Domestic microwave versus conventional tissue processing: a quantitative and qualitative analysis

Microwave irradiation has been tried as a replacement for the conventional tissue processing technique in histopathology laboratories for quite some time. Studies have shown that Domestic Microwave Tissue Processing (DMWTP) provides a faster delivery of the tissue sections with a morphology which is similar to that which is seen Conventional Tissue Processing (CTP). But many laboratories still confine the domestic microwave tissue processing method only to the handle selected specimens, for which urgent reports are needed. One of the probable reasons is that, understanding about the number of tissue sections which can be processed using a microwave oven at a time, with the appropriate quality, still remains unclear.

The aim of this study was to quantitatively analyze the optimum number of samples that a domestic microwave could process at a time, as well as to qualitatively analyze the morphological outcome of those tissue sections with that of conventional processing.

This study was approved by the research and ethical committee of Sree Balaji Medical College and Hospital. A total of 135 paired tissue sections were included in the study. Ten tissue sections (which are mentioned hereafter as A10) were processed in a domestic microwave and their paired 10 tissues were processed by a conventional method. Subsequently, the number of tissues which was to be processed was increased to B15, C20, D25, E30 and F35, after ascertaining that the morphological qualities of the previously processed tissue sections were satisfactory. Sections of 4 μm thickness were taken and they were stained by the Haematoxylin and Eosin method. The slides of the tissues which were processed by the microwave method and the conventional method were randomly numbered, for a blind study, which were independently evaluated by two observers. The qualities of slides were assessed, based on 4 parameters: the cytoplasmic details, the nuclear details, the tissue architecture and the staining characteristics. The statistical analysis was done by using SPSS 15.0.

The morphological outcomes (quality) of the DMWTPs were comparable to that of the CTPs, when the sample load (quantity) in the microwave oven was up to 25 samples.

Domestic microwave processing can be effectively used in laboratories with a maximum sample size of 25 samples per load. This has the advantage of being rapid, with its morphological quality being identical to that of conventional processing.