Background: Foam sclerotherapy is an effective treatment strategy for vascular malformations, and its sclerosing power depends on foam stability. Twenty quick passages have been widely used as an indicator of the most stable state of sclerosants, but the universality of their effectiveness has not been proven yet.
Objective: We aimed to identify simple and objective indicators of the most stable state of commonly used sclerosants and provide practitioners with suggestions to judge when foam producing is completed in sclerotherapy.
Materials and methods: The universality of the effectiveness of 20 passages was tested by producing bleomycin foam with different passages. Further study was performed by testing modified bleomycin, polidocanol, and sodium tetradecylsulfate foam.
Results: The bleomycin foam became denser as passages were added, and the sound of each passage became almost silent after 40 passages. The almost silent sound can be an indicator of foam stability for most sclerosants. It has a different application range compared with 20 quick passages.
Conclusion: We suggest that practitioners choose a different indicator depending on the foam used.