Neutrophil Cell Population Indicates Postsurgical Infection

The modern fully automated hematology analyzer can determine white blood cell counts (WBC) with differentials and determine their intrinsic biophysical properties, known as cell population data (CPD).

The morphologic changes of reactive neutrophils in septic patients can be quantitatively measured by the analyzer and the neutrophil CPD, such as mean neutrophil volume (MNV) and neutrophil volume distribution width (NDW), are significantly increased not only in septic patients with high WBC, but also in those with normal or low WBC.

Hematologists at the Nantong University (China) investigated the clinical usefulness of MNV and NDW to differentiate postoperative infection. They analyzed the cell population data from 212 controls, 135 patients without postsurgical infection, and 62 with infection between April 2009 and April 2011. All patients had normal WBC and percent neutrophils prior to surgery,

Neutrophil CPD parameters were generated during automated differential analysis by each individual cell passing through the aperture and were optically and electronically measured using the Coulter LH 750 (Beckman Coulter, Brea, CA, USA). The conventional parameters, such as WBC count and percent neutrophils were also collected. All specimens were analyzed within four hours after collection.

There were no significant differences in MNV and NDW observed before surgery between infected and uninfected patients when compared with controls. The MNV and NDW in infected patients were significantly increased after surgery when compared with uninfected patients. Although WBC and percent neutrophils were also increased after surgery, no statistical differences were seen between uninfected and infected patients. A MNV cutoff of ≥152.3 and NDW cutoff of ≥24.2 produced 90.3% and 88.3% sensitivity and 88.4% and 76.3% specificity, respectively.

The authors concluded that the parameters generated during automated differential analysis, without additional specimen requirements, are quantitative, more objective, and more accurate than manual differential counts, because over 8,000 leukocytes are simultaneously evaluated. In addition, they have shown a better diagnostic performance than manual band neutrophil count, absolute neutrophil counts, and C-reactive protein, which are traditionally used as indicators for acute infection. The study was published in the June 2012 issue of the International Journal of Laboratory Hematology.

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Nantong University
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