前置血管25例临床分析

目的:探讨前置血管的孕期处理及围产儿结局。方法:收集2011年1月至2017年8月在北京大学第三医院分娩的25例前置血管患者的临床资料,回顾性分析其临床特点、孕期处理和围产儿结局。结果:(1)临床特征:25例前置血管患者占同期分娩产妇总数的0.8‰。患者年龄24~44岁,平均32.9±4.9岁。自然受孕20例(80.0%),体外受精-胚胎移植后受孕5例(20.0%);单胎22例(88.0%),双胎3例(12.0%)。孕期超声诊断15例(60.0%)并经分娩后胎盘检查证实,孕期超声检查未提示但分娩时诊断10例(40.0%)。帆状胎盘21例(84.0%),副胎盘4例(16.0%)。(2)孕期监测及处理:孕期超声诊断前置血管的15例患者中,14例于孕28~34周入院给予地塞米松促胎肺成熟,15例中13例因前置血管计划剖宫产分娩,2例因子痫前期、胎膜早破分别于孕34.8周和孕30.4周急诊剖宫产分娩。产时诊断前置血管的10例患者,5例择期剖宫产分娩,分娩孕周38.3~40.0周;4例因瘢痕子宫、先兆临产或胎膜早破、胎盘早剥急诊剖宫产分娩,分娩孕周36.0~39.3周;1例孕36.9周自然分娩。(3)围产儿结局:25例患者分娩活产儿28个,平均出生体质量2737.9±632.2 g。24例剖宫产分娩者均无新生儿窒息。仅1例患者孕36.9周阴道分娩,新生儿重度窒息。结论:孕期进行超声筛查大部分能产前明确前置血管诊断,孕28~32周收住院给予糖皮质激素促胎肺成熟,孕34~37周剖宫产终止妊娠,可获得良好的围产儿结局。     

单胎妊娠帆状胎盘围产儿结局分析

目的:评估单胎妊娠帆状胎盘(VCI)未合并前置血管者的围产儿结局。方法:回顾性队列研究2018年1月至2020年12月于同济大学附属第一妇婴保健院分娩的孕周≥28周的单胎妊娠患者,剔除前置血管、双胎人群后,帆状胎盘组(VCI组)患者332例,未合并帆状胎盘组(非VCI组)患者78577例,分析两组人群的围产儿结局差异。结果:非VCI组的早产率为5.06%,小于胎龄儿(SGA)为4.62%,宫内死胎为0.12%,剖宫产率为42.11%。VCI组的早产率为10.54%,SGA为12.35%,宫内死胎为0.90%,剖宫产率为63.86%。VCI组患者的早产、SGA、宫内死胎、剖宫产率均高于非VCI组(P<0.05)。结论:单胎人群中,未合并前置血管VCI者围产儿小于胎龄儿、早产、宫内死胎风险增加,剖宫产率升高。     

胎儿医学框架下的氯化钾减胎术应用于早中孕期多胎妊娠的经验——来自单一中心的临床研究

目的:总结我院在胎儿医学框架下建立的氯化钾减胎术在早中孕期应用于多胎妊娠的临床经验。方法:回顾研究2011年1月至2013年12月在上海市第一妇婴保健院于孕11~16周行氯化钾减胎的32例患者的临床资料,记录围手术期母胎并发症及分娩28天后围产儿结局,总结单一中心采用该技术积累的相关经验。结果:患者的平均减胎手术孕周(13.81±0.84)周,平均分娩孕周(34.52±5.78)周,平均新生儿出生体重(2541±665.9)g。围产儿存活率为92.8%,母体并发症包括妊娠期高血压1例,重度子痫前期1例,未发生严重的分娩并发症。结论:在胎儿医学框架下进行的氯化钾减胎技术用于早中孕期减胎安全有效,改善了多胎妊娠的围产儿结局。     

