Foetal ultrasound scans are a safe and essential medical tool, according to an expert in these procedures, despite new findings that indicate ultrasound could affect cells in the body.
The researcher at St Vincent's Hospital, who discovered that scanned mice experienced more rapid cell death and slower cell growth, has also urged caution about the findings, describing them as preliminary.
"Ultrasound has been around for 30 years," stated Dr Peter McParland, director of the foetal assessment unit at the National Maternity Hospital, Holles Street. His own unit performed about 15,000 scans a year and other Dublin maternity hospitals were just as busy.
The scans reflect inaudible sound waves off internal tissues to produce images on a screen. They give views of internal organs without making incisions or inserting probes.
"To the best of my knowledge there has never been a well-documented report of harm from ultrasound," he stated. "Ultrasound is of value but must be used judiciously and prudently. It should only be used when there is a medical reason for it."
Doctors came under pressure from parents who wanted to learn the gender of their child, but "we should not be doing scans for social reasons", he said.
The original work was done by Dr Patrick Brennan of the school of diagnostic imaging at University College, Dublin, based at St Vincent's Hospital. He also urged caution in drawing too many conclusions from his findings. "There is no reason why people should not continue having scans," he said. "It is preliminary work."
Dr Brennan and colleagues Ms Marie Stanton and Dr Raj Ettarh gave 12 mice an eight-megahertz scan lasting for 15 minutes. Scans using three to 10 megahertz are common in human medical use.
The researchers checked cells in the small intestine and found that cell division, a measure of growth, slowed by 22 per cent, while the rate of natural cell death doubled 41/2
hours after exposure. Dr Brennan could not say whether these changes persisted after this time. "My guess would be that things would return to normal," he said.
"At the moment we don't have to be concerned. The main message from the work is we have to do more work," Dr Brennan said yesterday. "I would say, don't panic. We have seen these changes in low doses of radiation and they mean absolutely nothing."
