[Electrohysterography, a promising alternative for uterine monitoring: 5 years later]. / Elektrohysterografie veelbelovend alternatief voor weeënregistratie.

Electrohysterography monitors the electrical activity of the uterine muscle through electrodes on the maternal abdominal wall. It is a non-invasive method for uterine contraction monitoring and has a strong correlation with the invasive intra-uterine pressure catheter. A prospective validation study showed a significant higher sensitivity of electrohysterography compared to external tocodynamometry for uterine contraction detection (p-value < 0.001). Moreover, the sensitivity of electrohysterography appears to be less affected by maternal obesity compared to external tocodynamometry. A clinical pilotstudy comparing electrohysterography and external tocodynamometry during labor, showed no negative effect of electrohysterography on labor outcomes. Recently, technical improvements have been made and electrohysterography has become available in an adhesive electrode patch together with fetal and maternal electrocardiography. Therefore, we expect a successful implementation of electrohysterography in the near future.

Uterine Monitoring Techniques from Patients' and Users' Perspectives.

Objective To evaluate preferences from patients and users on 3 uterine monitoring techniques, during labor. Study Design Women in term labor were simultaneously monitored with the intrauterine pressure catheter, the external tocodynamometer, and the electrohysterograph. Postpartum, these women filled out a questionnaire evaluating their preferences and important aspects. Nurses completed a questionnaire evaluating users' preferences. Results Of all 52 participating women, 80.8% preferred the electrohysterograph, 17.3% the intrauterine pressure catheter and 1.9% the external tocodynamometer. For these women, the electrohysterograph scored best regarding application and presence during labor ( p < 0.001). Most important aspects were "least likely to harm" and "least discomfort". Of 57 nurses, 40.4% preferred the electrohysterograph, 35.1% the external tocodynamometer, and 24.6% had no preference, or replied that their preference is subject to situation and patient. Conclusion Patients prefer the electrohysterograph over the external tocodynamometer and the intrauterine pressure catheter, while healthcare providers report ambiguous results.

Clinical Use of Electrohysterography During Term Labor: A Systematic Review on Diagnostic Value, Advantages, and Limitations.

IMPORTANCE: Real-time electrohysterography (EHG)-based technologies have recently become available for uterine monitoring during term labor. Therefore, obstetricians need to be familiar with the diagnostic value, advantages, and limitations of using EHG. OBJECTIVE: The aims of this study were to determine the diagnostic value of EHG in comparison to (1) the intrauterine pressure catheter (IUPC), (2) the external tocodynamometer (TOCO), and (3) in case of maternal obesity; (4) to evaluate EHG from users' and patients' perspectives; and (5) to assess whether EHG can predict labor outcome. EVIDENCE ACQUISITION: A systematic review was performed in the MEDLINE, EMBASE, and Cochrane library in October 2017 resulting in 209 eligible records, of which 20 were included. RESULTS: A high sensitivity for contraction detection was achieved by EHG (range, 86.0%-98.0%), which was significantly better than TOCO (range, 46.0%-73.6%). Electrohysterography also enhanced external monitoring in case of maternal obesity. The contraction frequency detected by EHG was on average 0.3 to 0.9 per 10 minutes higher compared with IUPC, which resulted in a positive predictive value of 78.7% to 92.0%. When comparing EHG tocograms with IUPC traces, an underestimation of the amplitude existed despite that patient-specific EHG amplitudes have been mitigated by amplitude normalization. Obstetricians evaluated EHG tocograms as better interpretable and more adequate than TOCO. Finally, potential EHG parameters that could predict a vaginal delivery were a predominant fundal direction and a lower peak frequency. CONCLUSIONS AND RELEVANCE: Electrohysterography enhances external uterine monitoring of both nonobese and obese women. Obstetricians consider EHG as better interpretable; however, they need to be aware of the higher contraction frequency detected by EHG and of the amplitude mismatch with intrauterine pressure measurements.

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.

Tocogram characteristics of uterine rupture: a systematic review.

PURPOSE: Timely diagnosing a uterine rupture is challenging. Based on the pathophysiology of complete uterine wall separation, changes in uterine activity are expected. The primary objective is to identify tocogram characteristics associated with uterine rupture during trial of labor after cesarean section. The secondary objective is to compare the external tocodynamometer with intrauterine pressure catheters. METHODS: MEDLINE, EMBASE, and the Cochrane library were systematically searched for eligible records. Moreover, clinical guidelines were screened. Studies analyzing tocogram characteristics of uterine rupture during trial of labor after cesarean section were appraised and included by two independent reviewers. Due to heterogeneity, a meta-analysis was only feasible for uterine hyperstimulation. RESULTS: Thirteen studies were included. Three tocogram characteristics were associated with uterine rupture. (1) Hyperstimulation was more frequently observed compared with controls during the delivery (38 versus 21 % and 58 versus 53 %), and in the last 2 h prior to birth (19 versus 4 %). Results of meta-analysis: OR 1.68 (95 % CI 0.97-2.89), p = 0.06. (2) Decrease of uterine activity was observed in 14-40 % and (3) an increasing baseline in 10-20 %. Five studies documented no changes in uterine activity or Montevideo units. A direct comparison between external tocodynamometer and intrauterine pressure catheters was not feasible. CONCLUSIONS: Uterine rupture can be preceded or accompanied by several types of changes in uterine contractility, including hyperstimulation, reduced number of contractions, and increased or reduced baseline of the uterine tonus. While no typical pattern has been repeatedly reported, close follow-up of uterine contractility is advised and hyperstimulation should be prevented.

[A woman with floating spheres in her abdomen]. / Een vrouw met drijvende bolletjes in haar buik.

A 55-year-old postmenopausal woman presented with acute abdominal pain. Ultrasound and MRI revealed a large, unilocular, cystic abdominal mass, with remarkable floating spheres. Histopathology showed a dermoid cyst. This is a benign ovarian neoplasm, which can contain elements of all three germ layers: primarily hair, teeth, skin or sebaceous tissue.

[Electrohysterography. A promising alternative for monitoring contractions]. / Elektrohysterografie. Een veelbelovend alternatief voor weeënregistratie.

Monitoring contractions during labour using the external tocodynamometer can be difficult or even impossible, and using the invasive intrauterine pressure catheter is associated with rare but serious complications. A new non-invasive technique is currently available: electrohysterography (EHG). This technique converts the electrical activity of the uterine muscle into a legible tocogram. The EHG signal has a high correlation with the intra-uterine pressure and provides a more accurate assessment of uterine activity compared to external tocodynamometry. EHG is suitable for women in labour with failure of the external tocodynamometer. In clinical practice EHG also appeared to report a more detailed tocographic waveform, like hypertonia or unorganized electrical uterine activity. However, its signal quality depends on adequate skin preparation and correct positioning of the electrodes on the maternal abdomen. Hence, with electrohysterography as non-invasive alternative for uterine monitoring, choosing between safety and accuracy is no longer necessary.