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Three Part Question

When [transvaginal ultrasound is performed in the emergency department] do [current practices of low-level decontamination and use of probe sheaths] prevent [microbial contamination] ?

Clinical Scenario

A 25 years old woman presents to the ER with a chief complaint of first trimester vaginal bleeding. Her vitals are unremarkable. You perform a transvaginal ultrasonography using a condom on the probe and confirm the presence of an intrauterine pregnancy. Once the exam is completed, you clean the probe. You wonder if probe sheaths and low level decontamination were studied regarding microbial contamination.

Search Strategy

Bestbets
Cochrane
Medline via pubmed (French and English)
Embase
References were reviewed
No best bets found
No Cochrane review found

Medline: 1960/01/01 to 2015/01 /01 via pubmed,

- Filters : French and English
1. Endosonography {MeSH}: 9086
2. Ultrasonography, prenatal {MeSH} : 25696
3. Ultrasonography {MeSH} : 252514
4. Emergency service, Hospital {MeSH} : 50527
5. Cross infection {MeSH} : 47394
6. Equipment contamination {MeSH} : 9989
7. Condom {MeSH} : 7084 no filters
8. Transvaginal ultrasonography : 5849
9. Endovaginal ultrasound: 471
10. Endovaginal ultrasonography: 413
11. Transvaginal ultrasound: 7094
12. Transvaginal ultrasonography : 5849
13. Emergency Medical Service {MeSH} : 97119
14. Endocavitary ultrasound probe contamination : 1
15. Endocavitary ultrasound probe infection : 5
16. Vaginal probe cover : 10
17. 1 + 4 : 8
18. 1+13 : 12
19. 1+5 : 2
20. 1+6: 5
21. 1+7 : 2
22. 1+4+5: 0
23. 1+13+5 : 0
24. 1+13 + 5: 0
25. 1+4+6: 0
26. 1+4+5: 0
27. 1+4+6: 0
28. 2+4 : 38
29. 2+4+5 : 0
30. 2+4+6 : 0
31. 3+5 : 115
32. 3+6 : 85
33. 3+4 : 775
34. 3+4+5 : 5
35. 3+4+6: 7
36. 3+6+7 : 2
37. 4+5+8 : 1
38. 8+7 : 1
39. 8+6: 4
40. 8+7 : 5
41. 9+5: 2
42. 9+6 : 4
43. 9+7 : 1
44. 10+5: 2
45. 10+6:4
46. 10 + 7 : 1
47. 11+5 : 1
48. 11+ 6: 4
49. 11+7:5
50. 12+5 : 1
51. 12+6 : 4
52. 12+7 : 5
53. 7+9 : 1
54. 1+7 : 2
55. 1+6+7 : 0

- Embase : < 1966 to 2015
- Filters :
1. Endosonography: 19157
2. Transvaginal AND ultrasound: 9 049
3. Transvaginal AND ultrasonography : 3 667
4. Endovaginal ANDN ultrasonography: 196
5. Endovaginal ultrasound: 457
6. Emergency department: 1 807
7. Contamination: 183 619
8. Cross AND infection: 83 517
9. Nosocomial AND infection: 27 434
10. Condom: 20 148
11. Endocavitary ultrasound probe infection : 5
12. Endocavitary probe contamination: 1
13. Endocavitary probe hygiene : 2
14. Vaginal probe cover : 11
15. 1+6+7: 0
16. 1+7 : 60
17. 1+6+8 :0
18. 1+6+9: 0
19. 2+6+7: 2
20. 2+7: 27
21. 2+10: 10
22. 2+11: 10
23. 2+6+8:0
24. 2+6+9:0
25. 3+6+7 : 1
26. 3+7 : 8
27. 3+6+8:0
28. 3+6+9:0
29. 3+10: 4
30. 4+6+7: 1
31. 4+6+8:0
32. 4+6+9:0
33. 4+10: 0

