Predicting Labor Outcomes in Women Attempting VBAC

假设：众所周知， 在试图阴道分娩的妇女中发病率最高 在先前的剖腹产之后（即，VBAC，但“失败”的尝试，并交付 剖腹产正因为如此，几位研究人员开发了评分系统， 系统来预测尝试VBAC的女性的分娩结果。 由于测试特性不足以及临床问题， 这些评分系统，他们还没有得到普遍接受， 产科社区一种新的测试，胎儿骨盆指数（即，FPI， 将胎儿的超声测量与胎儿的X射线测量相结合， 母亲骨盆），已在不同妇女群体的小型研究中进行了测试 剖宫产的高风险（包括尝试VBAC的患者），并且似乎 具有高灵敏度和特异性。 具体目标：本提案有两个具体目标：1）评估敏感性 和胎儿骨盆指数的特异性（其结合了X射线测量的 骨盆与胎儿的超声测量）的成功/失败， 在尝试VBAC的人中进行分娩试验，2）开发临床 确定试验失败高风险患者组的预测指数 在尝试VBAC的女性中，该预测指数可包括 放射学研究（即，胎儿骨盆指数）、临床因素，以及 历史因素。这一临床预测指数将帮助临床医生决定 是否要为有过剖腹产经历的病人提供一次 阴道分娩，基于阴道分娩失败的风险 给那个病人。预测规则的验证将在内部完成， 使用自举方法。 方法：我们提出了一项为期4年的前瞻性研究，以满足本研究的目的。 我们将招募那些有过剖腹产和重新计划的孕妇 在怀孕36到42周之间尝试VBAC。患者将入组 作为2家医院的门诊病人-宾夕法尼亚大学医院 宾夕法尼亚医院入组时的程序将包括 亲自面谈，审查当前怀孕的产前记录， 审查所有以前分娩的医疗记录，以及 超声检查以获得用于计算FPI的测量值。 病人将有她的照顾在她的自由裁量权的其余部分 医生入组受试者将在以下时间点进行X线骨盆测量： 分娩，但在医院，这些措施将结合 基于超声的胎儿测量来计算FPI。我们选择 分娩后进行X线骨盆测量（并计算FPI事后） 因为在怀孕期间直接进行盆腔放射的安全性问题。我们 分析将包括描述性和双变量分析，以及 多变量临床预测指数的发展。该指数将 预测那些试图在任何适应症剖宫产的可能性， VBAC，可能包括历史或临床预测因素以及FPI。 如果预测指标具有较高的敏感性和特异性， 实施可以增加尝试VBAC的妇女人数，减少 VBAC尝试失败的次数，并降低总剖宫产率， 这群女人。

Hypothesis: It is well established that rates of major maternal morbidity are highest among women who undergo an attempt at a vaginal birth after a prior c-section (i.e., VBAC, but "fail" that attempt and are delivered by cesarean. Because of this, several investigators have developed scoring systems to predict the labor outcome of women who are attempting a VBAC. Because of both inadequate test characteristics as well as clinical issues with these scoring systems, they have not gained acceptance in the general obstetrical community. A novel test, the fetal-pelvic index (i.e., FPI which combines ultrasound measures of the fetus with x-ray measurements of the maternal pelvis), has been tested in small studies in various groups of women at high-risk for cesarean (including those attempting a VBAC), and appears to have both high sensitivity and specificity. Specific Aims: This proposal has 2 specific aims: 1) To assess the sensitivity and specificity of the fetal-pelvic index (which combines x-ray measures of the pelvis with ultrasound measurements of the fetus) for the success/failure of a trial of labor among those attempting VBAC, and 2) To develop a clinical predictive index to define groups of patients at high risk for a failed trial of labor among women attempting a VBAC. This predictive index could include radiological studies (i.e., the fetal-pelvic index), clinical factors, and historical factors. This clinical predictive index will help clinicians decide whether or not to offer a patient with a prior cesarean section an attempt at a vaginal delivery, based on the risk of a failed attempt at a vaginal delivery to that patient. Validation of the prediction rule will be done internally, using a bootstrapping approach. Methods: We propose a 4-year prospective study to meet the aims of this study. We will enroll pregnant women who have had a prior cesarean and a re planning on a VBAC attempt between 36 and 42 weeks gestation. Patients will be enrolled as outpatients at 2 hospitals-the Hospital of the University of Pennsylvania and Pennsylvania Hospital. Procedures at the time of enrollment will include an in-person interview, review of the prenatal record from the current pregnancy, review of the medical records from all previous deliveries, as well as an ultrasound examination to obtain measurements for the calculation of the FPI. The patient will have the remainder of her care at the discretion of her physicians. Enrolled subjects will have x-ray pelvimetry performed after delivery, but while in the hospital, and these measures will be combined with the ultrasound-based fetal measurements to calculate the FPI. We have chosen to perform the x-ray pelvimetry after delivery (and calculate the FPI post-hoc) because of safety concerns with direct pelvic radiation during pregnancy. Our analysis will consist of descriptive and bivariate analysis, as well as the development of a multivariable clinical predictive index. This index will predict the likelihood of cesarean for any indication in those attempting a VBAC, and could include historical or clinical predictors, as well as the FPI. If the predictive index has high sensitivity and specificity, its implementation could increase the number of women attempting VBAC, reduce the number of failed VBAC attempts, and reduce the total cesarean section rate in this group of women.