A retrospective analysis of the aspiration of fracture blisters

Fracture blisters are frequently encountered in orthopaedic trauma. Fracture blisters are associated with increased infection rates and wound breakdown. This study was performed to determine whether fluid aspirate from blisters is sterile or colonized.

This is a retrospective review of a prospectively gathered cohort of patients. Patients with fracture blisters were recruited from a U.S. level I trauma center between 2011 and 2017. The blisters were aspirated under sterile conditions. Fluid was analyzed for gram stain and quantitative culture. Medical history obtained included blister location, presence of blood in blister, injury mechanism, gender, diabetes status and tobacco use. The demographic and behavioral descriptors were compared across positive aspirate or infection status using chi-square and Fisher's exact tests.

We enrolled 64 patients in the study, seven of which had colonized aspirates (10.9%). None of the potential risk factors were significantly associated. Tobacco use trended towards significance for a positive aspirate (p = 0.09), but not for infection (p = 0.61). We followed patients for an average of 4.6 months. Four patients went on to have surgical site infections and none of them had positive aspirates.

Fracture blisters cannot be assumed to be sterile with more than 10% of our sample being colonized. Blister rupture during surgery or prepping for surgery could represent a contamination of the sterile field. No risk factors were significantly associated with colonization in our sample. However, colonized aspirates may not predispose patients to increased infection rates.