Microscopic Topography of Ultrasound Probes: Implications for High-Level Disinfection and Infection Control

Ultrasound probes, which are used routinely in clinical practice, can become contaminated after use. If not effectively processed, they may pose an infection control challenge. Understanding the extent to which microscopic surface topography of ultrasound probes may shield microorganisms is crucial, yet these features remain poorly characterized. This descriptive study used scanning electron microscopy (SEM) to investigate the microscopic topography of ultrasound probe surfaces. Characteristics such as grooves, notches, guide features, orientation markers, and seams were identified on endocavitary (n = 4) and surface (n = 1) probes. Gaps and crevices within these characteristics were assessed for their potential to harbor microorganisms. A total of 46 sites across 15 segments from the five ultrasound probes were examined using a tungsten-filament SEM under low vacuum at an accelerating voltage of 20 kV. Of the 46 sites imaged, 32 showed measurable gaps or crevices, with widths of 0.9 to 480.4 μm. The lens surface revealed microscopically rough texture with crevices as wide as 4.8 μm. Surface wear, such as a displacement scratch on an endocavitary probe shaft, had crevices large enough to shield pathogens. On probe shafts and handles, seam widths of 7.9 to 480.4 μm containing dried residue with gaps were observed. These gaps and crevices are large enough to harbor microorganisms and could be relevant when considering disinfection efficacy. These observations highlighted the relevance of probe surface microtopography as a consideration for future device processing research. Additional studies are needed to determine how cleaning and high-level disinfection processes interact with microscopic surface features across different ultrasound probe designs.