剖宫产瘢痕妊娠诊断与治疗共识（指南速递SOGC临床实践指南）
剖宫产瘢痕妊娠诊断与治疗共识（指南速递SOGC临床实践指南）相反，对VBAC成功有负面影响的因素包括：孕产妇年龄的增加、高BMI（>30 kg/m 2），难产史，引产，分娩时孕周>40周，出生体重>4000g。产妇年龄较大（> 35岁）更有可能TOLAC后重复剖宫产分娩（OR 1.14; 95% CI 1.03−1.25）[30]。Landon等人指出孕前BMI> 30的孕产妇经阴道分娩的可能性明显低于孕前BMI正常的孕产妇（OR 0.55; 95% CI 0.51−0.60 P < 0.001）[27]。在同一项研究中，BMI> 30的孕产妇VBAC成功率为68.4％，而正常体重孕产妇VBAC成功率为79.6％（P < 0.001）。当综合多种因素（BMI>30，引产，既往无阴道分娩史），VBAC仅发生在44.2％的病例中[27]。2. 减少VBAC成功的因素（表3）据报道，VBAC成功率于
译者：汪文雁 陈琼 张茜 田迪雅 厦门大学附属成功医院（解放军陆军第七十三集团军医院）
审校：郑剑兰 厦门大学附属成功医院（解放军陆军第七十三集团军医院）
接上文：指南速递 | SOGC临床实践指南 NO.382 剖宫产术后再次妊娠阴道试产（一）
影响VBAC成功的因素
据报道，VBAC成功率于50%-85%之间[10 12 21-25]，一项来自加拿大的研究指出，VBAC总体成功率可达76.6%[26]。有很多产前产时变量和孕产妇的组合，以及产科、胎儿因素影响着VBAC的成功率。
1.促进VBAC成功的因素（表2）
孕产妇及产科因素与VBAC可能性较高密切相关，包括白种人、阴道分娩史、前次剖宫产指征不复发，如前次剖宫产进入分娩室时表现为先露异常、自然临产、宫颈成熟、Bishop评分高[27 28]。多变量回归分析确定了与较高VBAC成功率相关的独立因素：白种人（OR 1.8; 95% CI 1.6−1.9），阴道分娩史（OR 3.9; 95 % CI 3.6−4.3），前次不复发的剖宫产指征，如先露异常（OR 1.9; 95% CI 1.0−3.7）[29]，妊娠期高血压疾病（OR 2.3; 95% Cl 1.0−5.8）[29]，无难产史（OR 1.7; 95 % CI 1.5−1.8）[27]。产时因素与VBAC可能性较高密切相关，包括自然临产（OR 1.6; 95 % CI 1.5−1.8），入院时宫颈扩张≥4cm，硬膜外麻醉的使用，分娩时孕周<40周，以及出生体重<4000g（OR 2.0; 95% CI 1.8−2.3）[27 28]。无需使用催产素自然临产的孕产妇成功阴道分娩率为80.6%，需引产的为67.4%，而她们中73.9%需催产素催生（P < 0.001）。
2. 减少VBAC成功的因素（表3）
相反，对VBAC成功有负面影响的因素包括：孕产妇年龄的增加、高BMI（>30 kg/m 2），难产史，引产，分娩时孕周>40周，出生体重>4000g。产妇年龄较大（> 35岁）更有可能TOLAC后重复剖宫产分娩（OR 1.14; 95% CI 1.03−1.25）[30]。Landon等人指出孕前BMI> 30的孕产妇经阴道分娩的可能性明显低于孕前BMI正常的孕产妇（OR 0.55; 95% CI 0.51−0.60 P < 0.001）[27]。在同一项研究中，BMI> 30的孕产妇VBAC成功率为68.4％，而正常体重孕产妇VBAC成功率为79.6％（P < 0.001）。当综合多种因素（BMI>30，引产，既往无阴道分娩史），VBAC仅发生在44.2％的病例中[27]。
