confidence interval, 4.56-39.88). During this experience, the solution did not damage ultrasound scanner. CONCLUSIONS: We found that use of a dimethicone-degassed water mixture is simple, not expensive, safe, effective, and may reduce frequency of sonographic distortion in presence of air bubbles.