Resistance of conformable indwelling urinary catheters to encrustation.

Conformable and conventional indwelling urinary catheters, made of latex coated with Teflon and of the same nominal size, were encrusted in vitro. The extent of encrustation was quantified by dissolving the deposits, determining the concentrations of calcium and magnesium in the resulting solutions (by atomic adsorption spectroscopy), and calculating the surface densities of calcium and magnesium. Surface densities of both elements were significantly less on the conformable than on the conventional catheters. This result can be explained by the pulsed flow of urine through the conformable catheter tending to dislodge deposits adhering to its inner surface. A similar action is expected to occur in vivo.