妊娠合并干燥综合征患者母儿结局及相关因素分析

目的探讨妊娠合并原发性干燥综合征患者母儿结局及相关因素。方法选取2008年1月至2020年5月间就诊于北京大学人民医院产科的原发性干燥综合征患者52例为研究组;随机选取同期在本院建档的单胎妊娠260例作为正常对照组。研究组按照诊断时间分为孕前诊断组和孕期诊断组。结果 52例患者共56次妊娠,无孕产妇死亡,共获得活产新生儿55例(98.2%),胎死宫内1例次(1.8%)。分娩孕周(38.15±1.90),阴道分娩例27例(48.2%),剖宫产29例(51.8%)。研究组与对照组平均年龄[(31.89±3.55)vs(30.81±3.73)]岁,P=0.035;平均分娩孕周[(38.15±1.90) vs (39.36±1.23)]周,P 0.001;新生儿平均体重[(2 985.27±515.90)vs(3 372.54±431.87)]g,P 0.001;早产(16.1%vs 3.8%,P=0.002);子痫前期(5.4%vs 0.8%,P=0.041)、剖宫产率(51.8%vs 22.7%,P 0.001)均低于对照组,差异有统计学意义(P 0.05)。孕期诊断组较孕前诊断组分娩孕周低[(36.26±2.76)vs (38.34±1.73)]周,P=0.018),子痫前期的发生率高(33.3%vs 2%,P=0.028),差异有统计学意义(P 0.05)。结论妊娠合并原发性干燥综合征患者妊娠并发症高,早产、子痫前期发生率增加。     

不同绒毛膜性自然受孕双胎围产结局分析

目的:回顾分析自然受孕双胎妊娠相关资料,探讨不同绒毛膜性双胎的围产结局。方法:选取2015年6月至2018年5月于福建医科大学附属福建省妇幼保健院产检和分娩(28周以上)的自然受孕双胎妊娠孕妇,其中单绒毛膜双胎(MCT组)321例,根据年龄、孕前体质量指数(BMI)1∶1对照原则,选取同期双绒毛膜双胎(DCT组)321例,分析两组围产结局的差异。结果:642例双胎孕妇的平均年龄为(29.03±4.53)岁,孕前BMI为(20.73±2.51)kg/m~2,分娩孕周平均为(35.58±2.21)周,新生儿平均出生体重为(2148.89±221.4)g。母、儿围产结局发生前五位的分别为:早产、贫血、胎膜早破、GDM和妊娠期高血压疾病;新生儿高胆红素血症、新生儿畸形、双胎出生体重不一致、小于胎龄儿和新生儿窒息。其中早产的发生率最高,为55.61%。MCT组的早产、34周早产、脐带帆状附着、双胎出生体重不一致的发生率高于DCT组,但新生儿畸形、新生儿高胆红素血症发生率低于DCT组,差异均有统计学意义(P0.05)。两组的妊娠期高血压疾病、胎膜早破、贫血、前置胎盘、胎盘早剥、一胎羊水过多、剖宫产率,以及新生儿窒息、小于胎龄儿、围产儿死亡发生率等方面比较,差异均无统计学意义(P0.05)。结论:单绒毛膜性双胎增加母儿不良妊娠结局的发生率,根据双胎绒毛膜性做好详细的孕期保健,对提高母儿围产结局具有重要意义。     

辅助生殖技术受孕和自然受孕双胎妊娠结局的临床比较

目的:探讨辅助生殖技术(ART)受孕双胎妊娠与自然受孕双胎妊娠围生期的结局。方法:回顾分析93例ART受孕双胎妊娠孕妇(研究组)的并发症、分娩方式及围产儿结局,并与同期自然受孕双胎(对照组)451例比较。结果:研究组孕妇平均年龄较高(32.5±3.6岁),分娩孕周较小(33.4±4.3周),住院时间较长(21.1±2.6天),与对照组相比(分别为27.8±3.2岁、35.6±4.1周、11.3±1.5天)差异有显著性(P<0.05)。研究组早产、妊娠期高血压疾病、胎膜早破、前置胎盘、羊水过多的发生率明显高于对照组,两者差异有显著性(P<0.05)。研究组双胎输血综合征明显少于对照组(P<0.01)。两组剖宫产率均在72%以上,差异无统计学意义。研究组新生儿出生体重低、新生儿畸形和新生儿转NICU率高,与对照组相比有统计学差异(P<0.05)。研究组双胎之一胎死宫内率低于对照组(P<0.01)。结论:ART受孕双胎并发症和不良新生儿结局风险大,加强ART受孕双胎妊娠并发症的防治和产前、产时监护,产儿科密切合作和新生儿护理具有重要意义。     

