15.2 Infection Control, Disinfection & Sterile Technique

Match precautions and reprocessing to the actual contact

Vascular examinations involve intact skin, wounds, devices, and sometimes ultrasound-guided procedures. Standard precautions apply to every patient. Add transmission-based precautions when indicated and follow the facility's infection-prevention policy. A probe cover is a barrier, not a substitute for cleaning and the required reprocessing between patients.

Before scanning, identify the expected contact, choose appropriate PPE, inspect the probe, and prepare the required gel and cover. Keep clean and contaminated equipment separate. During bedside work, protect the console, keyboard, cable, cuffs, and other surfaces that may be touched with contaminated gloves. Cleaning only the probe face leaves other transmission opportunities unaddressed.

Hand hygiene and PPE

Perform hand hygiene at the appropriate points before and after patient contact, before aseptic tasks, after contamination risk, and after glove removal. Alcohol-based hand rub is preferred for most routine healthcare situations when hands are not visibly soiled. Use soap and water for visibly soiled hands and the specific situations required by infection-prevention guidance.

Alcohol does not kill C. difficile spores. CDC encourages soap-and-water washing after care during C. difficile outbreaks as an additional precaution, with appropriate glove use and contact precautions. Follow the facility's policy, which may be more specific. Norovirus is a virus, not a spore-forming organism; do not explain its hand-hygiene requirements by calling it a spore former.

Use gloves when contact with blood, body fluids, mucosa, nonintact skin, or contaminated equipment is anticipated. Change them between patients and when moving from a contaminated task to a clean task. Gloves do not replace hand hygiene. Choose gowns, masks, eye protection, and respiratory protection according to exposure and the applicable transmission precautions rather than one fixed outfit for every patient.

Spaulding classification

The Spaulding framework classifies a device by its intended contact, not by its price or whether it is called an ultrasound probe.

An ordinary external vascular probe used only on intact skin is noncritical. A device directly contacting an open wound or mucosa enters a different risk category. A needle entering a vessel is critical. The probe outside intact skin during a percutaneous procedure must be distinguished from the needle that enters the patient.

Current percutaneous-procedure guidance

AIUM's 2025 revision describes low-level cleaning/disinfection with an appropriate single-use cover for external transducers used in percutaneous needle/catheter placement. The required sterility of the cover depends on the procedure. A clean peripheral IV placement and a fully sterile biopsy or central-access procedure do not necessarily use identical barriers. Follow the procedure-specific policy and device instructions, and escalate reprocessing when actual contamination or contact requires it.

For mucosal or direct nonintact-skin contact, apply the relevant semicritical requirements. Do not teach that every covered external vascular-access probe automatically requires HLD, or that a cover permits ignoring cleaning after use. If a cover tears or blood/body fluid contamination occurs, follow the validated contamination response and compatible reprocessing instructions.

Cleaning comes first

Remove gel and visible material promptly and clean with the method compatible with the device. Organic soil can interfere with disinfection. Reprocessing agents, detergent choice, immersion depth, temperature, exposure time, rinsing, drying, and storage must follow the manufacturer's instructions for use (IFU) and the validated process. An unsourced universal chemical concentration or cycle time is unsafe because different products and systems have different requirements.

For reusable chemical baths, verify effectiveness and replacement requirements as specified by the product. For automated systems, complete the required cycle checks and documentation. Keep records according to the facility's quality process. A failed cycle is not a completed disinfection; follow the failure procedure before the device returns to use.

Inspect the lens, housing, cable, insulation, and connector. Cracks or damage can impair imaging and make safe cleaning difficult. Remove damaged equipment from service through the defined process. Do not immerse connectors or cable portions beyond the IFU limits simply because the probe head tolerates immersion.

Heat compatibility and the Curie-point misconception

Routine diagnostic probes generally cannot undergo ordinary steam autoclaving unless specifically designed and validated for it. Heat can damage adhesives, lenses, insulation, and electronics well below the Curie temperature of a typical PZT element. Standard autoclave temperatures around 121–134°C do not exceed a typical PZT Curie point around 300°C or higher. Curie-point depolarization is therefore not the correct explanation for ordinary steam damage.

Choose a validated compatible reprocessing method, not an improvised heat or chemical treatment. Some devices have specialized sterilization compatibility; the device-specific IFU governs. Avoid absolute claims that all ultrasound transducers share the same material properties and allowable process.

Gel and aseptic technique

Use single-use sterile gel when sterility is required, for invasive procedures as specified, and for relevant nonintact-skin situations. Prepare an appropriate cover without contaminating its patient-contact surface and avoid trapped air that causes image dropout. Keep the sterile field and cable management appropriate to the procedure. Do not refill single-use containers or treat a warmed multi-use bottle as sterile.

Worked examination choices

For routine carotid duplex on intact skin, clean and disinfect the external probe with the compatible noncritical process between patients. For direct contact with an open ulcer, use the required barrier and semicritical reprocessing framework. For ultrasound-guided vascular access with an external probe remaining over prepared intact skin, apply the current procedure-specific cover and reprocessing guidance, distinguishing probe contact from the critical needle.

These choices require recognizing actual contact and following current instructions. The examination name alone does not decide the entire infection-prevention process.

AIUM 2025 transducer/gel guidance, CDC disinfection recommendations, and CDC clinical hand hygiene — checked October 18, 2026.