Reply to Letter to the editor: Safety of contrast-enhanced ultrasound using microbubbles in human pregnancy: A scoping review

Dear editor,

We are grateful for the interest of the respondent on our scoping review concerning the safety of contrast-enhanced ultrasound using microbubbles during pregnancy and appreciate the thoughtful comments. The points raised highlight important aspects of methodology and evidence interpretation that merit further elaboration.

First, we appreciate the suggestion to clarify our choice of a scoping review over a systematic review to strengthen our findings. Our decision was driven by the shortage of literature and heterogeneity of data in this field. Scoping reviews are well-suited for exploring existing literature and identifying the gaps, especially in areas that are under-researched. For this topic, we believe it is essential to first identify the knowledge gaps to effectively guide future research. However, we agree that explicitly justifying this methodological choice in the review would have provided better context and transparency for our objectives.

Regarding the inclusion criteria for this scoping review, we recognize the limitations of incorporating case reports and studies available only in abstract form. These study types often lack detailed reporting and methodological rigor, which limits their reliability. However, they were included to ensure that the review captured the broadest possible range of evidence, given the limited data available on this topic. We fully acknowledge that the quality of the included case reports and study abstracts is limited, which is why our conclusions in this review are cautiously positive towards the safety of contrast-enhanced ultrasound (CEUS) in pregnancy. Our findings aim to provide an initial understanding of the safety profile of CEUS in pregnancy but should not be interpreted as definitive. Therefore, we emphasize the need for more rigorous studies to strengthen and expand the evidence.

We also appreciate the critical feedback on our reliance on delivery mode and term as safety indicators. While these were commonly reported outcomes in the studies reviewed, we recognize that they not always reflect the safety of CEUS in pregnancy, particularly in complex clinical scenarios influenced by maternal pathology. Therefore, we only noted that no complications specifically connected to CEUS were described rather than reporting that CEUS was safe. We recognize that the absence of reported complications does not necessarily equate to safety, especially when other important safety indicators were not addressed in the data.

Expanding the analysis to include broader safety outcomes, such as neonatal and fetal health in relation to gestational age at exposure, is indeed critical. By emphasizing these limitations, we hope our work serves as a steppingstone for future research to build upon. We appreciate the constructive feedback, which underlines the importance of methodological rigor in synthesizing evidence for clinical guidance. These insights will undoubtedly guide improvements in future reviews on this topic.

Publication History

Article published online:
11 February 2025