Correction: The Ultrasound Journal (2021) 14:2 https://doi.org/10.1186/s13089-021-00250-6

After publication of the original article [1], concerns have been raised that the trial described in this article does not match the Trial Registration record (ISRCTN77929274) provided in the article. Authors explained how their research evolved over time and have provided evidence of ethics approval that matches the research described in the article. On advice from the Editor, the authors have retrospectively registered this trial with the correct details and description under the following number: ISRCTN14491490.

The original article [1] has been updated.