背景:大于胎龄胎儿的妊娠发生不良母婴结局的风险增加。在这种怀孕中如何管理分娩存在不确定性。目前的指导方针建议与女性讨论各种选择的利弊,包括期待管理,引产和剖腹产。为了让女性能够做出关于出生的明智决定,产前检测胎龄大是必不可少的。
目的:探讨产前超声扫描预测出生时胎龄大的能力。
方法:在这项回顾性队列研究中,我们分析了来自西米德兰兹郡的常规数据库的数据,联合王国。我们纳入了在妊娠35+0和38+0周之间进行了产前超声检查的孕妇,以及一个亚组,扫描的原因是胎儿被怀疑是大的。胎龄大被定义为>90个定制的增长百分位数,估计胎儿体重以及新生儿体重。我们还测试了非定制标准的性能,Hadlock胎儿体重>90分位数,新生儿体重>4kg。我们计算了整个人群以及具有不同母体体重指数的组的诊断特征。
结果:研究队列包括26,527例孕妇,平均在妊娠256天进行扫描,20天后分娩,中位时间为276天(四分位距15)。总共2241(8.4%)的新生儿按定制百分位数计算胎龄较大,其中1459人(65.1%)的扫描估计胎儿体重>90百分位,假阳性率为8.6%,阳性预测值为41.0%。在912例(3.4%)怀孕的亚组中,对可疑的大胎儿进行了扫描,293(32.1%)婴儿出生时胎龄较大,给出50.3%的阳性预测值,敏感性为77.1%,假阳性率为36.0%。当比较从低(<18.5kg/m2)到高体重指数(>30kg/m2)的亚组时,灵敏度从55.6%增加到67.8%,假阳性率从5.2%到11.5%,阳性预测值从32.1%到42.3%。共有2585名(9.7%)婴儿为大体(出生体重>4kg),根据Hadlock的生长标准,这1058例(40.9%)产前胎龄大(>90分),假阳性率为4.9%,阳性预测值为41.0%。在低体重指数(<18.5;诊断比值比23.0vs6.4)和高体重指数(>30;诊断比值比16.2vs8.8)方面,亚组内的分析显示,与未定制的标准相比,定制的性能更好。
结论:妊娠晚期超声评估胎儿体重的任何适应症都具有很好的识别和预测出生时胎龄大的能力。并使用定制标准进行改进。对疑似大胎儿进行超声检查时,检出率较好,然而,在更高的假阳性诊断的风险。我们的结果为妇女和临床医生提供了信息,以帮助有关怀疑胎龄较大的胎儿出生的产前决策。
BACKGROUND: Pregnancies with large-for-gestational-age fetuses are at increased risk of adverse maternal and neonatal outcomes. There is uncertainty about how to manage birth in such pregnancies. Current guidelines recommend a discussion with women of the pros and cons of options, including expectant management, induction of labor, and cesarean delivery. For women to make an informed decision about birth, antenatal detection of large for gestational age is essential.
OBJECTIVE: To investigate the ability of antenatal ultrasound scans to predict large for gestational age at birth.
METHODS: In this retrospective cohort study, we analyzed data from a routinely collected database from the West Midlands, United Kingdom. We included pregnancies that had an antenatal ultrasound-estimated fetal weight between 35+0 and 38+0 weeks gestation for any indication and a subgroup where the reason for the scan was that the fetus was suspected to be big. Large for gestational age was defined as >90th
customized GROW percentile for estimated fetal weight as well as neonatal weight. In addition, we tested the performance of an uncustomized standard, with Hadlock fetal weight >90th percentile and neonatal weight >4 kg. We calculated diagnostic characteristics for the whole population and groups with different maternal body mass indexes.
RESULTS: The study cohort consisted of 26,527 pregnancies, which, on average, had a scan at 36+4 weeks gestation and delivered 20 days later at a median of 39+3 weeks (interquartile range 15). In total, 2241 (8.4%) of neonates were large for gestational age by
customized percentiles, of which 1459 (65.1%) had a scan estimated fetal weight >90th percentile, with a false positive rate of 8.6% and a positive predictive value of 41.0%. In the subgroup of 912 (3.4%) pregnancies scanned for a suspected large fetus, 293 (32.1%) babies were large for gestational age at birth, giving a positive predictive value of 50.3%, with a sensitivity of 77.1% and false positive rate of 36.0%. When comparing subgroups from low (<18.5 kg/m2) to high body mass index (>30 kg/m2), sensitivity increased from 55.6% to 67.8%, false positive rate from 5.2% to 11.5%, and positive predictive value from 32.1% to 42.3%. A total of 2585 (9.7%) babies were macrosomic (birthweight >4 kg), and of these, 1058 (40.9%) were large for gestational age (>90th percentile) antenatally by Hadlock\'s growth standard, with a false positive rate of 4.9% and a positive predictive value 41.0%. Analysis within subgroups showed better performance by
customized than uncustomized standards for low body mass index (<18.5; diagnostic odds ratio, 23.0 vs 6.4) and high body mass index (>30; diagnostic odds ratio, 16.2 vs 8.8).
CONCLUSIONS: Late third-trimester ultrasound estimation of fetal weight for any indication has a good ability to identify and predict large for gestational age at birth and improves with the use of a
customized standard. The detection rate is better when an ultrasound is performed for a suspected large fetus but at the risk of a higher false positive diagnosis. Our results provide information for women and clinicians to aid antenatal decision-making about the birth of a fetus suspected of being large for gestational age.