The Clinician's Third Hand

The Contaminated Stethoscope

Over the past 30 years, as it relates to Healthcare Acquired Infection (HAI) and stethoscope contamination, the medical literature has consistently reported high stethoscope contamination rates, ranging between 30% and 100%.

A 2014 study conducted by the Mayo Proceedings¹ confirmed that the stethoscope diaphragm (the point of contact with the patient) has the same rate of contamination, and highly virulent bacteria, as a clinician’s dominant hand. As noted in the authors discussion, “…considering that stethoscopes are used repeatedly over the course of a day, come directly into contact with patients’ skin, and may harbor several thousands of bacteria (including MRSA) collected during a previous physical examination, we consider them as potentially significant vectors of transmission. Thus, failing to disinfect stethoscopes could constitute a serious patient safety issue akin to omitting hand hygiene. Hence, from infection control and patient safety perspectives, the stethoscope should be regarded as an extension of the physician’s hands.”

Both the hands and the stethoscope are cornerstones of patient evaluation, and are applied patient to patient, collecting and transferring bacteria and contaminants as they move about their patient schedules. Yet while we have invested heavily in initiatives, guidelines and regulations to improve infection control and hand hygiene, the stethoscope has escaped scrutiny and has been simply grouped into a class with bedpans and countertops as “non-critical items”. Due to its frequent importance in examination and rate of contamination, the author suggests that we should think of the stethoscope as the clinician’s “third hand”. From this perspective, we should regard stethoscope contamination with the same priority as that of the clinician’s hands.

The Current Standards for Stethoscope Hygiene​

The Healthcare Infection Control Practices Advisory Committee (HICPAC), a federal advisory committee that advises and guides DHHS and CDC regarding infection control strategies for surveillance, prevention, and control of healthcare-associated infections and antimicrobial resistance across U.S. healthcare settings, recommends “at minimum, noncritical patient-care devices are disinfected when visibly soiled and on a regular basis” (such as after use on each patient or once daily or once weekly).

Stethoscopes are critical component of patient evaluation, and used from patient to patient, collecting and transferring contaminants. As evident from the ambiguity of the recommendation, there is no consensus regarding the frequency of cleaning that is most efficacious. Ironically, while the stethoscope and hands have the same contamination rates and transference process, hand hygiene in the clinical setting is the focus of extensive guidelines, educational campaigns and regulatory compliance initiatives for hygiene compliance prior to every patient interface.²

The recommended method of cleaning stethoscope includes the use of 70 percent alcohol based cleaning products and yields negligible rates of compliance, even after educational intervention.³ The stethoscope cleaning process is impractical for many reasons that have been well characterized.⁴ Furthermore, emerging studies reinforce that alcohol based agents have given way to resistant strains of bacteria over the years.⁵ Reviews of the published literature have appropriately called for new strategies to alter physicians’ recognition and behavior for stethoscope disinfection.⁶

1. Longtin et al, Mayo Proceedings, March 2014: 89(3):291-299
3. Halleck et al. / American Journal of Infection Control 45 (2017) 811-2
4. Muniz et al / American Journal of Infection Control, 2012 1-4
5. Pidot et al., Sci. Transl. Med. 10, eaar6115 1 August 2018
6. Yu, Current Emergency and Hospital Medicine Reports