Sonography/Ultrasound Protocol and Safety Standards

Sonography/Ultrasound Protocol and Safety Standards

A senior research projected submitted in partial requirement for the degree Doctorate of Chiropractic.

Logan University Sterling Foster

Advisor: Mary Unger-Boyd, DC, DICS, CACCP

December 2013

Page 1 Sonography/Ultrasound Protocol and Safety Standard. By: Sterling Foster

Abstract: The evolution of the diagnosis and management of women who are pregnant has been a medical success over the past years. Pregnancy confirmation was once determined by amenorreaic symptoms in the presence sexual activity accompanied by a feeling of "morning sickness." It progressed into a pregnancy test that has reached a level of sensitivity and specificity which is unlikely to be surpassed either by better tests or alternative technology.22 currently, confirmation of pregnancy is being achieved through visualization of the fetus with sonography. The biophysical effects of the ultrasound are damaging to energy sensitive structures of the fetus if >1.5 TI or MI is exceeded. User incompetence is identified through poor knowledge of safety standards on sonography equipment through questionnaires. These factors must be acknowledged when discussing routine, low-risk ultrasoundography. Methods: A comprehensive review of the literature is performed. Information was inserted in Cochrane database of Systematic Review, PubMed, and Google Scholar in an attempt to identify the presence of specific practice guidelines when performing prenatal ultrasounds/sonography. Conclusion: ODS safety standards issued by the FDA exceed levels that may be harmful too the developing fetus, especially the first trimester, when sonography is used improperly by the end user. Further research is needed in regards to regulation standards for ultrasound technicians. Keywords: sonography, ultrasound, safety, efficacy, complication, protocol and procedure.

Page 2 Sonography/Ultrasound Protocol and Safety Standard. By: Sterling Foster

Introduction:

The evolution of the diagnosis and management of women who are pregnant has been a medical success over the past years. Pregnancy confirmation was once determined by amenorreaic symptoms in the presence of sexual activity accompanied by a feeling of "morning sickness." It progressed into a pregnancy test that has reached a level of sensitivity and specificity which is unlikely to be surpassed either by better tests or alternative technology.22 Currently, confirmation of pregnancy is being achieved through visualization of the fetus with sonography. The complications of the first two remain minimal, however evidence regarding the safety of the latter is rarely, if ever, reviewed or questioned. Modern sophisticated ultrasonographic equipment is capable of delivering substantial levels of acoustic energy into the body when used at maximum outputs.20 Establishing the boundaries for obstetrical intervention is important for the health of the mother and child during the gestational period. Identifying key factors for neonatal mortality are important, but routine ultrasound does not increase these chances. The New England Journal of Medicine reported screening ultrasonography did not improve prenatal outcome as compared with the selective use of ultrasonography on the basis of clinician judgment.1 With such similarity existing between the two groups it should become even more important to thoroughly analyze the safety of emitting routine ultrasonography to a developing fetus without first evaluating the potential for harm. High-energy ultrasound can induce biophysical effects when passing through tissue, for example, thermal effects and mechanical stress, causing cavitations. Standard ultrasound protocols and procedures should be in place to prevent abuse or harm to the fetus and

Page 3 Sonography/Ultrasound Protocol and Safety Standard. By: Sterling Foster

regulation should strictly adhered to. This literature review evaluates the potential side effects of ultrasound, diagnostic usage, and safety protocols of the end-user.

Page 4 Sonography/Ultrasound Protocol and Safety Standard. By: Sterling Foster

Discussion:

Biophysical Effects: The FDA mandates that machines capable of producing higher outputs be able to display to the diagnostician some indication of the relative potential for ultrasoundinduced bioeffects. This regulation is known as the Standard for Real-Time Display of Thermal and Mechanical Acoustic Output Indices on Diagnostic Ultrasound Equipment, more commonly known as the output display standard (ODS).15 The ODS indicators comprise two types of biophysical index: the thermal index (TI) and mechanical index (MI)10 The ODS supplies on screen, in real time, numerical displays that provide information about the potential for temperature increases (TI) and mechanical damage (MI).14 These indices are calculated for the given machine settings on the basis of tissue models and their acoustic properties.

The TI is an estimate of the tissue temperature rise in degrees centigrade (?C). For particular examination situations, three types of TI have been defined: soft tissue (TIS), bone tissue (TIB) thermal index, and for cranial examinations (TIC). The presence of bone within the ultrasound beam greatly increases the likelihood of a temperature rise due to direct absorption in the bone itself and conduction of heat from bone to adjacent tissues.16 A temperature elevation less than 1.5?C likely does not present a bioeffects risk to the embryo, although there has been some debate on the threshold nature of thermal effects. A temperature elevation greater than 4?C for 5 minutes can present a bioeffects risk to the embryo. Biologically significant temperature increases can occur at or near to bone in the fetus from the second trimester, if the beam is held stationary for more than 30 s in some pulsed Doppler applications.21 Velocity, power, and pulsed spectral Doppler ultrasound all have the potential to

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