当前次剖宫产指征为难产、产程停滞或头盆不称时，一些研究发现VBAC的成功率相差不大[31 32]，尽管更多的研究一致报道VBAC成功率较低[12 22 29 33]。同样，大多数关于引产和VBAC的研究一致认为，与自然临产(74.1%)相比，引产后的阴道分娩率较低（66.3％）（OR 0.66; 95% CI 0.55−0.80）[34]。
不管是自然临产还是引产，妊娠40周后的孕产妇有更高的TOLAC后剖宫产分娩率。孕周≤40周自然临床者，在阴道试产后的剖宫产率为25％，而>40周的则为33.5％（P = 0.001; adjusted OR1.5; CI 1.2−1.8）。同样的引产术后阴道试产，孕周≤40周的剖宫产率为33.8％，而>40周的为43％（P = 0.03; adjusted OR 1.5; CI 1.1−2.2）[35]。
多项研究一致表明，新生儿出生体重> 4000 g的孕产妇VBAC成功率较低。Zelop等研究365名TOLAC后分娩新生儿体重>4000g的孕产妇，指出阴道分娩成功率60％，且母婴发病率及子宫破裂风险没有增加[36]。这些数据支持以前Flamm等（成功率58%）[37]和Sarno等（成功率67%）[38]的研究结果。Elkousy等2003年报道了9960名有剖宫产史计划阴道试产的孕产妇的研究[39]。该研究按新生儿出生体重和生育史（主要是有否阴道分娩史，以及阴道分娩是在剖宫产之前或之后）进一步分层[39]。研究结果表明，VBAC的成功随着出生体重的增加而降低，而从未成功阴道分娩的孕产妇则最低[36 39]。妊娠期子痫前期也与较低的VBAC成功率相关[40]。
3.既往阴道分娩史
既往阴道分娩史是导致VBAC的单个最重要的独立预测因素。有阴道分娩史的孕产妇VBAC成功率高达86.7％，而没有阴道分娩史的孕产妇VBAC成功率为60.9％（OR 4.2; 95% CI 3.8−4.5 P < 0.001）[27]。有阴道分娩史和VBAC史的孕产妇VBAC成功率最高（分别是86.7% 和89.6%）。随着有VBAC史的数量不断增加，妊娠期VBAC成功率也随之增加：对于那些具有0 1 2 3和4或更多VBAC史的孕产妇，VBAC成功率为63.3% 87.6% 90.9% 90.6%和91.6%[41]。
建议
1. 如果没有禁忌症，应在适当讨论和记录母婴风险和益处后，对所有1次子宫下段横切口剖宫产术的孕产妇提供剖宫产术后再次妊娠阴道试产（TOLAC）。讨论应记录在案（II-2B）。
2. 没有分娩禁忌证、有阴道分娩史、和/或已自然临床的孕产妇是TOLAC的最佳人选，并且VBAC成功率较高，应建议她们TOLAC（II-2B）。
3.有负面因素影响VBAC成功的孕产妇也可以TOLAC。然而，应该告知她们VBAC成功率较低，并且并发症和重复剖宫产的风险增加（II-2A）。
预测模型
TOLAC并成功阴道分娩的孕产妇并发症最少。具有最严重不良后果风险的情况是TOLAC后剖宫产。因此，当选择预期的分娩方式时，讨论VBAC的可能性就很重要。
孕产妇TOLAC后VBAC的可能性取决于她的生育史，产前因素和产时因素的特定组合。美国已用产前可确定的因素开发了1次剖宫产史的单胎足月妊娠成功TOLAC的预测模型[43]。该预测模型已在加拿大等其他国家的人群中得到验证[44-48]。该模型可以合理评估VBAC的可能性，并且可在实践中作为一种工具，还可以在产前访视时完善有剖宫产史的孕产妇的咨询并共同决策。其他预测模型也可用，大多数VBAC的预测值较高，范围从88％到95％。但值得注意的重要事项是，这些模型大多数在预测TOLAC不成功的方面都很差，预测值较低，介于33％到58％之间[49]。（与VBAC计算器工具的链接：https://mfmu.bsc.gwu.edu/pub-licbsc/mfmu/vgbirthcal/vagbirth.html）