Search Outcome

Eight relevant papers were selected out of twenty-two after reading the articles.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Ma S et al 2013 China	1) Surveillance n = 120 2) Serial samples n=76 18 years Less than 12 weeks pregnant Chief complaint of bleeding or abdominal pain	Two independent cross-sectional studies ED conducted	Contamination rates from twice daily swabs for 60 days PCR for DNA detection of HPV	HPV detection (n = 120) 7,5% CI not specified Contamination higher in days 1-20 (20%)	Not blinded Little sample size Coupling gel not analysed No testing for viral load Dry cotton wool swabs stored in normal saline (loss in sensitivity) 3 consecutive swabs on probe might increase contamination by operator manipulations
			Contamination rates (disinfection procedure : condoms removal, dry wipe then T-spray application) PCR for DNA detection of HPV	HPV detection before disinfection : 1 (1,2% CI not specified) HPV detection after disinfection in HPV positive patients on high vaginal swab (n=14): 3
M’Kazil F et a 2014 France	300 Consecutive swabs of vaginal ultrasound probes	Prospective 1 private radiology center	Contamination rate after removal of CE disposable sheaths, sterile dry wipe and disinfection with Prodene wipes PCR DNA detection	HPV (n=100): 13% (95% CI 6-20) Chlamydia trachomatis (n=100) 20% (95% CI 12-28) Mycoplasma 8% (95% CI 3-13) Commensal and/or environmental bacterial flora 86% (95% CI 79-93%) S. coagulase-Negative 73% S aureus 4% Streptococcus viridans 2%	Consecutive samples but not all three analysis performed in every sample Financial support by Germitec
			Second PCR amplification after DNase treatment in positive sample (identification of infectious viral or bacterial particles)	HPV 7% (95% CI: 2– 12) Mycoplasmas 4% (95% CI: 0–8) C. trachomatis 2% (95% CIX-X)
			Ultrasound gel	Analysis 1/week: no significant microbial contamination
Casalegno et al 2012 France	Probe swab samples 1) After probe disinfection (n=200) 2) Before scan n=217	Prospective 2 studies Gynecology ward CE disposable probe cover Disinfection of probe by nurse under technician supervision	HPV after disinfection with Sani-Cloth active PCR for DNA detection of HPV	HPV (n=198): 3,5% Sampling order : 4 subsequent samples positive for the same HPV type.	Not blinded Dry swabs : loss in sensitivity No testing for viral load Funded by Germitec
			HPV before probe use PCR for DNA detection of HPV	HPV (n=216) : 2,8%
Storment JM, 1997 United States	173 women Diagnosis of threatened spontaneous abortion (n=118) possible ectopic pregnancy (n=30) pelvic pain (n=20) and pelvic mass (n=5)	Prospective Obstetrics and gynecology residents performing transvaginal ultrasound in the ED	Contamination inside condom	Blood or vaginal fluid visualized on probe : 3 (2%) Contamination of probe (hydrogen peroxide poured into condom, bubbling when in contact with secretions or blood) : 8 (5%)	Blood or vaginal fluid visualized on probe : 3 (2%) Contamination of probe (hydrogen peroxide poured into condom, bubbling when in contact with secretions or blood) : 8 (5%)
Bénet et al. 2014 France	Patients tested for HIV : 50 244 (Prevalence seropositivity : 1,4 %) Tested for HCV : 105 995 (Prevalence seropositivity : 3%)	Prospective cohort of all patients tested for HIV and HCV Single center (Lyon Hospital) Endovaginal, transrectal and transoesophageal exposures	Multivariate logistic regression adjusted for sex, age and time period	HIV prevalence not associated with previous endocavitary probe exposure (p=0,18)	Endocavitary exposure 12 months prior to testing Type of probe cover and methods of disinfection at Lyon’s Hospital not specified Ultrasounds performed in the emergency department included ? Confounder not taken into account: iv drug use, blood products transfusion
			One or more endovaginal probe exposure prevalence and adjusted odds ratio	HIV prevalence 0,5% HCV prevalence: 1,3% HIV aOR : 1,1 (95% CI 0,4-2,6) HCV aOR : 0,8 (95% CI 0,5-1,3)
			Relative risk of seroconversion HCV in patient previously exposed to endocavitary probe	RR 0,7 (95% CI 0,1-4,8, p=0,69)
Amis S et al 2000 United Kingdom	214 scans of women referred to Ovarian Cancer Screening Clinic	Prospective	Contamination of probe by routine bacterias and HSV-1 HSV-2 Transducer uncovered and wiped with a dry tissue	Bacterial swabs n =24 Viral sample n=11 1 positive for Acinetobacter sp	Swabs samples not taken systematically Criteria for sampling not specified. Not blinded
			Contamination by routine bacterias and HSV-1 HSV-2 Transducer uncovered and wiped with dry tissue then 70% v/v isopropyl alcohol wipe	Bacterial swabs n=22 Viral swabs n=15 No bacterial /viral growth
			Condoms perforation	N=214 2 noted upon visual inspection 204 tested with hydrogen peroxide : no perforation
			Sonographic coupling gel	N=25 No growth
Leroy S 2013 France	-	Systematic review Meta-analysis	Pooled estimate of probe contamination for transvaginal ultrasound after low level disinfection of probe (dry towel then towel combined to a disinfectant)	Prevalence of bacterial contamination (N=596) Pooled prevalence 12,9% (95% CI 1,7-24,3) Bacterias: Enterobacter sp, Acinetobacter sp, P aeruginosa, C cepacia, E Coli, S aureu Viral contamination (N=408) 1% (95% CI 0-10) HSV, CMV, HPV	Quality evaluation (eg PRISMA) of studies not presented Pooled prevalence not weighted for sample size Physician performing the ultrasound not specified
Kac G et al., 2010 France	Bacterial analysis n =122 Viral analysis n = 336	Prospective 3 radiology wards	Rate of bacterial contamination	Positive bacterial cultures after transvaginal examination (n=122) 3 2,5% (95%CI 0,5-7,3%)(Pseudomonas sp, Klebsiella pneumoniae)	No testing for viral load No explanation for difference in sample size between viral and bacterial contamination Bacterial load after UVC light disinfection not mentioned 2 types of probe covers (condoms n=267 and probe sheaths n=173) Ultrasound gel not analysed Swabs taken after probe cover removal but before cleaning with a towel impregnated with a disinfectant spray Financial support by Germitec
			Rate of viral contamination EBV, CMV, HPV	Viral analysis (transvaginal = 90 ; transrectal n= 336) before probe removal Presence of at least 1 virus: 56 (16,7% 95%CI 13,1-21%) HPV 28 (8,3% CI not specified) Presence of viral genome in 5 (8,9% 95% CI 3,5-19,7%) of the 56 virally contaminated After removal of probe cover 1 EBV (transvaginal)
			Evaluate efficacy of disinfection combined to UVC light	No viral genome detected

