title: Determining "true" leukocytosis in bloody joint aspiration.
abstract: This study intends to determine the diagnostic value of implementing a corrective formula that can adjust for serum leukocytes in bloody joint fluid. Our cohort included 91 infected and 37 aseptic total knee arthroplasties. Joint fluid leukocyte count (>1760/microL) and neutrophil percentage (>73%) were the cutoff values for deep infection. The adjusted fluid leukocyte counts were calculated using the following simple formula: WBCadjusted=WBCobserved-[(WBCblood x RBCfluid/RBCblood)]predicted. Adjusted fluid cell counts of only 5 infected patients dropped below the cutoff value, whereas the remaining 86 maintained a high cell count. Ten noninfected patients had false-positive cell counts, 6 of which were successfully corrected to levels below the designated thresholds. The aspirates that were corrected had a greater number of introduced white blood cells. This study suggests that our corrective formula can detect false-positive joint aspirations without jeopardizing the diagnosis of periprosthetic infection.
authors.affiliation: Rothman Institute of Orthopedics, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: Elie
authors.initials: E
authors.lastname: Ghanem
authors.forename: Carrie
authors.initials: C
authors.lastname: Houssock
authors.forename: Luis
authors.initials: L
authors.lastname: Pulido
authors.forename: Seungbeom
authors.initials: S
authors.lastname: Han
authors.forename: Fereidoon M
authors.initials: FM
authors.lastname: Jaberi
authors.forename: Javad
authors.initials: J
authors.lastname: Parvizi
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005122:Exudates and Transudates / Q000166:cytology; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007958:Leukocyte Count / Q000379:methods*; D007964:Leukocytosis / Q000175:diagnosis*; D008297:Male; D011183:Postoperative Complications; D016459:Prosthesis-Related Infections / Q000175:diagnosis*