Preanalytical quality in clinical chemistry laboratory

Haemolysis is usually caused by inadequate specimen collection or preanalytical handling and is suggested to be a suitable indicator of preanalytical quality. We investigated the prevalence of detectable haemolysis in all routine venous blood samples in OPDs and IPDs to identify differences in preanalytical quality.

Haemolysis index (HI) values were obtained from a Vitros 5,1 in the routine clinical chemistry laboratory for samples collected in the outpatient department (OPD) collection centres, a hospital, and inpatient departments (IPD). Haemolysis was defined as a HI > or = 15 (detection limit).

Samples from the OPD with the highest prevalence of haemolysis were 6.1 times (95% confidence interval (CI) 4.0 - 9.2) more often haemolysed compared to the center with the lowest prevalence. Of the samples collected in primary health care, 10.4% were haemolysed compared to 31.1% in the IPDs (p = 0.001). A notable difference in haemolysed samples was found between the IPDs section staffed by emergency medicine physicians and the section staffed by primary health care physicians (34.8% vs. 11.3%, p = 0.001).

The significant variation in haemolysis indices among the investigated units is likely to reflect varying preanalytical conditions. The HI is a valuable tool for estimation and follow-up of preanalytical quality in the health care laboratory.