October 22, 2014 — The article by M’Zail et al. (2014) entitled, “Persistence of Microbial Contamination on Transvaginal Ultrasound Probes despite Low-Level Disinfection Procedure” places important and timely focus on a risk of infection that is often overlooked.

The abstract of M’Zail et al.’s (2014) article is provided, below, in Box A, and a copy of the complete article can be downloaded (at no cost) by clicking here.

In short, these authors conclude that improper reprocessing of transvaginal ultrasound probes probes poses a “risk of cross contamination between patients during ultrasound examination.”

Similarly, Benet et al. (2014) — who authored another recently published article entitled “Risk of Human Immunodeficiency Virus and Hepatitis C Virus Infection Related to Endocavitary Ultrasound Probe Exposure in France” (click here) — would seemingly agree with M’Zail et al.’s (2014) findings, also expressing concern about the risk of disease transmission associated with contaminated ultrasound probes.


In addition to M’Zail et al.’s (2014) and Benet et al. (2014), among others, Dr. Muscarella has previously questioned the increased risk of disease transmissions due to the improper disinfection of contaminated transvaginal ultrasound probes.

Others, like the Veterans Health Administration (VHA), however, may not necessarily agree, having concluded that, although inspections of at least one U.S. medical facility confirmed its failure to high-level disinfect transvaginal ultrasound transducers (among other infection-control breaches), the risk of infection to affected patients posed by this breach was deemed to be “negligible” (click here to read the VHA’s risk assessment).

As a result of this assessment, the VHA did not inform patients potentially exposed to such infectious agents as the human papilloma virus (HPV), HIV and the hepatitis B and C viruses of the potential for disease transmission.

Further, similar breaches posing an increased risk of transmission of HPV and other infectious agents have also been recently documented — read the August, 2013, news report: “Infection risk at New Brunswick hospital affects nearly 2,500 women: Colposcopy clinic didn’t always follow sterilization rules for biopsy forceps over 14 years” (click here).


The following recommendations are provided to healthcare professionals:

1.  Review the two aforementioned articles by M’Zail et al.’s (2014) and Benet et al. (2014).

2. Place enhanced focus and attention on the increased risk of disease transmission associated with contaminated transvaginal ultrasound probes and similar types of medical instruments.

Dr. Muscarella’s related articles

A review of the following related articles by Dr. Muscarella is also recommended:

  1. Potentially Faulty Assessment by the Veterans Health Administration of the Risk of Infection Associated with a Number of Confirmed Breaches – click here.
  2. A Tale of Two Assessments of the Risk of Disease Transmission – click here.
  3. The Reprocessing of Sheathed “ENT” Endoscopes, Cystoscopes and Other Types of Flexible Endoscopes – click here.
  4. The Trophon EPR Ultrasound Transducer High-Level Disinfection System: A Few Remarks – click here.

Box A: Abstract of the M’Zail et al. (2014) study

Aim of the Study

In many countries, Low Level Disinfection (LLD) of covered transvaginal ultrasound probes is recommended between patients’ examinations. The aim of this study was to evaluate the antimicrobial efficacy of LLD under routine conditions on a range of microorganisms.

Materials and Methods

Samples were taken over a six month period in a private French Radiology Center. 300 specimens derived from endovaginal ultrasound probes were analyzed after disinfection of the probe with wipes impregnated with a quaternary ammonium compound and chlorhexidine. Human papillomavirus (HPV) was sought in the first set of s100 samples, Chlamydia trachomatis and mycoplasmas were searched in the second set of 100 samples, bacteria and fungi in the third 100 set samples. HPV, C. trachomatis and mycoplasmas were detected by PCR amplification. PCR positive samples were subjected to a nuclease treatment before an additional PCR assay to assess the likely viable microorganisms. Bacteria and fungi were investigated by conventional methods.


A substantial persistence of microorganisms was observed on the disinfected probes: HPV DNA was found on 13% of the samples and 7% in nuclease-resistant form. C. trachomatis DNA was detected on 20% of the probes by primary PCR but only 2% after nuclease treatment, while mycoplasma DNA was amplified in 8% and 4%, respectively. Commensal and/or environmental bacterial flora was present on 86% of the probes, occasionally in mixed culture, and at various levels (10->3000 CFU/probe); Staphylococcus aureus was cultured from 4% of the probes (10-560 CFU/probe). No fungi were isolated.


Our findings raise concerns about the efficacy of impregnated towels as a sole mean for disinfection of ultrasound probes. Although the ultrasound probes are used with disposable covers, our results highlight the potential risk of cross contamination between patients during ultrasound examination and emphasize the need for reviewing the disinfection procedure.

Article by Lawrence Muscarella. Originally posted on October 22, 2014. Updated August 11, 2016, Rev A. © LFM Healthcare Solutions, LLC. All right reserved.

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