Objective: Preterm labor is a common obstetric complication.
Clinical evaluation of cervical ripening to predict
preterm labor has a substantial inter- and intraobserver
variability. We used frequency domain near-infrared
spectroscopy (FD-NIRS) to non-invasively investigate the
changes of the optical properties (i.e., absorption and
scattering of light) in the uterine cervix during druginduced cervical ripening.
Methods: Ten volunteers scheduled for abortion were examined. Optical properties of the uterine cervix were
measured and physiological parameters were calculated
prior to and after induction of cervical ripening using
topical misoprostol. Mean relative changes, standard
error of the mean as well as statistical significance using
the t-test were calculated for oxy- and deoxyhemoglobin,
total hemoglobin, oxygen-saturation, and water. The wavelength-dependent decrease of scattering (scatter power)
was calculated by an exponential fit and tested with the
Results: Misoprostol induced a decrease in total hemoglobin
of 21+/-6% (P<0.05), a decrease in oxyhemoglobin of
22+/-6% (P<0.05), a decrease in deoxyhemoglobin of
16+/-11% and an increase of 368% (P<0.005) in water
content. The scatter power was significantly lower
(P<0.05) after cervical ripening.
Conclusion: Our results show that FD-NIRS is a promising
diagnostic tool to detect changes in cervical concentrations
of hemoglobin and water. A severe tissue edema, probably due to a hormone-induced inflammatory process, seems to be important for cervical ripening. The reduction in total hemoglobin is likely to be a consequence of the increased water content of the tissue resulting in a dramatic increase of the distance between vessels. We propose this technology to assess the cervical ripening and
eventually to predict preterm labor. Lasers Surg. Med.