Use of pulsed Doppler ultrasound in 1st trimester uncomplicated pregnancy: Is there reason for concern?

The advent of pulsed spectral Doppler (PD) and colour flow imaging (CFI) has led to significant improvements in ultrasound diagnostic capabilities in obstetrics and perinatal applications. There is a increasing trend to use ultrasound at early stages of pregnancy, when the developing embryo is known to be highly sensitive to damage by physical agents. Regulation of intensity limits, in the USA, has been relaxed for equipment that provides an output display. It is accepted internationally that the maximum operating acoustic outputs of modern sophisticated equipment can produce biological effects, such as significant temperature increase in the fetal brain. Non-thermal effects observed in animals include bleeding in tissues of the lung and intestine, at gas body interfaces. Haemorrhage of the soft tissue near bone has been reported in fetal mice. The important question to address is, whether, or not, such biological effects will have significant consequences on human fetal development. This presentation discusses the effectiveness of output displays and summarizes the potential risk factors associated with the use of Doppler ultrasound in uncomplicated early pregnancy.