与TOLAC和ERCS相关的风险
有剖宫产史的符合条件的孕产妇面临着TOLAC或ERCS的选择。计划TOLAC的入选者是孕产妇本人和医疗保健工作者都能接受的VBAC的风险和机会之间的平衡。重要的是要记住，这种风险和益处的平衡是因不同孕产妇而异的[7]。
如果没有TOLAC禁忌，需告知孕产妇两种分娩方式的风险与益处。理想情况下，这些在妊娠早期就提出和讨论的，因此孕产妇有尽可能多的机会探索这两种分娩方式。孕产妇需要了解每种分娩方式的风险与益处及其可能的影响，以便有计划的对TOLAC与ERCS做出明智的决定。
本节提供的重要证据主要来自最近的系统评价[28]和出版的国家指南[7 8 50]。Guise等（2010年）汇总了有关母婴结局的最大数据的研究及样本量[28]。本综述纳入的所有研究均为观察性队列研究，所有的报告结果均基于实际的分娩途径。
加拿大最近一项较大的观察性研究报告了197 540名单胎、妊娠37至43周孕产妇的数据，她们在2003年至2014年间均有1次剖宫产手术[3]。这些结果反映了加拿大背景下更与时俱进的产科实践[3]。值得注意的是，在讨论风险与益处时，证据由于原因多样而受到限制。首先，没有比较计划ERCS和TOLAC的随机研究。大多数信息来源都是观察性研究。其次，大多数研究报告结果都是基于实际的分娩途径而非预期分娩计划。这可能导致对孕产妇的错误分类，以及评估每个计划分娩途径的实际风险过度或低估。第三，这些研究中的定义及报告结果不同。
最后，重要的是要记住，尽管综合估算试图量化与ERCS和TOLAC相关的风险程度，但孕产妇和医疗工作者对这些风险和分娩方式的态度有很大差别。适合某一孕产妇的风险和利益衡量对另一名孕产妇来说可能是不能接受的。重要的是应提供与每个孕产妇及其情况相关的个性化咨询。
TOLAC为孕产妇提供了阴道分娩的机会。如果一名孕产妇TOLAC后VBAC，则综合风险更低，并且避免了与手术和剖宫产术相关的风险。然而，TOLAC有25％紧急剖宫产的发生率，0.5％导致子宫破裂，增加围产期的发病率和死亡率。
ERCS有许多潜在的好处。其中包括可计划、能安排时间、避免与临产和阴道分娩相关的典型风险（如会阴撕裂，盆底损伤），以及避免紧急剖宫产。
孕产妇结局
主要的孕产妇发病率和死亡率包括子宫破裂，出血，血栓栓塞，感染和孕产妇死亡。
孕产妇死亡
在加拿大最大的研究之一，调查1988年至2000年间的有1次剖宫产史的308755名孕产妇的子宫破裂率和死亡率[51]，作者得出结论，虽然TOLAC的子宫破裂率、输血率和子宫切除率较高，但孕产妇的死亡率较低（1.6 / 100 000），比ERCS（5.6 / 100 000）低（校正OR 0.32;95% CI 0.07−1.47）。其他用大型国家围产期数据库的研究也支持这一发现[52 53]。同样地，Guise等分析12份报告中的孕产妇死亡风险，ERCS（13.4 / 100 000）比TOLAC（3.8/ 100 000）显著增加（RR 0.33; 95%CI 0.13−0.88）[28]。当仅分析4项TOLAC和ERCS的孕产妇死亡率均较低的研究时，TOLAC的孕产妇死亡风险（1.9 / 100 000）显着低于ERCS的（9.6 / 100 000）（RR 0.27; 95% CI 0.09−0.85）。
Young等最近的研究报道了在2003年至2014年间加拿大的更多同期的ERCS和VBAC的数据[3]。然而，它并没有将孕产妇死亡作为独立结果，仅将其作为孕产妇死亡率和发病率的一部分进行报告。
总之，无论是TOLAC还是ERCS，孕产妇死亡的绝对风险都很低（表4）。根据加拿大大型研究[51]和系统回顾评价 [28]，与TOLAC相关的孕产妇死亡绝对风险为1.6-3.8 /100 000，与ERCS相关的相对风险为5.6-13.4/100 000。
