Electrohysterogram-based Sensor for Non-Invasive Contraction Monitoring With Improved Reliability

The majority of obstetric deliveries in the US undergo electronic monitoring and continuous uterine activity monitoring is the standard of care. Typically, an external tocodynamometer (strain gauge, toco for short) is employed to provide the frequency and timing of uterine contractions. The reliability of this monitor depends on its proper positioning (which may be disturbed by patient movement), and the transmission of tension from the uterus to the sensor. In some patients, particularly the obese, the monitor may fail to detect contractions consistently. In others the monitor requires frequent repositioning by the nursing staff. The alternative uterine activity monitor is an intrauterine pressure catheter (IUPC), which is placed through the cervical os in the adequately dilated patient with ruptured membranes. While this monitor usually provides a more reliable signal, as well as quantitative information regarding intrauterine pressure, its invasive nature and increased risk of infection limit enthusiasm for its use.

Obesity is an ever-increasing problem in the US, and is even more prominent in the obstetric suite.

Meanwhile, obese women have an increased risk for labor problems, infections and other complications. Noninvasive uterine activity monitoring, while preferable to reduce the infection risk, is particularly unreliable in this population.