The role of microwave radiation in reducing formaldehyde fixation times demonstrated in liver

Turnaround time is an important consideration in surgical pathology. The critical step in processing, formaldehyde fixation, is the longest single step. Attempts to shorten the process either by underfixation or by heating have not been satisfactory primarily because the resulting poor-quality fixation impairs immunohistochemistry. The current study evaluated the quality of microwave radiation as an energy source when the fixation time is shortened. Electron micrographs, immunohistochemistry, and hematoxylin and eosinstained paraffin sections were used to evaluate fixation quality relative to the standard 24-h fixation time. By optimizing and controlling the processing variables temperature and wattage during microwave irradiation, we demonstrated that microwave radiation energy alone can reduce fixation times to as little as 20 min while maintaining the quality as judged by ultrastructural, immunohistochemistry, and hematoxylin and eosin criteria.