The handles of most vaginal ultrasound probes are contaminated with potentially dangerous bugs, according to a snapshot study.
But the probes are still safe and there have been no reported transfers of infections, says researcher Dr Glenn McNally.
His study at a hospital and a private practice shows that 70 per cent of probe handles have bugs, including those responsible for bladder infections.
In one case, a handle was contaminated with dangerous MRSA superbug.
The probes are used for several medical investigations, including annual checks and the monitoring of pregnancy.
Doctors typically wear protective gloves and cover the probe with a condom.
In most cases, the probes are cleaned with liquid disinfectant.
Dr McNally, the past president of the Australasian Society of Ultrasound in Medicine, presented the results of his study at an international conference in Sydney on Wednesday.
He says the study helps doctors appreciate that handles are a potential source of infection.
"It is not just the tip of the probe that we should be concerned about."
The study was sponsored by Nanosonics, an Australian company that makes a device designed to disinfect the entire probe.