401072 Lecture Notes - Lecture 9: Obstetric Ultrasonography, Randomized Controlled Trial, Perinatal Mortality
Document Summary
Current evidence indicates that diagnostic ultrasound is safe for the unborn child, unlike radiographs, which employ ionising radiation. Randomised control trials have followed children up to ages 8 9, with no signi cant differences in vision, hearing, school performance, dyslexia, or speech and neurologic development by exposure to ultrasound. In one randomized trial, the children with greater exposure to ultrasound had a reduction in perinatal mortality, and was attributed to the increased detection of anomalies in the ultrasound group. The 1985 maximum power allowed by the u. s. food and drug administration (fda) of 180 milliwatts per square cm is well under the levels used in therapeutic ultrasound, but still higher than the 30-80 milliwatts per square cm range of the. Doppler ultrasonography examinations has a thermal index (ti) of about ve times that of regular (b-mode) ultrasound examinations. several randomized controlled trials have reported no association between doppler exposure and birth weight, apgar scores, and perinatal mortality.
