Review
Infectious risk of endovaginal and transrectal ultrasonography: systematic review and meta-analysis

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Summary

Background

Appropriate endovaginal/rectal ultrasound transducer disinfection has been an ongoing and vexed question in gynaecology, obstetrics and urology. However, the routine use of probe covers followed by low-level disinfection (wipes/spray) is usually applied between patients in some countries (e.g. France).

Aim

To perform a systematic review and meta-analysis of the scientific literature in order to identify case reports of contamination following endovaginal/rectal probe use, and to estimate the infection prevalence related to the use of these probes in common daily practice.

Methods

Systematic review and meta-analysis.

Results

From the 867 potentially eligible references, 32 articles were finally included. Very few cases with an established route of contamination had been reported. Indeed, apart from occurrence of outbreaks, it is difficult if not impossible to detect viral contamination through the use of endovaginal/rectal ultrasound probes. However, there was a pooled prevalence of 12.9% (95% confidence interval: 1.7–24.3) for pathogenic bacteria, and 1.0% (0.0–10.0) for frequently occurring virus (human papillomavirus, herpes simplex virus, and cytomegalovirus) for endovaginal/rectal probes, both after low-level disinfection. The pooled prevalence of infected patients after transrectal ultrasound and guided biopsies was estimated to be 3.1% (1.6–4.3).

Conclusions

There appears to be a risk of transmitting bacterial or viral infections via endovaginal/rectal ultrasound transducer, and the present meta-analysis provides an estimate of this risk. Further research with sophisticated modelling is warranted to quantify the risk.

Introduction

Appropriate ultrasound transducer disinfection has been an ongoing and vexed question, and hygiene of ultrasound probes continues to be discussed in gynaecology, obstetrics and urology. The cost of transducers precludes a single-use-only strategy. The key infection control issue concerns the risk of contamination and the need for specific cleaning/disinfection procedures to ensure a high degree of protection against infectious disease transmission, even when a disposable cover is used. Endovaginal and transrectal ultrasound are considered as at least medium-risk procedures involving contact with mucous membranes.1, 2, 3 The main pathogens of concern are human immunodeficiency virus (HIV), cytomegalovirus (CMV), human papilloma virus (HPV), enteric Gram-negative pathogens (e.g. Escherichia coli, Klebsiella spp.), for both ultrasound examinations, and C. difficile more specifically for transrectal ultrasound, and gonorrhoea and syphilis for endovaginal ultrasound. Typically, the transducer head is protected with a sheath that can be made of latex, polyurethane, or another substance. Disposal of the cover is followed by cleansing and disinfection using a virucidal agent compatible with the transducer. If it does not damage the probe, the preferred method of disinfection is immersion (in either a low- or high-level disinfectant depending on the country). The most commonly recommended agents – glutaraldehyde, aldehydes and quaternary agents – are used because of transducer surface compatibility rather than the effectiveness of these agents' disinfecting properties. However, glutaraldehyde or other aldehydes are questioned because they may shorten the transducer life and because they can generate adverse events for workers and patients (i.e. chemical damage to the mucosa if the device is insufficiently rinsed), and for procedure (e.g. damage of gametes and embryos in the case of in vitro fertilization). If the probe cannot be immersed, wiping the probe with a disinfectant is the next best choice. Least desirable is applying the disinfectant with a swab, as it corresponds to low-level of disinfection.

The use of condoms as probe covers as means to avoid high-level disinfection is not recommended even though they present a lower rate of perforation compared to commercial probe sheaths. The overall rate of probe cover perforation is 1–9%. Nevertheless, every patient must be regarded as a potential source of infection. Because of the risk of disruption, recommendations in the USA, Canada and Australia insist on high-level disinfection of the probes.1, 2, 3, 4 However, it remains to estimate the infectious risk for the patient, especially as the procedure requires contact with mucous membranes.

We thus aimed to undertake a systematic review and meta-analysis to: (i) summarize the existing evidence of cases of infected patients related to the use of endocavitary ultrasound focusing on endovaginal and transrectal ultrasound; (ii) summarize and calculate a pooled estimate of probe contamination regarding bacteria and virus for endovaginal ultrasound after probe cover and cleaning procedures; and (iii) summarize and provide a pooled prevalence of the number of infected patients after transrectal ultrasound.

Section snippets

Study design

We performed a systematic review and meta-analysis, in accordance with the Center for Reviews and Dissemination guidelines for undertaking systematic reviews and PRISMA guidelines in order to: (i) identify case reports of infectious contamination due to endovaginal probe use; (ii) estimate the infectious risk related to the use of endovaginal probe in usual daily practice; and (iii) estimate the infectious risk related to transrectal ultrasound.5, 6

Literature search

We searched Medline and Embase database for

Characteristics of studies

The electronic search identified 867 references, after having discarded duplicates (Figure 1). Based on the title or abstract, 62 references were considered as potentially eligible. The manual review and the discussion with experts identified eight extra references for a total of 80 potentially eligible articles. After reading the full text, we included four reports of cases or case series of infections related to endovaginal or transrectal ultrasound; four articles on microbial contamination

Discussion

To our knowledge, we performed the first systematic review and meta-analysis on the infectious risk related to endovaginal and transrectal ultrasound. First, we confirmed that very few cases with an established route of contamination had been reported. Indeed, apart from occurrence of outbreaks, it is difficult if not impossible to detect viral contamination through the use of endovaginal/rectal ultrasound probes, because the infections are so numerous (CMV, HSV, HPV); so infrequent (HIV, HBV,

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