Guise Jeanne-Marie, Eden Karen, Emeis Cathy, Denman Mary Anna, Marshall Nicole, Fu Rongwei Rochelle, Janik Rosalind, Nygren Peggy, Walker Miranda, McDonagh Marian
Evid Rep Technol Assess (Full Rep). 2010 Mar(191):1-397.
To synthesize the published literature on vaginal birth after cesarean (VBAC). Specifically, to review the trends and incidence of VBAC, maternal benefits and harms, infant benefits and harms, relevant factors influencing each, and the directions for future research.
Relevant studies were identified from multiple searches of MEDLINE; DARE; the Cochrane databases (1966 to September 2009); and from recent systematic reviews, reference lists, reviews, editorials, Web sites, and experts.
Specific inclusion and exclusion criteria were developed to determine study eligibility. The target population includes healthy women of reproductive age, with a singleton gestation, in the U.S. with a prior cesarean who are eligible for a trial of labor (TOL) or elective repeat cesarean delivery (ERCD). All eligible studies were quality rated and data were extracted from good or fair quality studies, entered into tables, summarized descriptively and, when appropriate, pooled for analysis. The primary focus of the report was term pregnancies. However, due to a small number of studies on term pregnancies, general population studies including all gestational ages (GA) were included in appropriate areas.
We identified 3,134 citations and reviewed 963 papers for inclusion, of which 203 papers met inclusion and were quality rated. Studies of maternal and infant outcomes reported data based upon actual rather than intended router of delivery. The range for TOL and VBAC rates was large (28-82 percent and 49-87 percent, respectively) with the highest rates being reported in studies outside of the U.S. Predictors of women having a TOL were having a prior vaginal delivery and settings of higher-level care (e.g., tertiary care centers). TOL rates in U.S. studies declined in studies initiated after 1996 from 63 to 47 percent, but the VBAC rate remained unimproved. Hispanic and African American women were less likely than their white counterparts to have a vaginal delivery. Overall rates of maternal harms were low for both TOL and ERCD. While rare for both TOL and ERCD, maternal mortality was significantly increased for ERCD at 13.4 per 100,000 versus 3.8 per 100,000 for TOL. The rates of maternal hysterectomy, hemorrhage, and transfusions did not differ significantly between TOL and ERCD. The rate of uterine rupture for all women with prior cesarean is 3 per 1,000 and the risk was significantly increased with TOL (4.7/1,000 versus 0.3/1,000 ERCD). Six percent of uterine ruptures were associated with perinatal death. No models have been able to accurately predict women who are more likely to deliver by VBAC or to rupture. Women with one prior cesarean delivery and previa had a statistically significant increased risk of adverse events compared with previa patients without a prior cesarean delivery; blood transfusion (15 versus 32.2 percent), hysterectomy (0.7 to 4 percent versus 10 percent), and composite maternal morbidity (15 versus 23-30 percent). Perinatal mortality was significantly increased for TOL at 1.3 per 1,000 versus 0.5 per 1,000 for ERCD. Insufficient data were found on nonmedical factors such as medical liability, economics, hospital staffing, structure and setting, which all appear to be important drivers for VBAC.
Each year 1.5 million childbearing women have cesarean deliveries, and this population continues to increase. This report adds stronger evidence that VBAC is a reasonable and safe choice for the majority of women with prior cesarean. Moreover, there is emerging evidence of serious harms relating to multiple cesareans. Relatively unexamined contextual factors such as medical liability, economics, hospital structure, and staffing may need to be addressed to prioritize VBAC services. There is still no evidence to inform patients, clinicians, or policymakers about the outcomes of intended route of delivery because the evidence is based largely on the actual route of delivery. This inception cohort is the equivalent of intention to treat for randomized controlled trials and this gap in information is critical. A list of future research considerations as prioritized by national experts is also highlighted in this report.
综合已发表的关于剖宫产术后阴道分娩（VBAC）的文献。具体而言，回顾VBAC的趋势和发生率、对母体的益处和危害、对婴儿的益处和危害、影响各方面的相关因素以及未来研究方向。
通过对MEDLINE、DARE、Cochrane数据库（1966年至2009年9月）进行多次检索，以及从近期的系统评价、参考文献列表、综述、社论、网站和专家处获取相关研究。
制定了具体的纳入和排除标准以确定研究的 eligibility。目标人群包括美国健康的育龄单胎妊娠妇女，她们既往有剖宫产史且符合试产（TOL）或择期再次剖宫产（ERCD）条件。对所有符合条件的研究进行质量评级，并从质量良好或中等的研究中提取数据，录入表格，进行描述性总结，并在适当情况下进行汇总分析。报告的主要重点是足月妊娠。然而，由于关于足月妊娠的研究数量较少，在适当领域纳入了包括所有孕周（GA）的一般人群研究。
我们识别出3134条引文并审查了963篇纳入文献，其中203篇符合纳入标准并进行了质量评级。关于母婴结局的研究报告的数据基于实际分娩途径而非预期分娩途径。TOL和VBAC率的范围很大（分别为28% - 82%和49% - 87%），美国以外的研究报告的率最高。进行TOL的女性的预测因素是既往有阴道分娩史以及在高级别护理机构（如三级护理中心）。美国研究中1996年后开展的研究中TOL率从63%降至47%，但VBAC率仍未改善。西班牙裔和非裔美国女性比白人女性进行阴道分娩的可能性更小。TOL和ERCD的总体母体伤害率都较低。虽然TOL和ERCD中均罕见，但ERCD的孕产妇死亡率显著增加，为每10万例中有13.4例，而TOL为每10万例中有3.8例。TOL和ERCD之间的子宫切除术、出血和输血率没有显著差异。所有既往有剖宫产史的女性子宫破裂率为每1000例中有3例，TOL时风险显著增加（4.7/1000对ERCD的0.3/1000）。6%的子宫破裂与围产期死亡相关。没有模型能够准确预测更有可能通过VBAC分娩或发生破裂的女性。与无既往剖宫产史的前置胎盘患者相比，有一次既往剖宫产史且前置胎盘的女性发生不良事件的风险在统计学上显著增加；输血（15%对32.2%）、子宫切除术（0.7%至4%对10%）以及综合母体发病率（15%对23% - 30%）。TOL的围产期死亡率显著增加，为每1000例中有1.3例，而ERCD为每1000例中有0.5例。在医疗责任、经济因素、医院人员配备、结构和环境等非医疗因素方面发现的数据不足，而这些因素似乎都是VBAC的重要驱动因素。
每年有150万育龄妇女进行剖宫产，且这一人群持续增加。本报告提供了更强有力的证据表明，对于大多数既往有剖宫产史的女性而言，VBAC是一种合理且安全的选择。此外，有新出现的证据表明多次剖宫产存在严重危害。可能需要解决相对未被研究的背景因素，如医疗责任、经济因素、医院结构和人员配备等，以便优先提供VBAC服务。由于证据很大程度上基于实际分娩途径，目前仍没有证据为患者、临床医生或政策制定者提供关于预期分娩途径结局的信息。这个初始队列相当于随机对照试验中的意向性治疗，而这一信息差距至关重要。本报告还突出了国家专家确定的未来研究优先考虑事项清单。
