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 χ(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.