Israel Medical Association Journal

The use of ultrasound endovaginal probes is common practice in the fields of gynecology and obstetrics. The vagina serves as a host environment for many microorganisms, contributing greatly to its defensive mechanisms. It is not known whether the introduction of other microorganisms into the vaginal region are detrimental or require intensive preventative measures. Several national ultrasonography societies, as well as the Israel Ministry of Health, have addressed the proper and adequate handling of sonographic endovaginal probes, including the use of high-level disinfecting agents following cleansing and prior to using probe covers between patients. However, many obstetrics and gynecology ultrasound units in Israel find it difficult to adhere to these strict disinfecting requirements. While most of the guidelines are based on the theoretical risk of contaminations when ultrasound endovaginal probes are used, the rate of nosocomial infections linked to the use of these probes has yet to be verified. Based on the information available, there is an urgent need to find a solution that enables gynecological ultrasound users to properly disinfect endovaginal probes between patients. Currently, it is almost impossible to pragmatically adhere to the Israel Ministry of Health guidelines. 

Background: Nebulized hypertonic saline (HS) treatment is unavailable to large populations worldwide.

Objectives: To determine the bacterial contamination and electrolyte concentrations in homemade (HM-HS) vs. pharmacy made (PM-HS).

Methods: We conducted three double-blind consecutive trials: 50 boiled-water homemade 3%-HS (B-HM-HS) bottles and 50 PM-HS. The bottles were cultured after 48 hours. Electrolyte concentrations were measured in 10 bottles (5 per group). Forty bottles (20 per group) were distributed to volunteers for simulation of realistic treatment by drawing 4 ml HS three times daily. From each bottle, 4 ml samples were cultured after 1, 5, and 7 days. Volunteers prepared 108 bottles containing 3%-HS, sterilizing them using a microwave oven (1100–1850W). These bottles were cultured 24 hours, 48 hours, and 1 month after preparation.

Results: Contamination rates of B-HM-HS and PM-HS after 48 hours were 56% and 14%, respectively (P = 0.008). Electrolyte concentrations were similar: 3.7% ± 0.4 and 3.5% ± 0.3, respectively (P = NS). Following a single day of simulation B-HM-HS bottles were significantly more contaminated than PM-HS bottles: 75% vs. 20%, respectively (P < 0.01). By day 7, 85% of PM-HS bottles and 100% of B-HM-HS bottles were contaminated (P = 0.23). All 108 microwave-oven prepared bottles (MICRO-HS) were sterile, which was significantly better than the contamination rate of B-HM-HS and PM-HS (P < 0.001). Calculated risk for a consecutive MICRO-HS to be infected was negligible.

Conclusion: Microwave preparation provides sterile HS with adequate electrolyte concentrations, and is a cheap, fast, and widely available method to prepare HS.