Could electrohysterography be the solution for external uterine monitoring in obese women?

OBJECTIVE: To evaluate the influence of maternal obesity on the performance of external tocodynamometry and electrohysterography. STUDY DESIGN: In a 2-hour measurement during term labor, uterine contractions were simultaneously measured by electrohysterography, external tocodynamometry, and intra-uterine pressure catheter. The sensitivity was compared between groups based on obesity (non-obese/obese/morbidly obese) or uterine palpation (good/moderate/poor), and was correlated to maternal BMI and abdominal circumference. RESULT: We included 14 morbidly obese, 18 obese, and 20 non-obese women. In morbidly obese women, the median sensitivity was 87.2% (IQR 74-93) by electrohysterography and 45.0% (IQR 36-66) by external tocodynamometry (p < 0.001). The sensitivity of electrohysterography appeared to be non-influenced by obesity category (p = 0.279) and uterine palpation (p = 0.451), while the sensitivity of tocodynamometry decreased significantly (p = 0.005 and p < 0.001, respectively). Furthermore, the sensitivity of both external methods was negatively correlated with obesity parameters, being non-significant for electrohysterography (range p-values 0.057-0.088) and significant for external tocodynamometry (all p-values < 0.001). CONCLUSIONS: Electrohysterography performs significantly better than external tocodynamometry in case of maternal obesity.

Electrohysterography for uterine monitoring during term labour compared to external tocodynamometry and intra-uterine pressure catheter.

OBJECTIVE: Current uterine monitoring techniques have major drawbacks that could be avoided when using electrohysterography for uterine monitoring. Recently, a new electrohysterography method has been developed, providing a real-time tocogram on standard cardiotocography monitors. The diagnostic characteristics of this novel method need to be determined and compared to conventional methods We hypothesised that electrohysterography can perform better than external tocodynamometry due to the adhesive properties of the contact electrodes (less motion sensitive), and the improved signal acquisition through subcutaneous tissue (less obesity sensitive). STUDY DESIGN: In this prospective diagnostic accuracy study, uterine contractions of labouring women were simultaneously monitored by three different monitoring techniques: electrohysterography, external tocodynamometry, and intra-uterine pressure catheter as method of reference. We performed a two-hour measurement during first and/or second stage of term labour. The contractions of each method were automatically detected by a computer-based algorithm. As the applied method had not been described in literature before, an interim analysis was performed to minimise exposure to the invasive pressure catheter. The main outcome parameter was the sensitivity of electrohysterography in comparison to external tocodynamometry for uterine contraction detection, tested by the Wilcoxon signed rank test. RESULTS: Uterine contractions of 48 term labouring women were simultaneously monitored by electrohysterography, external tocodynamometry, and intra-uterine pressure catheter. The study was terminated after the interim analysis as the sensitivity of electrohysterography was significantly higher compared to external tocodynamometry: median 89.5% (interquartile range (IQR); 82-93) and 65.3% (IQR; 53-81) respectively, p<0.001. In a subgroup analysis of obese women (n=15), the sensitivity of electrohysterography was significantly higher than external tocodynamometry (median 88.4% (IQR; 79-95) and 45.8% (IQR; 38-61) respectively, p<0.001). Whereas in a subanalysis of second stage of labour (n=8), electrohysterography did not perform better than external tocodynamometry (median 72.8% (IQR; 61-87) and 66.4% (IQR; 46-75) respectively, p=0.225). Electrohysterography registered 0.4 more contractions per 10min than the intra-uterine pressure measurement (p<0.001) and 0.5 more contractions per 10min than external tocodynamometry (p<0.001). CONCLUSION: Electrohysterography has a higher sensitivity for uterine contraction detection than external tocodynamometry during first stage of labour, in non-obese and obese women. Electrohysterography identifies more contractions than conventional techniques.

Toward a new modality for detecting a uterine rupture: electrohysterogram propagation analysis during trial of labor after cesarean.

OBJECTIVE: Observational cohort study which aimed to explore the potential of electrohysterogram (EHG) analysis for detecting a uterine rupture during trial of labor after cesarean. The EHG propagation characteristics surrounding the uterine scar of six patients with a previous cesarean section were compared to a control group of five patients without a scarred uterus. METHODS: The EHG was recorded during the first stage of labor using a high-resolution 64-channel electrode grid positioned on the maternal abdomen across the cesarean scar. Based on simulations, the inter-channel correlation and propagation direction were adopted as EHG parameters for evaluating possible disruption of electrical propagation by the uterine scar. RESULTS: No significant differences in inter-channel correlation or propagation direction were observed between the group of patients with an intact uterine scar and the control group. A strong predominance of vertical propagation was observed in one case, in which scar rupture occurred. CONCLUSIONS: The results support unaffected propagation of electrical activity through the intact uterine scar tissue suggesting that changes in the EHG might only occur in case of rupture.