背景:在低风险妊娠中,如果观察到足高测量和胎龄差异,则需要进行妊娠晚期超声检查。尽管在超声异常检测方面有潜在的改善,迄今为止,在低风险妊娠中进行普遍的妊娠晚期超声检查的先前试验,与指示的超声检查相比,未显示新生儿或产妇不良结局的改善。
目的:主要目的是确定在低风险妊娠中进行普遍的妊娠晚期超声检查是否可以减轻新生儿的复合不良结局。次要目标是比较复合母体不良结局的变化以及胎儿生长异常(胎儿生长受限或胎龄大)或羊水异常(羊水过少或羊水过多)的检测。
方法:我们在9个地点进行的干预前后研究包括低风险妊娠;那些在妊娠晚期没有超声检查指征的妊娠。与实施前的指示超声相比,在实施后期间,所有患者均安排在36.0~37.6周进行超声检查.在这两个时期,临床医生都根据识别出的异常进行干预。复合新生儿不良结局包括以下任何一项:5分钟时Apgar评分≤5,脐带pH<7.00,产伤(骨折或臂丛神经麻痹),插管>24小时,缺氧缺血性脑病,癫痫发作,脓毒症(血培养证实的菌血症),胎粪吸入综合征,脑室出血III或IV级,脑室周围白质软化,坏死性小肠结肠炎,36周后死产,或新生儿在出生后28天内死亡。复合母体不良结局包括:绒毛膜羊膜炎,伤口感染,估计失血量>1000mL,输血,深静脉血栓或肺栓塞,入住重症监护室,或死亡。使用贝叶斯统计,我们计算了每组600人的样本量,以检测主要结局减少的概率>75%,(80%的功率;50%的假设风险降低)。
结果:在干预前阶段,在最初的超声检查中发现了747名个体,其中568名(76.0%)在36.0至37.6周符合纳入标准;在干预后期间,相应的数字分别为770和661(85.8%)。从干预前后,胎儿生长或羊水异常的发生率增加(7.1%对22.2%,p<0.0001;诊断所需的数字,7;95%置信区间,5-9).主要结局发生在前568人中的15人(2.6%)和干预后组中的661人中的12人(1.8%)(降低风险的可能性为83%,后相对风险,0.69;95%可信区间,0.34-1.42)。复合产妇不良结局发生在干预前的8.6%和干预后的6.5%(90%的风险概率(后相对风险,0.74;95%可信区间,0.49-1.15)。需要治疗以减少复合新生儿不良结局的人数为121(95%置信区间,40-200),减少复合产妇不良结局为46(95%置信区间,19-74),和防止剖宫产为18(95%置信区间,9-31).
结论:在低风险妊娠中,与指示超声检查的常规护理相比,在36.0-37.6周实施普遍的妊娠晚期超声检查,减轻了新生儿和产妇的复合不良结局。
BACKGROUND: In low-risk pregnancies, a third-trimester ultrasound examination is indicated if fundal height measurement and gestational age discrepancy are observed. Despite potential improvement in the detection of ultrasound abnormality, prior trials to date on universal third-trimester ultrasound examination in low-risk pregnancies, compared with indicated ultrasound examination, have not demonstrated improvement in neonatal or maternal adverse outcomes.
OBJECTIVE: The primary objective was to determine if universal third-trimester ultrasound examination in low-risk pregnancies could attenuate composite neonatal adverse outcomes. The secondary objectives were to compare changes in composite maternal adverse outcomes and detection of abnormalities of fetal growth (fetal growth restriction or large for gestational age) or amniotic fluid (
oligohydramnios or polyhydramnios).
METHODS: Our pre-post intervention study at 9 locations included low-risk pregnancies, those without indication for ultrasound examination in the third trimester. Compared with indicated ultrasound in the preimplementation period, in the postimplementation period, all patients were scheduled for ultrasound examination at 36.0-37.6 weeks. In both periods, clinicians intervened on the basis of abnormalities identified. Composite neonatal adverse outcomes included any of: Apgar score ≤5 at 5 minutes, cord pH <7.00, birth trauma (bone fracture or brachial plexus palsy), intubation for >24 hours, hypoxic-ischemic encephalopathy, seizure, sepsis (bacteremia proven with blood culture), meconium aspiration syndrome, intraventricular hemorrhage grade III or IV, periventricular leukomalacia, necrotizing enterocolitis, stillbirth after 36 weeks, or neonatal death within 28 days of birth. Composite maternal adverse outcomes included any of the following: chorioamnionitis, wound infection, estimated blood loss >1000 mL, blood transfusion, deep venous thrombus or pulmonary embolism, admission to intensive care unit, or death. Using Bayesian statistics, we calculated a sample size of 600 individuals in each arm to detect >75% probability of any reduction in primary outcome (80% power; 50% hypothesized risk reduction).
RESULTS: During the preintervention phase, 747 individuals were identified during the initial ultrasound examination, and among them, 568 (76.0%) met the inclusion criteria at 36.0-37.6 weeks; during the postintervention period, the corresponding numbers were 770 and 661 (85.8%). The rate of identified abnormalities of fetal growth or amniotic fluid increased from between the pre-post intervention period (7.1% vs 22.2%; P<.0001; number needed to diagnose, 7; 95% confidence interval, 5-9). The primary outcome occurred in 15 of 568 (2.6%) individuals in the preintervention and 12 of 661 (1.8%) in the postintervention group (83% probability of risk reduction; posterior relative risk, 0.69 [95% credible interval, 0.34-1.42]). The composite maternal adverse outcomes occurred in 8.6% in the preintervention and 6.5% in the postintervention group (90% probability of risk; posterior relative risk, 0.74 [95% credible interval, 0.49-1.15]). The number needed to treat to reduce composite neonatal adverse outcomes was 121 (95% confidence interval, 40-200). In addition, the number to reduce composite maternal adverse outcomes was 46 (95% confidence interval, 19-74), whereas the number to prevent cesarean delivery was 18 (95% confidence interval, 9-31).
CONCLUSIONS: Among low-risk pregnancies, compared with routine care with indicated ultrasound examination, implementation of a universal third-trimester ultrasound examination at 36.0-37.6 weeks attenuated composite neonatal and maternal adverse outcomes.