EASI: Shear Wave Elastography Assessment For Predicting Success Of Labor Induction

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Project Summary The most recent data indicate that 1 in 4 pregnant women in the U.S. undergoes induction of labor (IOL), making this one of today's most common obstetrical interventions. Yet it is one of the least predictable with respect to outcome (vaginal vs. cesarean delivery) and one of the least well studied with respect to best practice. The frequency of IOL has increased in recent years, paralleled by an increase in the number of cesarean deliveries. The relationship between IOL and cesarean delivery is not straightforward, but it is clear that both interventions have become significant public health issues because of their associated increased resource utilization and morbidity. Specifically, higher utilization is seen in women who undergo labor induction and cesarean delivery is associated with higher morbidity (immediate and future) for both mother and neonate. Cervical readiness is crucial to IOL success. This is logical since the cervix must open for the baby to deliver. Given this, it is almost unbelievable that today's practitioner relies on a subjective clinical assessment of cervical "favorability" for important decisions about who should undergo IOL or, if delivery is medically indicated, whose cervix needs ripening (softening) before IOL and what type of ripening would be best. To assess cervical favorability, the practitioner assigns points to cervical characteristics such as dilatation, softness, and length as assessed per vaginal exam. The points are combined into a summative Bishop score (BS), which is supposed to predict success of IOL. Practitioners often complain about the subjectivity and lack of reproducibility of the BS, but many do not even know about another significant issue: the BS was developed more than 50 years ago for a purpose that today is no longer relevant. Specifically, it was developed to predict time to delivery in a woman with a history of vaginal delivery at full term gestation in the current pregnancy. This information was eventually leveraged to imply success from IOL in these women. Today we know that the chance of success in such a woman is so high that her cervical exam is almost irrelevant. But the BS is still used on a daily basis in obstetrical practice to predict the chance of vaginal delivery in a woman at any gestational age who has never before had a baby. Unsurprisingly, this re-purposed BS is a poor predictor of IOL success. That said, it certainly makes sense that characteristics such as cervical dilatation and softness would predict how well the cervix will open because these are physical manifestations of underlying biomechanical characteristics that dictate tissue function. Quantitative ultrasound (QUS) techniques can provide objective, measurable information about tissue properties such as softness, which means that they could contribute to a personalized metric to predict approach to, and expectations for, IOL. Toward that end, this proposal describes a prospective, observational, cross-sectional study designed to evaluate whether QUS techniques can improve prediction of IOL success.