三胎妊娠早孕期减胎术后的围生结局分析

目的:探讨三胎妊娠早孕期选择性氯化钾减胎术后与未减胎单胎或双胎妊娠的围生结局差异。方法:收集广州医科大学附属第三医院2012年1月至2017年10月诊治的181例三胎妊娠孕妇早孕期行胎儿心内注射氯化钾减胎术(减至单胎组103例,减至双胎组78例)和未减胎单胎妊娠、双胎妊娠(未减胎单胎组58例,未减胎双胎组54例)的临床信息,并对比分析围生结局差异。结果:减至单胎组分别与减至双胎组和未减胎单胎组相比,其流产率(16.50%、3.85%、1.72%)和早产率(16.50%、55.13%、3.45%)、分娩孕周(37.37±0.26周、34.60±0.29周、39.05±0.20周)及新生儿出生体质量(2.71±0.06 kg、2.12±0.54 kg、3.07±0.07 kg)比较,差异均有统计学意义(P0.05)。减至双胎组与未减胎双胎组比较,其早产率(55.13%、35.19%)、分娩孕周(34.60±0.29周、36.04±0.27周)及新生儿出生体质量(2.12±0.54 kg、2.37±0.07 kg),差异有统计学意义(P0.05)。结论:尽管减胎术增加了孕妇早产率,但通过选择性减胎控制胎儿的数量来降低孕产期并发症仍是必要的。综合考虑流产率、早产率和胎儿发病风险,保留单胎可能更有利于胎儿围生结局和远期健康结局。     

前置血管的研究进展

前置血管为罕见的妊娠期并发症,前置血管破裂会导致胎儿失血性休克甚至死亡,是构成围产儿死亡的重要原因之一。产前诊断前置血管是降低围产儿死亡率的关键,应对合并相关高危因素的孕妇实行前置血管的标准化筛查,并选择合适的分娩孕周及时终止妊娠,以改善围产结局。     

前置血管5例临床特征分析

目的:探讨前置血管的临床特点及围生儿结局。方法:回顾性分析2005年1月至2012年12月在四川大学华西第二医院分娩的、产后确诊的5例前置血管患者的临床资料。结果:5例患者中,产前经腹部B超检查诊断3例,产前B超诊断率60%,产前诊断的平均孕周为25+2周;产后明确诊断2例。5例均存在高危因素,分别为:低置胎盘2例,合并帆状胎盘2例,合并球拍状胎盘2例,合并副胎盘1例,体外受精-胚胎移植术后1例。产前诊断的3例患者临产前行择期剖宫产,围生儿结局良好;产后诊断的2例患者,1例因疑"胎儿窘迫"急行剖宫产,术后新生儿转入NICU,另一例入院前发生胎膜早破、前置血管破裂,胎死宫内引产。结论:超声检查是产前诊断前置血管的主要方法,加强对高危人群的筛查、提高产前诊断率和临产前行剖宫产可改善围生儿结局。     

辅助生殖与自然受孕双胎妊娠围产结局比较——附1524例临床分析

目的:了解辅助生育技术(ART)是否会增加双胎妊娠的产科并发症和围产儿风险。方法:回顾性分析产前检查及分娩的760例辅助生育受孕双胎孕妇(ART组)和764例自然受孕双胎孕妇(对照组)的妊娠期并发症及新生儿结局。结果:ART组孕妇平均年龄(32.7±3.5岁)高于对照组(30.0±3.7岁),差异有统计学意义(P0.05);ART组前置胎盘、产后出血及妊娠期糖尿病发生率高于对照组,差异有统计学意义(P0.05);ART组择期剖宫产率为85.52%,高于对照组(80.09%),其急诊剖宫产导致早产的比例低于对照组,差异有统计学意义(P0.05);新生儿出生体质量、新生儿窒息率、先天畸形发生率及新生儿死亡率组间无统计学差异(P0.05)。结论:ART在双胎妊娠中会增加前置胎盘、产后出血及妊娠期糖尿病的发生率,但并不增加其他产科主要并发症及围产儿风险,因此,辅助生育受孕双胎孕妇并无预防性减胎的必要。     

