Effects of blood contamination on peritoneal D-dimer concentration in horses with colic.

Abstract

BACKGROUND: Peritoneal D-Dimer concentration can be determined to assess peritoneal fibrinolysis activity in horses with gastrointestinal disorders. However, blood contamination of peritoneal fluid may occur during collection and could alter peritoneal D-Dimer concentration. HYPOTHESIS/OBJECTIVES: Blood contamination in peritoneal fluid does not affect interpretation of peritoneal D-Dimer concentration in horses with colic. ANIMALS: Thirty-four horses with colic and 4 healthy horses. METHODS: Peritoneal fluid and blood samples were simultaneously collected upon admission. Then, peritoneal fluid was serially contaminated with the horse's own blood; final contaminations corresponded to 1, 5, 10, and 20% of blood in peritoneal fluid. D-Dimer concentration was determined in blood, peritoneal fluid, and contaminated peritoneal fluid samples. Data were analyzed using a longitudinal linear model and a generalized estimating equations analysis to assess the quantitative and qualitative variations of the effect of blood contamination on peritoneal D-Dimer concentration. RESULTS: Peritoneal D-Dimer concentration was only quantitatively affected when peritoneal fluid was contaminated at 20% of blood. However, when using increasing cut-off values of peritoneal D-Dimer concentration (100, 2,000, 8,000, and 16,000 ng/mL), this effect disappeared at the highest cut-off values (8,000 and 16,000 ng/mL). When peritoneal fluid contamination was grouped as "minimally contaminated" (< or =1% of blood) and "highly contaminated" (> or =5% of blood), no significant differences on D-Dimer concentration between both groups at each cut-off value were observed. CONCLUSIONS AND CLINICAL IMPORTANCE: Although quantitative results of peritoneal D-Dimer concentration could be affected by high levels of blood contamination (> or =20%), interpretation of increased peritoneal fibrinolytic activity was not significantly affected.