Vaginal Ultrasound Cerclage Trial

阴道超声环扎术试验是一项多中心、随机临床试验，旨在确定环扎术（在子宫颈周围进行荷包缝合）预防妊娠35周前自发性早产的有效性。我们建议研究具有复发性自发性早产显著风险的妇女（在妊娠17-32周时有过自发性早产的妇女），以及根据中期超声检查发现宫颈长度<25 mm的妇女风险增加的妇女。 一个由7个围产期中心组成的联盟，因其在开展临床试验方面的专业知识而在全国范围内得到认可，将确定约1000名妊娠17-32周时有自发性早产史的妇女。这些妇女将在16-18周开始接受每两周一次的阴道超声检查，并在22周结束。 根据我们的试点数据，这些女性中大约有三分之一的子宫颈<25 mm，有资格随机接受环扎或不接受环扎（对照组）。本试验的拟定疗效和样本量基于文献中的许多报告，特别是来自多中心NICHD孕产妇胎儿医学单位网络的阴道超声数据的两项前瞻性观察性研究。 具体目标如下：1。通过连续的中期妊娠阴道超声评估，确定宫颈环扎术是否能减少有早期自发性早产史且宫颈长度<25 mm的妇女在妊娠35周前的自发性分娩。2.确定在目标1中描述的患者人群中妊娠16-22周时宫颈环扎术的安全性。3.（辅助目的）测量阴道pH值并进行阴道植物群的革兰氏染色，并收集和储存母体血清和宫颈阴道液，用于随后分析所选标记物以预测早产，以便： A.将这些标志物与环扎术的成功或失败相关联 B。进一步明确早期自发性早产的可能机制。

The Vaginal Ultrasound Cerclage Trial is a multicenter, randomized clinical trial, designed to determine the efficacy of cerclage (a purse- string suture placed around the uterine cervix) for the prevention of spontaneous preterm birth prior to 35 weeks' gestation. We propose to study women at significant risk for recurrent spontaneous preterm birth (those with a prior spontaneous birth at 17-32 weeks' gestation) and who also have an increased risk based on midtrimester ultrasonographic findings of a cervical length <25mm. A consortium of 7 perinatal centers, recognized nationally for their expertise in the conduct of clinical trials, will identify approximately 1000 women with a history of a spontaneous preterm birth at 17-32 weeks' gestation. These women will undergo biweekly vaginal sonography beginning at 16-18 weeks, and ending by 22 weeks. Based on our pilot data, approximately one- third of these women will either have or develop a cervix <25mm and be eligible for randomization to cerclage or no cerclage (control group). The proposed efficacy and sample size for this trial is based on many reports in the literature and particularly on two prospective observational studies of vaginal ultrasonographic data from the multicenter NICHD Maternal Fetal Medicine Units Network. The following specific aims will be addressed: 1. To determine if placement of a cervical cerclage reduces spontaneous birth prior to 35 weeks' gestation in women with a prior early spontaneous preterm birth and with a cervix <25mm in length, as determined by serial midtrimester vaginal sonographic evaluation. 2. To determine the safety of cervical cerclage placement at 16-22 weeks' gestation in the patient population described in Aim#1. 3. (Ancillary Aim) To measure vaginal pH and perform Gram stains of vaginal flora and to collect and store maternal serum and cervicovaginal fluid for later analysis of selected markers to predict preterm delivery in order to: A. correlate these markers with the success of failure of cerclage B. further define possible mechanisms of early spontaneous preterm birth.