Surface-enhanced Raman spectroscopy analysis of menstrual cycle: From biochemical changes to diagnostics of vaginal infections

Analysis of vaginal fluid is essential for the diagnosis of cervical cancer, various infections and the increasingly common infertility as well. Surface-enhanced Raman spectroscopy (SERS), which is an ultrasensitive technique, provides information from the molecular level of the analysed system and together with chemometric methods, can be a perfect diagnostic tool. However, the variety of processes naturally occurring during the menstrual cycle has a definite impact on the biochemistry of vaginal swabs. This study adopted SERS to track the biochemical changes recorded in spectra of analysed clinical entities during two menstrual cycles. Using Partial Least Squares Regression (PLSR) technique, we demonstrated the spectral information typical for three types of body fluid: menstrual blood (MB), menstrual spotting (MS) and vaginal fluid (VF). The hormonal changes during the menstrual cycle can be reflected in SERS spectra and allow distinction between the fertile and infertile phases. Significantly larger data separation was observed due to infection rather than hormonal fluctuation. These results give a firm foundation for the diagnosis of vaginal infections regardless of the menstrual cycle's day.