血管前置的产前超声诊断

目的探讨血管前置的高危因素和产前超声诊断的价值。 方法回顾性分析2012年1月至2014年6月就诊于广东省妇幼保健院行产前超声检查和(或)临床诊断为妊娠合并血管前置患者的超声声像图资料,并追踪妊娠结局。 结果产前超声共检出血管前置18例,其中1例脐带先露误诊为血管前置;漏诊1例。确诊为血管前置病例共计18例,其中16例(88.9%,16/18)为单胎妊娠,2例(11.1%,2/18)为三胎妊娠;合并低置胎盘9例(50.0%,9/18),帆状胎盘8例(44.4%,8/18),副胎盘2例(11.1%,2/18),球拍状胎盘2例(11.1%,2/18),单脐动脉3例(16.8%,3/18)。18例胎儿中,早产9例(50.0%,9/18),足月产8例(44.4%,8/18),1例(5.6%,1/18)因胎儿结构异常引产。产前超声检查漏诊的1例患者,足月妊娠经阴道分娩时大出血,胎儿死亡。 结论胎盘异常是血管前置的高危因素,需重视产前超声检查,及时诊断和处理,可有效避免不良妊娠结局的发生。     

Vasa previa: prenatal diagnosis, natural evolution, and clinical outcome

OBJECTIVE: To describe the prenatal ultrasonographic diagnosis, natural evolution, and clinical outcomes of vasa previa in a large population at a single institution. METHODS: We attempted to view the internal cervical os of 93,874 women with second- and third-trimester pregnancies during an 8-year period. Echogenic parallel or circular lines near the cervix, seen by gray-scale ultrasonography, raised the possibility of vasa previa. Diagnosis was confirmed by Doppler and endovaginal studies if aberrant vessels over the internal cervical os were suspected. Abnormal placental morphology and velamentous cord insertion were documented if they were identified during prenatal scans. Ultrasonographic findings were correlated with clinical courses, perinatal outcomes, and placental pathology examinations. RESULTS: Eighteen cases of vasa previa were suspected at a mean (+/- standard deviation) gestational age of 26.0 +/- 6.3 weeks; the earliest diagnosis was at 15.6 weeks' gestation. Eight of those cases initially showed placental edge over the internal os and later developed vasa previa after the placenta "receded" from the cervix. Six women had mild vaginal bleeding at a mean gestational age of 31.3 weeks. Three women had normal late third-trimester scans and were allowed to have uncomplicated vaginal deliveries. The remaining subjects delivered by cesarean. There were two deaths (one fetal and one neonatal), and minor preterm complications slightly prolonged infant hospitalizations. One set of preterm twins needed neonatal transfusions. Pathology findings included ten cases of velamentous insertion and three cases each of bilobed placentas, succenturiate lobes, and marginal cord insertion. CONCLUSION: Vasa previa was detected in asymptomatic women as early as the second trimester. Perinatal outcome was generally favorable, although several infants had slightly extended newborn nursery admissions due to mild complications of prematurity.     

The effect of placenta previa on neonatal mortality: a population-based study in the United States, 1989 through 1997

OBJECTIVE: The purpose of the study was to explore the associations of placenta previa with preterm delivery, growth restriction, and neonatal survival. STUDY DESIGN: A retrospective cohort study was performed of live births in the United States (1989-1991 and 1995-1997) that used the national linked birth/infant death records from 22,368,235 singleton pregnancies. The diagnosis of previa was restricted to those live births that were delivered (> or =24 weeks) by cesarean delivery. We evaluated gestational age and birth weight-specific risk of neonatal deaths (within the first 28 days) in relation to placenta previa. Fetal growth was assessed in centiles of birth weight (<3rd, 3rd-4th, 5th-9th, 10th-90th, and >90th centile), adjusted for gestational age. All analyses were adjusted for the confounding effects of the year of delivery, maternal age, gravidity, education, prenatal care, marital status, and race/ethnicity. RESULTS: Placenta previa was recorded in 2.8 per 1000 live births (n = 61,711). Neonatal mortality rate was 10.7 with previa, compared with 2.5 per 1,000 among other pregnancies (relative risk, 4.3; 95% confidence interval, 4.0,4.8). At 28 to 36 weeks, babies born to women with placenta previa weighed, on average, 210 g lower than babies born to women without placenta previa (P <.001). Compared with babies born to women without previa, the risk of death from placenta previa was lower among preterm babies (<37 weeks of gestation), with a crossover at 37 weeks where the mortality rate was higher for babies born to women with placenta previa than for babies born to women without placenta previa. This crossover also persisted in an analysis by birth weight and term births (delivered at > or =37 weeks of gestation). Mortality rates for term births were higher among babies born to women with placenta previa than among babies born women without placenta previa who were at the 10th to 90th centile (relative risk, 1.9; 95% confidence interval, 1.3, 2.8), and those at >90th centile (relative risk, 3.6; 95% confidence interval, 1.3, 9.6). Among preterm births, however, placenta previa was not associated with increased neonatal mortality by fetal growth centiles. CONCLUSION: The risk of neonatal mortality was higher for babies born to women with placenta previa than for babies born to women without placenta previa who were delivered at > or =37 weeks of gestation. Pregnancies that are diagnosed with placenta previa must be monitored carefully, especially as they approach term.     

