Estimated National Volume of Laboratory Results Affected by Hemolyzed Specimens From Emergency Departments

We read with great interest the articles by Howanitz and colleagues^1,2  regarding hemolysis in hospital laboratory specimens. The hemolysis rates among the 722 laboratories studied ranged from less than 1% up to 36%, consistent with previous publications reporting rates as high as 30% for specimens obtained in emergency departments (EDs).^1,3  A Q-Probes survey by the College of American Pathologists showed that 71% of laboratories reported little to no progress in addressing the problem of hemolyzed specimens.²  Hemolysis is common among blood samples obtained in EDs,³  potentially affecting results on several analytes in metabolic panels, which remain one of the most commonly ordered tests. Hemolysis may produce unreliable laboratory values requiring unnecessary repeated testing that results in excess patient discomfort, higher costs, increased nursing time, and delays to definitive acute care.

Hemolysis most often results from damage to red blood cells during collection. Preanalytic processes (both technique and equipment) play a significant role in hemolysis rates.^3,4  Hospital EDs have been identified as a source of hemolyzed samples, with observed percentages of affected specimens ranging from 6.8% to 19.8%, and some as high as 30%; these levels are markedly elevated compared with other hospital departments.³  The American Society for Clinical Pathology established a benchmark of 2% or lower for hemolysis rates among laboratory blood samples, and most collection sites outside the ED achieve this level or better.⁵  The fast-paced work environment of the ED, and patient-centered desire to avoid a “second stick,” has led to the practice in some EDs of using initial intravenous access for blood draws, but this practice, among others, contributes to higher hemolysis rates. Laboratory medicine has identified ED hemolysis as a significant quality issue owing to its impact on efficiency. Unfortunately, the national scope of hemolysis on ED patients is unknown and of utmost importance amidst a policy environment inundated with quality metrics and targets seeking evidence to prioritize process improvement initiatives that can improve outcomes and reduce costs.

To elucidate the impact of hemolysis, we extrapolated data from the 2011 database of the National Hospital Ambulatory Medical Care Survey. Using these data, we applied the hemolysis rate among samples obtained in the ED with which we are affiliated, as well as minimum and maximum values from published reports, to estimate the number of samples affected by hemolysis nationally (Table).

In 2011, among an estimated 136 million ED visits, 57 million visits (42%) included blood tests. More than 30 million samples were tested for electrolytes (23% of all visits). Based on these data, each 1% increase in hemolysis nationally is associated with 300 000 blood tests. Stated otherwise, if national ED hemolysis rates were reduced from 18% to the 2% benchmark, we could eliminate 4 900 000 hemolyzed samples.

Hemolyzed ED blood samples result in substantial technical and facility burden for health care personnel (nurses, technicians, and laboratory personnel) and generate meaningful discomfort and delays in patient care. Further studies are needed to identify preanalytic factors that contribute to hemolysis so that process improvement programs can be implemented to improve quality and efficiency in collecting blood samples in the ED.