子宫破裂
已发表许多关于子宫破裂和/或裂开的研究。Guise等纳入8项质量较好或公正的队列研究，包括感兴趣的人群，并使用预先解剖学定义子宫破裂[28]。无论分娩方式如何，所有有剖宫产史的孕产妇的子宫破裂风险均为0.3％（95% CI 0.2−0.4）。经历TOLAC的孕产妇子宫破裂的风险显着升高，为4.7/1000或0.47％（95% CI 0.28−0.77），而ERCS的为0.26 /1000或0.026%（95% CI 0.009−0.082）（RR 20.74;95% CI 9.77−44.02）。加拿大最新的数据表明，TOLAC子宫破裂（包括裂开）的绝对率（9.93 /1000或0.99%）比ERCS（1.75 /1000或0.17%）更高[3]。然而，当仅研究没有裂开的子宫破裂时，其风险类似于系统回顾报道的TOLAC和ERCS的风险（3.3/1000 vs 0.50/1000），经历TOLAC的孕产妇的子宫破裂风险仍然显着的高（aRR 6.41; 95% CI 4.84−8.30）[3]。考虑这两项研究[28]，注意到Guise等包括20世纪90年代到2000年初的研究的系统回顾，Young等的最大加拿大研究则反映了更多最近的产科实践[3]，大部分孕产妇有剖宫产史，尝试TOLAC后子宫破裂的基线风险为0.47％。
在大型系统综述中包括的8项研究中，没有任何因子宫破裂导致的孕产妇死亡的病例。子宫破裂导致的子宫切除风险从14％到33％之间[28]。
其他孕产妇结局
在Guise等报告的大多数其他孕产妇结局中[28]，计划的TOLAC和ERCS之间在出血、子宫切除和感染率方面没有统计学上的显着差异。与TOLAC相比，ERCS有增加子宫内膜炎的趋势; 相反，与ERCS相比，TOLAC有增加绒毛膜羊膜炎的趋势。在TOLAC孕产妇中，BMI的增加与发热的增加相关[28]。Young等报告了孕产妇总体的严重发病率和死亡率，并支持之前观察到TOLAC的孕产妇风险增加（aRR 1.96; 95% CI 1.76−2.19），但ERCS（5.65/1000）和TOLAC（10.7 /1000）的严重孕产妇死亡率和发病率的绝对风险仍然很低[3]。当孕产妇死亡率和发病率被限制为排除输血所致时，TOLAC后成功阴道分娩的风险较低（aRR 0.57; 95% CI 0.45−0.73），而在TOLAC后剖宫产的孕产妇死亡率和发病率的风险比ERCS增加了一倍以上（aRR 2.58; 95% CI 2.25−2.95）[3]。
总之，一次剖宫产史的孕产妇发生不良结局的绝对风险很低。然而，对选择TOLAC的孕产妇认真警惕并严密监测是至关重要的，因为与ERCS相比，TOLAC具有明显更高的子宫破裂风险和复合严重的孕产妇发病率和死亡率。
建议
4. 应告知孕产妇，ERCS孕产妇死亡的相对风险较高，TOLAC子宫破裂和复合严重的孕产妇发病率的风险较高，但这些结局的绝对风险均较低（II-2B）。
5. 应告知一次子宫下段横切口剖宫产史的孕产妇，TOLAC子宫破裂的基线风险为0.47％（II-2A）。
6. 应告知孕产妇，ERCS和TOLAC之间的大多数其他孕产妇并发症没有显着差异（II-2B）。
子宫破裂的危险因素
有许多变量会影响VBAC成功率和子宫破裂风险。大多数研究采用回归分析来更好地评估个体变量的影响然而，每个变量的实际影响程度仍然不确定。更重要的是，常同时发挥作用的多因素综合影响更加不确定。
增加子宫破裂风险的因素
引产与促宫颈成熟药物
使用催产素催生或引产
2次及以上的剖宫产史
短期受孕，分娩间隔<18个月
子宫下段较薄