Diagnóstico prenatal de vasa previa

ObjectivePrenatal diagnosis of vasa previa in cord insertion anomaliesMaterial and methodWe examined six cases of cord insertion anomalies or placentation anomaliesResultsThree cases were diagnosed of vessels previous the presentation and near the internal cervical orifice. Two cases of twin pregnancy with a cord velamentous insertion of the second twin on the partition membrane, the situation of the insertions showed a clinical vasa previa of the second twin after the potential birth of the first twin. The last case showed an interplacental vascular septum, in a bilobed placenta, that was previous to the presentation and near the internal cervical orificeConclusionThe bidimensional ultrasounds, the pulsed and color Doppler studies allowed the prenatal diagnosis of the vasa previa in the asymptomatic pregnancies. Its diagnosis was based in its suspect in cases with a velamentous insertion or with a bilobed placenta. In these situations, a detailed evaluation of the relation of the amniotic umbilical vessels with the inferior uterine segment or with the uterine region previous to the fetus will allow the diagnosis of the vasa previa     

Placenta previa: neonatal death after live births in the United States

OBJECTIVE: The purpose of this study was to describe neonatal mortality rates among live births that were complicated by placenta previa in the United States. STUDY DESIGN: This was a population-based retrospective cohort study of 1997 United States singleton live births. Neonatal deaths among pregnancies that were complicated by placenta previa were compared with deaths among pregnancies with no placenta previa. Adjusted and unadjusted hazard ratios were generated from a proportional hazards regression model. RESULTS: Of 3,773,369 live births, 9656 were complicated by placenta previa (2.6 cases per 1000). Among cases of placenta previa, 114 neonatal deaths occurred (11.8 per 1000) versus 14951 (4 per 1000) among non-placenta previa neonates (P <.0001). The adjusted relative risk of death was three times higher among placenta previa neonates (hazard ratio, 3.06; 95% CI, 2.40-3.94). Placenta previa-related death was mediated through preterm delivery rather than small for gestational age. CONCLUSION: Placenta previa triples the rate of neonatal mortality, which is mediated mainly through preterm birth.     

Placenta previa in singleton and twin births in the United States, 1989 through 1998: a comparison of risk factor profiles and associated conditions

OBJECTIVE: The purpose of this study was to compare risk factor profiles for placenta previa between singleton and twin live births. STUDY DESIGN: This cohort study was based on United States natality data files (1989 through 1998) and comprised 37,956,020 singleton births and 961,578 twin births. Women who were diagnosed with placenta previa were included only if they were delivered by cesarean delivery. Risk factors for placenta previa that were examined included sociodemographic (age, gravidity, education, marital status, and race), behavioral (prenatal care, smoking, and alcohol use), previous preterm birth, and medical and obstetric factors. Effect modification between maternal age and gravidity and the dose-response relationship with number of cigarettes smoked/day on placenta previa risk were also evaluated. RESULTS: The rate of placenta previa was 40% higher among twin births (3.9 per 1,000 live births, n = 3,793 births) than among singleton births (2.8 per 1,000 live births, n = 104,754 births). Comparison of risk factors for placenta previa between the singleton and twin births revealed fairly similar risk factor profiles. Compared with primigravid women <20 years old, the risk for placenta previa increased by advancing age and by increasing number of pregnancies among both singleton and twin births. The number of cigarettes smoked per day also showed a dose-response trend for placenta previa risk in the two groups. CONCLUSION: The increased rate of placenta previa among twin births underscores the need to monitor carefully such pregnancies with heightened suspicion and awareness for the development of this condition.     

