Improving interpretation of biopsies during microsurgical testicular sperm exploration in azospermic patients: use of Davidson's fluid.

Histological interpretation of testicular biopsies in the investigation of infertility in men with azoospermia requires adequate tissue fixation to preserve the nuclear and cytoplasmic detail, as well as the architectural organisation of germ cells in different phases of maturation within seminiferous tubules. The aim of the study was to assess the histomorphological quality of testicular biopsies using Davidson's fluid (DF) as fixative and compare it to standard 10% neutral buffered formalin. Concurrent testicular biopsies from the same testis from patients undergoing microsurgical testicular sperm exploration (m-TESE) were separately fixed in DF and formalin and processed for histological examination. Histological parameters including sloughing of cells, cytoplasmic shrinkage of seminiferous tubular cells, nuclear chromatin detail, cytoplasmic graininess and overall clarity of morphological detail were graded on a scale of 0-4 (0, none; 1, minimal; 2, slight; 3, moderate; 4, marked). The effect of DF on biopsy diagnoses was assessed by comparison with corresponding formalin fixed biopsy diagnoses. Eighty-seven testicular biopsies from 27 patients were examined. DF fixation resulted in significantly less luminal sloughing of cells (1.59±1.34 vs 3.44±0.83, p≤0.00001), less cytoplasmic shrinkage of seminiferous tubular cells (1.58±1.11 vs 3.11±1.07, p≤0.00001), better nuclear chromatin detail (3.06±0.91 vs 1.92±0.48, p≤0.00001), less cytoplasmic graininess (2.11±0.96 vs 2.86±0.87, p=0.0014) and better overall clarity of morphological detail than formalin fixation (3.14±0.69 vs 2.14±0.58, p≤0.00001). The diagnostic concordance between DF fixed and formalin fixed biopsies was 90.8%. This study supports the use of DF as a superior alternative fixative to formalin for histological assessment of testicular biopsies.