古典式或子宫下段纵切口
引产
既往剖宫产史的孕产妇可能因各种原因需要提前分娩。对于那些有TOLAC计划的孕产妇来说，引产术并不是禁忌证；然而，了解引产对她们VBAC成功的潜在影响非常重要。更重要的是，必须讨论与特定引产和促宫颈成熟方法相关的子宫破裂风险。
包括Guise等的综述在内的研究表明，无论采用何种引产方法，与自然临产的分娩相比，既往剖宫产史的孕产妇引产后的VBAC成功率始终较低[34]。不论使用何种引产方法，将使VBAC的综合评估值范围为63％（95%可信区间58%−67%）[28]至66.3％[34] ，和较高的重复剖宫产率（OR 1.52; 95 % CI 1.26−1.83）[34]。
相比于自然临产，期待治疗或ERCS，既往剖宫产并接受引产的孕产妇子宫破裂风险也不断增加[28 54]。Guise等报道，考虑任何孕周，任何引产方法，足月妊娠子宫破裂总的风险分别为1.5％和1.0％[28]。妊娠40周以上的孕产妇，引产后子宫破裂的风险似乎更高（3.2％）[28]。同样，Palatnik等与期待治疗相比，引产后的子宫破裂风险显着增高（1.4％ vs 0.5％; aOR 2.73; 95％CI 1.22-6.12）[54]。
不论是人工破膜引产或宫颈已成熟的缩宫素引产，VBAC成功率似乎与自然临产的相似（74%）[55]。那些使用前列腺素或Foley导管促宫颈成熟的孕产妇VBAC成功率较低（57%）。经历引产的孕产妇子宫破裂风险在0.7％到2.7％之间。可能更重要的是要注意，子宫破裂的风险是根据引产方式的不同而有所不同。在大多数情况下会使用多种引产方法，故不能将所得结论推广到所有引产方法中。
引产方式
Cochrane有一篇有关TOLAC各种引产方法的综述，针对剖宫产术后再次妊娠需要引产的孕产妇，纳入了总共只有707名[56]的8项随机试验，比较了妊娠晚期使用安慰剂/无治疗或其他方法促宫颈成熟和引产的。由于研究的不纯一性，无法进行荟萃分析。值得注意是，目前这些小样本和说服力不大的个体随机研究的证据非常有限。
使用观察性研究虽然有限，但目前提供了最好的证据，以告知我们实施VBAC的有效性以及有剖宫产史孕产妇中不同引产方法的潜在风险。Guise等报告，催产素引起子宫破裂的风险最低，为1.1％，其次是PGE 2，为2％，米索前列醇引起子宫破裂的风险最高，为6％[28]。与试产及采用各种引产方法（14 项中等质量研究 12659名孕产妇）相关的子宫破裂的总体评估风险为1.2％（95% CI 0.9%−1.6%）。对于妊娠超过40周TOLAC的孕产妇，每种引产方式（所有方法）似乎都会造成伤害[56]。然而，鉴于研究设计和方法的不一致，这些风险评估可能是不精确的，应谨慎解释结果[28 57]。
方法：机械
Guise等综述了5项低至中等质量、采用机械性引产的小型研究[28]。在其中2项质量较好的研究中，分析4127名使用Foley导管引产的孕产妇，综合评估VBAC成功率为54％（95% CI 49%−59%）[58 59]。最近的两篇报道指出，使用球囊导管促宫颈成熟的VBAC成功率相似（56％-58％）[60-61]。许多研究报告都没有子宫破裂的病例，表明在TOLAC的孕产妇使用球囊导管（不使用其他诱导剂）似乎不比自然临产者增加子宫破裂的风险。然而，这些研究可能样本太小而无法确定子宫破裂的风险。
方法：催产素
关于催产素使用的研究令人困惑的事实是，一些研究仅纳入催产素引产，而其他研究包括催产素催生。根据5项仅纳入催产素引产的研究（不包括催生），VBAC的综合评估值为62％（95% CI53%−70%）[62-66]。当分析仅包括催产素催生的其他6项研究数据时，汇总的VBAC成功率为68％（95％CI 64％-72％）[62-64 67-69]。在这些质量不高的研究中，与催产素引产相比，当使用催产素催生时，似乎可改善VBAC成功率的趋势。在用催产素引产或催生后，子宫破裂的总体风险评估值是基线风险的两倍（1.1％; 95％CI 0.9％-1.5％）[26]。