Obstetric and Neonatal Outcomes in People Who Acquired a Spinal Cord Injury During Pregnancy

ObjectiveThe objectives of this study were to determine the obstetric and neonatal outcomes of people who acquired spinal cord injuries (SCI) during pregnancy.MethodsThis is part of an international observational questionnaire examining pregnancy outcomes of people with SCI. The outcome measures included demographics, level of injury and American Spinal Injury Association scores, prenatal and postnatal complications, and neonatal outcomes.ResultsOf 780 responses, 14 (1.79%) participants reported acquiring an SCI while pregnant. 64.2% (9/14) of injuries were due to trauma. Of 14 pregnancies, 1 person miscarried, and 3 pregnancies were terminated. There were 11 live births. One participant had twins and 9 live births were singletons. Six participants delivered vaginally, 3 had a cesarean delivery and 1 was unreported. The preterm birth rate was 54.5% (6/11). Approximately 36% (4/11) of newborns were admitted to the neonatal intensive care unit. The average birth weight reported was 2409.7 g (456.3 g–3458.6 g). Forty percent (4/10) of participants reported experiencing postpartum blues or depression. Sixty percent (6/10) of participants breastfed for over 2 weeks.ConclusionsThis is the largest known cohort to date of persons acquiring SCI during pregnancy. The most common cause of SCI was a motor vehicle accident. Complications included preterm birth and neonatal intensive care unit admission. People who have an SCI during pregnancy are at risk for complications; however, positive pregnancy and neonatal outcomes are possible. Absolute small numbers of this event limit the ability to assess incidence of outcomes.     

Previous cesarean delivery and risks of placenta previa and placental abruption

OBJECTIVE: To examine the association between cesarean delivery and previa and abruption in subsequent pregnancies. METHODS: A retrospective cohort study of first 2 (n = 156,475) and first 3 (n = 31,102) consecutive singleton pregnancies using the 1989-1997 Missouri longitudinally linked data were performed. Relative risk (RR) was used to quantify the associations between cesarean delivery and risks of previa and abruption in subsequent pregnancies, after adjusting for several confounders. RESULTS: Rates of previa and abruption were 4.4 (n = 694) and 7.9 (n = 1,243) per 1,000 births, respectively. The pregnancy after a cesarean delivery was associated with increased risk of previa (0.63%) compared with a vaginal delivery (0.38%, RR 1.5, 95% confidence interval [CI] 1.3-1.8). Cesarean delivery in the first and second births conferred a two-fold increased risk of previa in the third pregnancy (RR 2.0, 95% CI 1.3-3.0) compared with first two vaginal deliveries. Women with a cesarean first birth were more likely to have an abruption in the second pregnancy (0.95%) compared with women who had a vaginal first birth (0.74%, RR 1.3, 95% CI 1.2-1.5). Two consecutive cesarean deliveries were associated with a 30% increased risk of abruption in the third pregnancy (RR 1.3, 95% CI 1.0-1.8). A second pregnancy within a year after a cesarean delivery was associated with increased risks of previa (RR 1.7, 95% CI 0.9-3.1) and abruption (RR 1.5, 95% CI 1.1-2.3). CONCLUSION: A cesarean first birth is associated with increased risks of previa and abruption in the second pregnancy. There is a dose-response pattern in the risk of previa, with increasing number of prior cesarean deliveries. A short interpregnancy interval is associated with increased risks of previa and abruption. LEVEL OF EVIDENCE: II-2.     

