Bioeffects and Safety of 2D and 3D/4D Ultrasound in Obstetrics—Is there a Place for “Parental Bonding” Scans? 17 Bioeffects and Safety of 2D and 3D/4D Ultrasound in Obstetrics—Is there a Place for “Parental Bonding” Scans? Jacques S Abramowicz Department of Obstetrics and Gynecology, and Fetal and Neonatal Medicine Program, Rush University 1653 West Congress Parkway, Chicago, IL 60612, USA Tel: 312-942-9428, e-mail: Jacques_abramowicz@rush.edu Donald School Journal of Ultrasound in Obstetrics and Gynecology, October-December 2008;2(4):17-21 Abstract: Ultrasound is widely used in daily clinical obstetrical practice. Many medical indications exist for performing a sonographic examination but, in addition, several researchers have published information on the importance of patients watching the ultrasound monitor during the examination, particularly during three- and four- dimensional (3D/4D) scanning, for maternal-fetal bonding. Furthermore, a certain form of ultrasound, called “entertainment” or “keepsake” ultrasound has flourished, particularly in the United States. While ultrasound is assumed to be completely safe, it is a form of energy and, as such, has effects in tissues it traverses (= bioeffects). The two most important mechanisms for effects are thermal and non-thermal. Non- thermal mechanisms include cavitation, streaming, and even release of free radicals. These two major mechanisms are indicated on-screen by two indices: The thermal index (TI) and the mechanical index (MI). It is important to be aware of these effects to be able to prevent potential harm. Ultrasound machine controls can alter the instrument acoustic energy and hence the exposure but different machines behave differently. Therefore each clinician should know how this occurs in his/her own machine. Unfortunately, it appears the general knowledge in this area is poor and an effort should be made to educate the end- users. Whether 3D/4D enhances parental-fetal bonding is still a matter of discussion. Keywords: Ultrasound, bioeffects, safety, maternal-fetal bonding. INTRODUCTION Ultrasound has become the most commonly utilized diagnostic imaging modality in obstetrics and gynecology. It is found in every academic department, both of Obstetrics/ Gynecology and Radiology, as well as in many private offices. In addition, stores are opening in malls over the USA, and, more recently in Europe, where pregnant patients can have an “entertainment” or “keepsake”, non-medical ultrasound. The reasons for the extensive use of this modality are multiple: ultrasound is relatively easy to use (after appropriate training), results are immediately available, it is non-invasive and of relatively low cost when compared to other imaging modalities. Furthermore it has, so far, a perfect safety record. Besides some accepted clinical value in obstetrics, for instance adequate gestation dating and diagnosis of fetal abnormalities, it may have additional benefits such as increased bonding between future parents and their unborn child. Several modalities have been introduced in recent years: from spectral and color Doppler to three-dimensional/four-dimensional (3D/4D) ultrasound and ultrasound contrast agents. Several issues need to be addressed: 1. Can diagnostic ultrasound, as utilized in daily obstetrical clinical practice have effects on tissues and can these effects be harmful? This can be simply asked as: Is ultrasound safe for the fetus? 2. Is there any evidence that watching 3D/4D ultrasound on a monitor increases maternal-fetal (and, to some extent, paternal-fetal) bonding? Bioeffects and Safety of Ultrasound in Obstetrics Despite its widespread use, many scientists have expressed concern about the potential risks to the fetus. This began in the early days of diagnostic ultrasound, 1,2 has continued over the years, 3-17 with many cautioning against indiscriminate ultrasound exposure, as could, nowadays, entertainment ultrasound be considered. Ultrasound is a form of energy and, as such, has effects in tissues it traverses, i.e. biological effects, also called bioeffects. 18 The two major ones are local heating, the thermal effect, and tissue reaction to alternating positive and negative pressure, the non-thermal effect (also called mechanical) which includes effects that are not purely mechanical, such as chemical or physical. 19 It is important to consider what has happened over the years to acoustic outputs of clinical machines. In the United States, the original maximal outputs for different clinical applications date from 1985. 20 The spatial peak temporal average intensity (I SPTA, in mW/cm 2 ) was set at 17, 94, 430 and 720 mW/cm, 2 respectively, for ophthalmic, obstetrics, cardiac and peripheral vascular applications. Around 1991, there was a remarkable change in the regulations regarding