Environmental impact of pathology laboratories. Sentinel lymph node diagnostic methodologies: a case study

Healthcare services represent a notable source of environmental impact due to their use of energy-intensive equipment, single-use materials, and chemically complex reagents. Within this context, the diagnostic processing of sentinel lymph nodes serves as a representative procedure through which to evaluate surgical pathology laboratory sustainability. This study employs a Life Cycle Assessment approach to quantify and compare the environmental impacts of two widely used sentinel lymph node diagnostic methodologies: histological ultrastaging and a molecular assay based on one-step nucleic acid amplification. The analysis was conducted at a major Italian research hospital using primary data from clinical workflows, supported by the ecoinvent 3.8 database and modeled in SimaPro. Environmental impacts were characterized using the CML baseline method across 11 midpoint categories. A declared unit, based on a statistically derived median sentinel lymph node, enabled standardized comparison of diagnostic procedures across efficiency scenarios. The results demonstrate that the two methodologies differ substantially in their environmental profiles, with each approach presenting distinct strengths and trade-offs. Histological methods involve more extensive multi-step processing and reagent diversity, while molecular workflows are highly dependent on custom single-use plastics and specialized reagents. Sensitivity and uncertainty analyses provide additional insight into the key drivers of impact and the robustness of the model. This work illustrates how methodological choices in pathology can significantly shape environmental performance and underscores the value of integrating life cycle assesment into the assessment of laboratory practices.