Guidelines for the Management of Vasa Previa

ObjectivesTo describe the etiology of vasa previa and the risk factors and associated condition, to identify the various clinical presentations of vasa previa, to describe the ultrasound tools used in its diagnosis, and to describe the management of vasa previa.OutcomesReduction of perinatal mortality, short-term neonatal morbidity, long-term infant morbidity, and short-term and long-term maternal morbidity and mortality.EvidencePublished literature on randomized trials, prospective cohort studies, and selected retrospective cohort studies was retrieved through searches of PubMed or Medline, CINAHL, and the Cochrane Library, using appropriate controlled vocabulary (e.g., selected epidemiological studies comparing delivery by Caesarean section with vaginal delivery; studies comparing outcomes when vasa previa is diagnosed antenatally vs. intrapartum) and key words (e.g., vasa previa). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. Searches were updated on a regular basis and incorporated into the guideline to October 1, 2008. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and from national and international medical specialty societies.ValuesThe evidence collected was reviewed by the Diagnostic Imaging Committee and the Maternal Fetal Medicine Committee of the Society of Obstetricians and Gynaecologists of Canada (SOGC) and quantified using the evaluation of evidence guidelines developed by the Canadian Task Force on Preventive Health Care.Benefits, Harms, and CostsThe benefit expected from this guideline is facilitation of optimal and uniform care for pregnancies complicated by vasa previa.SponsorsThe Society of Obstetricians and Gynaecologists of Canada.Summary StatementA comparison of women who were diagnosed antenatally and those who were not shows respective neonatal survival rates of 97% and 44%, and neonatal blood transfusion rates of 3.4% and 58.5%, respectively. Vasa previa can be diagnosed antenatally, using combined abdominal and transvaginal ultrasound and colour flow mapping; however, many cases are not diagnosed, and not making such a diagnosis is still acceptable. Even under the best circumstances the false positive rate is extremely low. (II-2)Recommendations

• 1.If the placenta is found to be low lying at the routine second trimester ultrasound examination, further evaluation for placental cord insertion should be performed. (II-2B)
• 2.Transvaginal ultrasound may be considered for all women at high risk for vasa previa, including those with low or velamentous insertion of the cord, bilobate or succenturiate placenta, or for those having vaginal bleeding, in order to evaluate the internal cervical os. (II-2B)
• 3.If vasa previa is suspected, transvaginal ultrasound colour Doppler may be used to facilitate the diagnosis. Even with the use of transvaginal ultrasound colour Doppler, vasa previa may be missed. (II-2B)
• 4.When vasa previa is diagnosed antenatally, an elective Caesarean section should be offered prior to the onset of labour. (II-1A)
• 5.In cases of vasa previa, premature delivery is most likely; therefore, consideration should be given to administration of corticosteroids at 28 to 32 weeks to promote fetal lung maturation and to hospitalization at about 30 to 32 weeks. (II-2B)
• 6.In a woman with an antenatal diagnosis of vasa previa, when there has been bleeding or premature rupture of membranes, the woman should be offered delivery in a birthing unit with continuous electronic fetal heart rate monitoring and, if time permits, a rapid biochemical test for fetal hemoglobin, to be done as soon as possible; if any of the above tests are abnormal, an urgent Caesarean section should be performed. (III-B)
• 7.Women admitted with diagnosed vasa previa should ideally be transferred for delivery in a tertiary facility where a pediatrician and blood for neonatal transfusion are immediately available in case aggressive resuscitation of the neonate is necessary. (II-3B)
• 8.Women admitted to a tertiary care unit with a diagnosis of vasa previa should have this diagnosis clearly identified on the chart, and all health care providers should be made aware of the potential need for immediate delivery by Caesarean section if vaginal bleeding occurs. (III-B)

     

Placenta previa and the risk of preterm delivery.

OBJECTIVES: We aimed to quantify the risk of preterm delivery and maternal and neonatal morbidities associated with placenta previa. STUDY DESIGN: We conducted a retrospective cohort study of singleton births that occurred between 1976 and 2001, examining outcomes including preterm delivery and perinatal complications. Multivariate logistic regression was used to control for potential confounders. Kaplan-Meier survival curves were constructed to compare preterm delivery in pregnancies complicated by previa vs. no previa. RESULTS: Among the 38 540 women, 230 women had previas (0.6%). Compared to controls, pregnancies with previa were significantly associated with preterm delivery prior to 28 weeks (3.5% vs. 1.3%; p = 0.003), 32 weeks (11.7% vs. 2.5%; p < 0.001), and 34 weeks (16.1% vs. 3.0%; p < 0.001) of gestation. Patients with previa were more likely to be diagnosed with postpartum hemorrhage (59.7% vs. 17.3%; p < 0.001) and to receive a blood transfusion (11.8% vs. 1.1%; p < 0.001). Survival curves demonstrate the risk of preterm delivery at each week and showed an overall higher rate of preterm delivery for patients with a placenta previa. CONCLUSIONS: Placenta previa is associated with maternal and neonatal complications, including preterm delivery and postpartum hemorrhage. These specific outcomes can be used to counsel women with previa.