Fluorescence spectroscopy of the cervix: Influence of acetic acid, cervical mucus, and vaginal medications

Background and Objective: Fluorescence spectroscopy has been shown to provi de information useful in the detection of cervical dysplasia. The goal of t his study was to determine if substances found on the cervix such as acetic acid, mucus, and vaginal medications can influence the fluorescence in the spectral region useful for discriminating normal cervical tissue from abno rmal tissue. Study Design/Materials and Methods: Fluorescence spectra were collected at 337 nm excitation from the cervix in vivo both before and after application of acetic acid; the data were analyzed to identify the effects of the acet ic acid on the spectra. Cervical mucus was acquired from patients referred for colposcopy and frozen until measurements were taken. Fluorescence excit ation-emission matrices (EEMs) were measured for the mucus samples. Additio nally, the transmission spectra of mucus were measured to determine if its absorption could influence the fluorescence signal measured from the tissue , EEMs were measured for samples of commonly prescribed vaginal medications , All EEMs were compared to those of cervical biopsies, Results: Acetic acid introduces changes in both the lineshape and intensity of the spectra, On average, the changes are more significant in spectra of abnormal tissue, Cervical mucus was found to have no significant absorptio n bands, but the measured fluorescence was approximately the same order of magnitude as that measured from the cervix in vitro, Most medications exhib ited significant fluorescence in the spectral region of diagnostic interest for the cervix. Conclusions: Acetic acid appears to increase the differences in fluorescenc e emission spectra of normal and pre-cancerous cervical tissues; thus, its use is beneficial, The presence of cervical mucus can possibly interfere wi th the collection of fluorescence spectra for tissue classification. Patien ts should not use vaginal preparations during the 48 hours prior to tissue fluorescence measurements. (C) 1999 Wiley-Liss, Inc.