Exposure to ultrasound in utero: epidemiology and relevance of neuronal migration studies

Written Feedback on Thermal Index During the First-Trimester Nuchal Translucency Examination Does Not Improve Compliance With the “as Low as Reasonably Achievable” Principle

Objective: The null hypothesis was that there would be no change in as low as reasonably achievable (ALARA) behavior based on feedback from comments on the nuchal translucency quality review (NTQR) image submissions. Methods: A review of the Perinatal Quality Foundation Database found 206 practitioners who failed their first credential attempt and received ALARA comments as feedback. The second submissions of the same subjects were reviewed to determine if compliance with ALARA improved following written feedback. Results: Seventeen percent of all second submissions addressed ALARA. Sixty-one percent of second submissions passed, however only 18.4 % of those addressed ALARA. Among those who submitted thermal index at bone values on both first and second submissions, the mean values on the second submission were 0.20 lower compared to the first submission ( P = .0288). Second submission mean thermal index at bone values were 0.68 lower among those submissions with ALARA concerns addressed compared to those not addressing these concerns ( P < .001). Conclusions: Written feedback without consequences on the ALARA principle did not improve compliance.

'Ultrasound is an invaluable third eye, but it can't see everything': a qualitative study with obstetricians in Australia

Background

Obstetric ultrasound has come to play a significant role in obstetrics since its introduction in clinical care. Today, most pregnant women in the developed world are exposed to obstetric ultrasound examinations, and there is no doubt that the advantages of obstetric ultrasound technique have led to improvements in pregnancy outcomes. However, at the same time, the increasing use has also raised many ethical challenges. This study aimed to explore obstetricians’ experiences of the significance of obstetric ultrasound for clinical management of complicated pregnancy and their perceptions of expectant parents’ experiences.

Methods

A qualitative study was undertaken in November 2012 as part of the CROss-Country Ultrasound Study (CROCUS). Semi-structured individual interviews were held with 14 obstetricians working at two large hospitals in Victoria, Australia. Transcribed data underwent qualitative content analysis.

Results

An overall theme emerged during the analyses, ‘Obstetric ultrasound - a third eye’, reflecting the significance and meaning of ultrasound in pregnancy, and the importance of the additional information that ultrasound offers clinicians managing the surveillance of a pregnant woman and her fetus. This theme was built on four categories: I:‘Everyday-tool’ for pregnancy surveillance, II: Significance for managing complicated pregnancy, III: Differing perspectives on obstetric ultrasound, and IV: Counselling as a balancing act. In summary, the obstetricians viewed obstetric ultrasound as an invaluable tool in their everyday practice. More importantly however, the findings emphasise some of the clinical dilemmas that occur due to its use: the obstetricians’ and expectant parents’ differing perspectives and expectations of obstetric ultrasound examinations, the challenges of uncertain ultrasound findings, and how this information was conveyed and balanced by obstetricians in counselling expectant parents.

Conclusions

This study highlights a range of previously rarely acknowledged clinical dilemmas that obstetricians face in relation to the use of obstetric ultrasound. Despite being a tool of considerable significance in the surveillance of pregnancy, there are limitations and uncertainties that arise with its use that make counselling expectant parents challenging. Research is needed which further investigates the effects and experiences of the continuing worldwide rapid technical advances in surveillance of pregnancies.

The ultrasound frequency determines the degree of intrinsic coagulation activation

Diagnostic ultrasound activates intrinsic coagulation. The aim of the present work was to quantify the action of different ultrasound frequencies on the contact phase of human blood coagulation. Pooled normal citrated platelet-poor plasma in 2 ml aliquots in polypropylene monovettes was exposed to diagnostic ultrasound, changing the ultrasound frequency from 17 to 15 to 12 to 8 to 7 MHz (at an intensity of 1.1 MI). After 0-2 min (23°C), 400 μl samples were withdrawn and placed into polypropylene Eppendorf cups. Forty microliters of plasma sample was pipetted into U-wells polystyrene microtiter plates of high purity (Brand781600). Immediately thereafter, the recalcified coagulation activity assay (RECA) was performed. Seventeen megahertz ultrasound exposure was the weakest activator of intrinsic coagulation of all frequencies tested: even 2 min of exposure at 23°C enhanced F2a generation by only about three-fold. The shorter the ultrasound exposure, the better the action against intrinsic hemostasis: 0.5 min of ultrasound exposure at 23°C induced less than two-fold thrombin generation in all frequencies tested. One minute ultrasound exposure (23°C) triggered intrinsic coagulation strongest at 8 MHz, showing an approximately four-fold increase in F2a generation. A 1.5 min of ultrasound exposure (23°C) triggered coagulation strongest at 7 MHz, showing an approximately 14-fold increase in F2a generation. Two minute of ultrasound exposure (23°C) triggered coagulation strongest at 15 MHz, showing an approximately 18-fold increase in F2a generation. Ultrasound has to be considered as a potential inducer of pathologic systemic coagulation. Patients at risk for increased coagulation activation and/or liver insufficiency should be protected with low molecular weight heparin, if a prolonged ultrasound diagnostic is planned. Ultrasound frequencies of about 17 MHz are the weakest activators of intrinsic coagulation. Ultrasound frequencies of about 7 MHz might be used for therapeutic induction of coagulation activation, such as in patients with severe cerebral or hepatic hemorrhages.

Ultrasonic imaging: safety considerations

Modern ultrasound imaging for diagnostic purposes has a wide range of applications. It is used in obstetrics to monitor the progress of pregnancy, in oncology to visualize tumours and their response to treatment, and, in cardiology, contrast-enhanced studies are used to investigate heart function and physiology. An increasing use of diagnostic ultrasound is to provide the first photograph for baby's album-in the form of a souvenir or keepsake scan that might be taken as part of a routine investigation, or during a visit to an independent high-street 'boutique'. It is therefore important to ensure that any benefit accrued from these applications outweighs any accompanying risk, and to evaluate the existing ultrasound bio-effect and epidemiology literature with this in mind. This review considers the existing laboratory and epidemiological evidence about the safety of diagnostic ultrasound and puts it in the context of current clinical usage.