Comment(s)

Endocavitary ultrasound is used in multiple fields in medicine (urology, gynecology, cardiology, radiology and emergency medicine). Most studies on transvaginal probe contamination were conducted on obstetrics, genecology and radiology wards. Sample sizes remain small. Various probe covers and disinfecting products were used. Ultrasound coupling gel can be contaminated, therefore, it must be analysed as a potential confounder. Three studies received financial support from Germitec, a company selling a UVC light disinfectant machine for endocavitary ultrasound probes. It is worth mentioning that presence of viral DNA differs from viral load with regards to infection propagation. Finally, dry swabs may lead to lower sensitivity in microbial detection. Studies were not blinded, consequently it may have strengthened the compliance to disinfection procedures.

Clinical Bottom Line

Transvaginal ultrasound is a useful adjunct in evaluation of first semester vaginal bleeding in the emergency department. Use of a probe sheath is paramount but not sufficient, as condoms perforations were reported. Best evidence regarding probe contamination (M’Kazil et al, 2014) reported contamination with HPV, Mycoplasma and Chlamydia trachomatis. However, it is unkown whether this can lead to nosocomial infection. Also, it is possible that physician manipulations and environment contamination contribute to microbial propagation. Hence, in the emergency room, as in any other specialty performing endocavitary ultrasound exams, special attention with probe disinfection is needed. Specific studies regarding disinfecting procedures efficacy and surveillance for potential infection propagation are warranted.

References

1. Ma S.T.C., Yeung A.C., Chan PKS, Graham C.A Transvaginal ultrasound probe contamination by the human papillomavirus in the emergency department, Emergency Medecine Journa 2013;472–475
2. M’Zali F, Bounizra C, Leroy S, Mekki Y, Quentin-Noury C, et al. Persistence of Microbial Contamination on Transvaginal Ultrasound Probes despite Low-Level Disinfection Procedure PLoS ONE 2014; e93368
3. Casalegno J-S, Le Bail Carval K, Eibach D, Valdeyron M-L, Lamblin G, Jacquemoud H, Mellier G, Lina B, Gaucherand P, Mathevet P, Mekki Y, High Risk HPV Contamination of Endocavity Vaginal Ultrasound Probes: An Underestimated Route of Nosocomial Infection PLoS ONE 2012; e48137
4. Storment JM Ineffectiveness of latex condoms in preventing contamination of the transvaginal ultrasound transducer head Southern Medical Journal 1997; 206-208
5. Bénet T, Ritter J, Vanhems P Risk of Human Immunodeficiency Virus and Hepatitis C Virus Infection Related to Endocavitary Ultrasound Probe Exposure in France Infection Control and Hospital Epidemiology 2014; 1429-1431
6. Amis S, Ruddy M, Kibbler C.C, Economides D.L., MacLean A.B. Assessment of Condoms as Probe Covers for Transvaginal Sonography Journal Clinical Ultrasound 2000; 295-298
7. Leroy S Infectious risk of endovaginal and transrectal ultrasonography: systematic review and meta-analysis Journal of Hospital Infection 2013; 99-106
8. Kac G, Podglajen I, Si-Mohamed A, Rodi A, Grataloup C, Meyer G Evaluation of Ultraviolet C for Disinfection of Endocavitary Ultrasound Transducers Persistently Contaminated despite Probe Covers Infection Control and Hospital Epidemiology 2010 ; 165-170