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 ml of dimethicone emulsion (1 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.