Predicting Labor Outcomes in Women Attempting VBAC

假设：已经确定的是，主要孕产妇死亡率 在尝试阴道分娩的妇女中发病率最高 在前一次剖腹产(即，VBAC，但是尝试失败并交付)之后 剖腹产。正因为如此，几名调查人员已经开发出了评分 用于预测尝试VBAC的妇女的分娩结局的系统。 由于不充分的测试特征以及临床问题， 这些计分系统，他们还没有得到普遍的接受 产科社区。一种新的测试，胎儿盆腔指数(即，FPI 结合胎儿的超声波测量和X-射线测量 母体骨盆)，已经在不同的妇女群体中进行了小型研究测试 剖宫产风险高(包括那些试图进行VBAC的人)，并且似乎 具有较高的敏感性和特异性。 具体目标：本提案有两个具体目标：1)评估敏感性 胎儿盆腔指数的特异性(结合X-射线测量 骨盆和胎儿的超声测量)对一次手术的成功/失败 在尝试VBAC的人中进行分娩试验，以及2)开发临床 用于定义试验失败高危患者群体的预测性指数 在尝试VBAC的妇女中分娩的风险。这一预测性指数可以包括 放射学检查(即胎儿骨盆指数)、临床因素和 历史因素。这一临床预测指标将帮助临床医生决定 是否向有过剖腹产经历的患者提供一种尝试 阴道分娩，基于尝试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，以满足本研究的目标。 我们将招募有剖腹产和重新计划的孕妇。 在怀孕36周到42周之间的VBAC尝试。患者将被招募 作为两家医院的门诊病人-宾夕法尼亚大学医院 和宾夕法尼亚医院。登记时的程序将包括 面谈，回顾这次怀孕的产前记录， 审查以前所有分娩的医疗记录，以及 超声检查，以获得用于计算FPI的测量结果。 病人的其余护理工作由她自行决定。 医生。登记的受试者将在以下时间进行x光骨盆测量 分娩，但在住院期间，这些措施将结合 以超声为基础的胎儿测量来计算胎心指数。我们已经选择了 产后进行X光骨盆测量(并计算产后FPI) 由于怀孕期间直接进行盆腔放射的安全考虑。我们的 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开发。该索引将 预测那些尝试剖腹产的人的任何指征的可能性 VBAC，并可包括历史或临床预测指标，以及FPI。 如果预测指数具有较高的敏感性和特异性，则其 实施可增加尝试VBAC的妇女数量，减少 失败的VBAC尝试次数，并降低 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.