Visible clots in implanted vascular access devices (IVADs) warrant aspiration prior to maintenance flushing, especially when flush intervals are extended beyond the manufacturer’s recommendations. These study findings were published in the Clinical Journal of Oncology Nursing. 

The evidence on the best flushing frequency for IVADs is insufficient. Manufacturers recommend a 4-week schedule, whereas guidelines suggest a 12-week schedule is functionally safe. 

This observational pilot study reviewed data from the Everett Clinic at Providence Regional Cancer Partnership in Washington. Fifty-nine patients who were scheduled for a maintenance flush or laboratory draw between June 1, 2021, and August 31, 2021, were included in this analysis. During the study period, nurses followed a 9-step no flush, dry-pull protocol. The primary outcome was the instance of abnormal-appearing substances or occlusions in the contents of the IVAD reservoir at aspiration based on flush timing.

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Overall, 3 patients underwent flushing at 5 to 8 weeks, 9 at 9 to 12 weeks, 23 at 13 to 16 weeks, and 24 at 17 or more weeks. Overall, abnormal-appearing reservoir contents were observed in 15 patients. Most abnormalities occurred in the 13 to 16 weeks (8 patients) and 17 or more weeks (6 patients) interval groups.

The abnormal substances included visible clots, discoloration, and atypical consistency.

The limitations of this study included the small sample size and single-center design, which did not allow testing for statistical significance.

“This observational study showed that visual changes occurred in 25% of the 59 patients observed, and risk of flushing abnormal-appearing contents into the bloodstream was feasible. Aspirating prior to flushing may be an initial step to ensure reservoir contents are discarded if noticeable abnormal appearance is observed,” concluded the study authors.

Disclosures: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


McManus M, Sarver MJ, Ser E, Gross KR. Safety of extending implanted vascular access device maintenance flush frequency. Clin J Oncol Nurs. 2023;27(2):165-171. doi:10.1188/23.cjon.165-171