Electrohysterographic estimation of the intra uterine pressure

Electrohysterography (EHG) is a promising technique for monitoring the uterine activity. However, a quantitative estimation of the internal uterine pressure (IUP) by means of EHG is still not available. In this paper we present a method for the estimation of the IUP from abdominal EHG measurements. For the EHG analysis we use two different Time Frequency Distributions (TFD): the spectrogram and the Wigner-Ville Distribution. We assume the EHG to be the sum of frequency modulated signals. Based on this assumption, the IUP is eventually estimated from the unnormalized first moment of the TFD. A recent IUP estimation method based on EHG measurements is employed as a comparison to validate the performance of our algorithm. The algorithms were tested on two patient recordings. The real IUP was measured by an internal catheter and used as a reference. The IUP estimated by our method showed a determination coefficient with the real IUP (R^2= 0.93), higher than the one obtained with the comparison method (R^2= 0.75). Therefore, we may conclude that the proposed method is a promising clinical technique for accurate non-invasive IUP measurement.