Effect of different needleless connector technologies on backflow volume in the long peripheral catheter: A bench study

Background: The backflow phenomenon represents a challenge when using needleless connectors. This bench study investigated backflow volume (i.e. the quantifiable amount of backflow) into a long peripheral catheter by evaluating needleless connectors with four technologies (positive, negative, neutral, and anti-reflux) and three clamping sequences. Methods: Four different connectors with varying displacement technologies were tested to assess backflow volume using the manufacturer’s recommended clamping sequences and a sequence in which the clamp was not foreseen. A high-fidelity experimental model was used. Neutral and anti-reflux needleless connectors were evaluated with varying clamping sequences. The backflow volume values are presented as median and interquartile range. Results: Backflow was observed in all cases, with a wide range of results: the lowest backflow volume was recorded with the anti-reflux connector, while the highest was recorded with the negative connector, both when no clamp was used. The clamp significantly reduced backflow volume in negative and positive connectors, while no differences were noted between neutral and anti-reflux types across the sequences. Conclusion: Using only needleless connectors in long peripheral catheters does not prevent the backflow phenomenon. Using clamps significantly reduced the backflow volume in needleless connectors with positive and negative displacement. Neutral and anti-reflux connectors perform similarly in the clamping sequences with and without clamps. © The Author(s) 2025.