Crystallization in the waterjet channel in colonoscopes due to simethicone.

Colonoscopy is the preferred diagnostic and therapeutic modality in the lower intestinal tract. Most Dutch hospitals use Lefax (Bayer Vital GmbH, Leverkusen, Germany) to optimize endoscopic imaging. The main component of Lefax is simethicone (●" Fig.1), a silicondioxide crystalloid of the silicone polymer dimethicone, which decreases the surface tension of bubbles. Lefax is added towater and injected via the waterjet channel of the colonoscope to create a powerful and directional beam. Recently, a waterjet channel connector (●" Fig.2) broke off a colonoscope (Fujinon EC-590 WL; Fujifilm Corporation, Tokyo, Japan) in our department. During repair, crystalline deposits were noticed inside the connector (●" Fig.3). Closer examination revealed deposits in every component within the channel (●" Fig.4). Infrared spectral analysis by our clinical pharmacy laboratory showed that the crystals consisted of dimethicone (●" Fig.5a,b). A total of 16 colonoscopies are used in our department. All of them are Fujinon scopes, from the series EC-530 WI-H (n= 1), EC-590 WL (n=3), EC-590 WL4 (n=3), and EC-600 WL (n=9), and all had crystal deposits. Crystals could only be seen by thorough inspection, not during regular checkups. Elimination of the crystals was only possible by mechanical cleaning after the connector had been removed and the channel opened. Repeated attempts at washing with (warm) water, peracetic acid, and precleaning detergent (Neodisher SC; Dr Weigert, Mühlenhagen, Hamburg, Germany) were unsuccessful. As the connecFig.2 The colonoscope waterjet connector where crystal deposits were observed.