Cohain Judy Slome
Midwifery Today Int Midwife. 2010 Spring(93):46-8, 67-8.
Research based on 182,492 births, wielding statistical power to uncover even mild negative associations, showed that both single and multiple nuchal cords at the time of delivery are not associated with adverse perinatal outcomes. Nuchal cords are associated with higher birth weights and lower cesarean section rates than births without nuchal cords. Color Doppler ultrasound, intended specifically to diagnose nuchal cords hours before delivery, has diagnosed the presence of 35-80% of the nuchal cords found on delivery, and has a false positive rate of 19%. The rate of nuchal cords increases with increasing gestational weeks. Present technology cannot reliably predict the presence of a nuchal cord, tell whether a nuchal cord is tight, or determine anything regarding the likelihood of hypoxia, IUGR or stillbirth. Intervention for the supposed presence of single or multiple loops of nuchal cord or a true knot, suspected by ultrasound prenatally, is unjustified because diagnosis by ultrasound is unreliable and intervention involves greater risk to the baby than the nuchal cord. Since nuchal cords occur at rates of 30-34% at 40 weeks and are not associated with adverse perinatal outcomes, practitioners and women should consider their presence reassuring and normal. Given the common occurrence of nuchal cords and its very high association with a favorable outcome, scanning for nuchal cords appears to have no efficacy. Efforts to define and diagnose new antepartum "problems" continue to outstrip our ability to improve outcomes by diagnosing and "treating" newly defined problems.
一项基于182492例分娩的研究,具备发现甚至轻微负面关联的统计效力,结果显示分娩时单根和多根脐带绕颈均与不良围产期结局无关。与无脐带绕颈的分娩相比,脐带绕颈与更高的出生体重及更低的剖宫产率相关。专门用于在分娩前数小时诊断脐带绕颈的彩色多普勒超声,能诊断出分娩时发现的35%至80%的脐带绕颈情况,且假阳性率为19%。脐带绕颈的发生率随孕周增加而上升。目前的技术无法可靠地预测脐带绕颈的存在、判断脐带绕颈是否过紧,或确定与缺氧、胎儿宫内生长受限或死产可能性相关的任何情况。对产前超声怀疑存在单根或多根脐带绕颈环或真结进行干预是不合理的,因为超声诊断不可靠,且干预对胎儿造成的风险大于脐带绕颈本身。由于40周时脐带绕颈的发生率为30%至34%,且与不良围产期结局无关,从业者和孕妇应将其视为正常且令人安心的情况。鉴于脐带绕颈很常见且与良好结局高度相关,对脐带绕颈进行扫描似乎并无效果。定义和诊断新的产前“问题”的努力,持续超过我们通过诊断和“治疗”新定义问题来改善结局的能力。