好消息是尽管WHO取消了回血要求，但是不少护士仍然会回血，不过只有2%的护士按照标准回血流程操作。

Blood Aspiration During IM Injection

[url]https://pubmed.ncbi.nlm.nih.gov/25784149/[/url]

Results noted that 74% of the sample continue to aspirate at least 90% of the time. Of the participants who continue to aspirate, only 3% aspirate for the recommended 5 to 10 s. Forty percent reported having aspirated blood at least once, whereas 6 RNs (4%) noted blood aspiration ≥13 times.