Interferometric phase microscopy for label-free morphological evaluation of sperm cells

Objective: To compare label-free interferometric phase microscopy (IPM) to label-free and label-based bright-field microscopy (BFM) in evaluating sperm cell morphology. This comparison helps in evaluating the potential of IPM for clinical sperm analysis without staining. Design: Comparison of imaging modalities. Setting: University laboratory. Patient(s): Sperm samples were obtained from healthy sperm donors. Intervention(s): We evaluated 350 sperm cells, using portable IPM and BFM, according to World Health Organization (WHO) criteria. The parameters evaluated were length and width of the sperm head and midpiece; size and width of the acrosome; head, midpiece, and tail configuration; and general normality of the cell. Main Outcome Measure(s): Continuous variables were compared using the Student's t test. Categorical variables were compared with the chi(2) test of independence. Sensitivity and specificity of IPM and label-free BFM were calculated and compared with label-based BFM. Result(s): No statistical differences were found between IPM and label-based BFM in the WHO criteria. In contrast, IPM measurements of head and midpiece width and acrosome area were different from those of label-free BFM. Sensitivity and specificity of IPM were higher than those of label-free BFM for the WHO criteria. Conclusion(s): Label-free IPM can identify sperm cell abnormalities, with an excellent correlation with label-based BFM, and with higher accuracy compared with label-free BFM. Further prospective clinical trials are required to enable IPM as part of clinical sperm selection procedures. (C) 2015 by American Society for Reproductive Medicine.