方法：前列腺素E 2
Guise等的综述中纳入了19项研究[28]。当将具有相似设计的研究结合起来时，采用PGE2引产的TOLAC孕产妇，综合评估VBAC成功率为63％（95％CI 58％-69％）。汇总分析用PGE 2引产后子宫破裂的发生率， 点的评估值为2.0％（95％CI 1.1％-3.5％）。
方法：米索前列醇
米索前列醇被认为是有效且经济的促宫颈成熟和引产药物[70]。虽然使用米索前列醇后VBAC成功率与其他促宫颈成熟剂相似，综合评估值为61％（95% CI 27%−90%）[28]，但这是基于非常小的研究。米索前列醇也会显著增加既往剖宫产史的孕产妇子宫破裂的风险。几个小型系列报道，在TOLAC孕产妇中，使用米索前列醇后子宫破裂的风险为0％至11.7％[71-75]。Blanchette等在TOLAC引产的孕产妇中，比较PGE 2与米索前列醇，发现它们同样有效，但米索前列醇与较高的子宫破裂发生率相关（18.8％，与PGE 2组无破裂相比）[76]。所有这些研究中的样本量都很小，很难得出有意义的结论。在进一步的随机研究完成之前，不建议推荐米索前列醇为有剖宫产史的足月孕产妇的引产或促宫颈成熟的方法[76 77]。
建议
7.引产不是TOLAC孕产妇的禁忌证（II-2A）。
8.应告知孕产妇，引产与剖宫产后阴道分娩率降低和子宫破裂风险增加有关，应在适当咨询后慎重使用。在妊娠40周以上的孕产妇中，引产后子宫破裂的风险似乎是最高的（II-2A）。
9. Foley导管可用于计划性TOLAC孕产妇的促宫颈成熟（II-2B）。
10.使用催产素进行引产或催生不是TOLAC孕产妇的禁忌。然而，使用催产素会增加子宫破裂的风险，应在适当的咨询后慎重使用（II-2B）。
11. 使用前列腺素E2（地诺前列酮）进行药物引产与子宫破裂的风险增加相关，并且在适当的咨询后不推荐TOLAC的孕产妇使用（II-2B）。
12. 前列腺素E1（米索前列醇）与子宫破裂的高风险相关，不应用于足月TOLAC的孕产妇。
专家简介
郑剑兰
郑剑兰，主任医师，教授，研究生导师，厦门大学附属成功医院、解放军第七十三集团军医院暨全军计划生育优生优育技术指导中心妇儿科主任，全军妇产科专业委员及产科学组秘书长，南京军区妇产科副主任委员，英国帝国理工大学母婴研究中心签约学者，全球健康中心及美国辛辛那提大学交流学者，中华医学会围产医学分会委员，中国医师协会母胎医学分会委员，中国对外交流促进会妇产科分会委员，中国妇幼保健协会高危妊娠常务委员，中国研究型医院学会孕产期母儿心脏病专业委员会常务委员，福建省围产医学分会委员、优生优育及妇幼保健协会盆底委员会常务委员、骨质疏松及骨矿盐学会委员，厦门市围产医学分会候任主任委员、妇产科副主任委员、产科质控中心副主任，SCI期刊《ANZJOG》 及《JOGR》审稿专家。
妇产科临床工作30多年，擅长妇科腔镜及产科危急重症抢救，近年来主要从事围产医学研究。主编专著2部；发表SCI及国内核心期刊论著20余篇；主持国家自然科学基金面上项目，省市及军队科研项目10项；引进Bakri产后止血球囊和CRB促宫颈成熟及引产球囊；发明Zheng子宫压迫缝合术，第一完成人获国家专利3项，并获军队和福建省、厦门市医疗成果及科技进步奖9项，享受军队一类科技人才岗位津贴，是军队334工程拔尖人才和厦门大学科技创新人才，多次荣立军队二等功及三等功。
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