Why STAN might not be dead

Recently, a meta-analysis, including 26?526 laboring vertex singletons at term, summarized all available level-1 data from six high-quality randomized clinical trials (RCTs) on the use of ST analysis (STAN) during labor as an adjunct to conventional intrapartum fetal heart rate monitoring. The meta-analysis showed that STAN did not improve perinatal outcomes or decrease cesarean deliveries. Nonetheless, there are still reasons to believe STAN may have a role in the future research on intrapartum fetal monitoring. Out of six trials included in the meta-analysis, two included all cephalic singletons in labor, and four enrolled only high-risk pregnant women. This combination of both low- and high-risk populations may have distorted the potential impact of STAN. The test for heterogeneity between both subgroups was found to be statistically significant, indicating that the effect of STAN was different in high-risk women compared to a combination of both low- and high-risk women. Furthermore, the classifications of the fetal heart rate patterns used in the included randomized trials were different. Last but not least, despite?>26?000 women with singleton gestations were included in the meta-analysis, the evidence still suffers from a lack of power, especially for subgroup analyses. In summary, while the level-1 data so far indicate overall no perinatal benefit of adding STAN to conventional intrapartum fetal heart rate monitoring for the outcomes most of interest, several issues point to the fact that more research is needed before the STAN technology can be deemed of no value for fetal monitoring in labor.     

Appraisal of trimester-specific fetal heart rate and its role in gestational age prediction

IntroductionThe aim of this study was to evaluate and report normal sonographic FHR values among low-risk singleton women across the three trimesters of pregnancy and determine FHR role in gestational age prediction.MethodA prospective cross-sectional study of 2727 low-risk singleton pregnant women was undertaken. FHR measurements were obtained by a consultant radiologist and three experienced sonographers using transabdominal approach from January 2019 to December 2020. Two FHR measurements were taken for each participant. The fetal lie and presentation were also documented in the first trimester. Data were analysed using SPSS version 24 (IBM, Armonk, NY, USA).ResultThe maternal mean ± SD age was 25.8 ± 6.5 years and mean FHR for first, second and third trimesters were 151 ± 16, 145 ± 6 and 125±6 bpm respectively. The mean ± SD gestational age were 10 ± 2, 19 ± 3 and 34 ± 2 weeks for the first, second and third trimester respectively. Using ANOVA, there were statistically significant differences in FHR across the three trimesters (p ≤ 0.05). A positive correlation existed between maternal age and FHR (r = 0.57, p ≤ 0.05).ConclusionThis study has established normal values for FHR in first, second and third trimester respectively. Referring physicians, radiologists, sonographers, obstetricians and gynaecologists may consider FHR of (135–167) bpm (139–151) bpm and (119–131) bpm as normal FHR ranges for the first, second and third trimester respectively. This study has also revealed the possibility of gestational age prediction using FHR with the equation [Gestational Age = 87.8 – (0.47) FHR].Implications for practiceThis paper provides the most up-to-date sonographic FHR recommendations for fetal management. More importantly, findings from this study also suggests that ultrasound practitioners can use FHR measurements as a reliable alternative for fetal dating.     

An algorithm for the recovery of fetal heart rate series from CTG data

Cardiotocography (simultaneous recording of fetal heart rate (FHR) and uterine contractions) is one of the most used diagnostic techniques to evaluate fetal well-being and to investigate the functional state of the fetal autonomic nervous system. Recently, great interest has been paid to the variability of the FHR, and its frequency analysis, as a base for a more objective analysis of the cardiotocographic (CTG) tracings. FHR signals are unevenly sampled series. To obtain evenly sampled series, cardiotocographs often use zero-order interpolation. Such process is simple and fast but results unsuitable for frequency analyses because it introduces alterations in the FHR power spectrum. An algorithm for the recovery of the true FHR series out of the zero-order interpolated CTG data was developed and evaluated.     

The future of electronic fetal monitoring

Continuous electronic fetal monitoring (EFM) was first introduced commercially over 50 years ago with the hope of improving perinatal outcomes during labor. However, despite the increased use of EFM, definitive improvements in perinatal outcomes have not been demonstrated. Variance in tracing interpretation and intervention has led to increased rates of cesarean and operative vaginal deliveries and perhaps increased maternal and neonatal morbidity. Since its inception, several strategies have been developed in hopes of optimizing EFM and improving these outcomes. We discuss the current standards of intrapartum fetal monitoring and review optimization strategies and technologies in development to improve intrapartum fetal monitoring.     

A comparison of performance by medical and midwifery students in multiprofessional teaching

AIM: At Dundee University, midwifery and medical students are taught obstetrics together in a 2-week intensive course. We set out to test the hypothesis that staff time and effort could be saved by using shared resources in teaching a multidisciplinary group of students to an acceptable level. METHOD: In order to measure the knowledge gain by two different groups of students, we tested the students before and after a timetabled computer-assisted learning (CAL) session focusing on how to interpret a cardiotocograph (CTG). Also, half of each student group was given extra CTG teaching before the CAL session. RESULTS: The medical students (n=38) increased their median score from 9 to 17 after the CAL (P<0.001) but the midwifery students (n=13) only increased their median score from 12 to 14 after the CAL (n.s.). However, when given a tutorial and CAL, the post-test scores for both medical and midwifery students were similar and significantly higher than pre-test scores (median score increase from 8.5 to 18 for medical students, P<0.001, n=34, and from 9 to 16 for midwifery students, P<0.01 n=11). There was no significant knowledge gain by the medical students who undertook the additional tutorial. CONCLUSION: We conclude that shared resources could be used by medical and midwifery students to reach equivalent levels of skill in CTG interpretation. However, in order to achieve equivalence, staff time and effort was wasted as medical students were given unnecessary tuition.     

氧化亚氮吸入分娩镇痛对产程中胎心率的影响

目的:探讨氧化亚氮吸入分娩镇痛对产程中胎心率的影响。方法:随机选择2003年8月~2004年6月分娩的足月、单胎、头位、无阴道分娩禁忌症且宫口扩张≥3cm的一对一专责助产士陪伴分娩的初产妇876例,以自愿接受氧化亚氮吸入分娩镇痛的438例作为研究组,未采用任何药物进行分娩镇痛的438例作为对照组,镇痛前、后监护胎心率直至胎儿娩出。结果:尽管两组间胎儿窘迫及新生儿窒息率无显著性差异,但研究组在产程活跃期胎心率加速减少,基线细变异减少,出现频发早期减速以及迟发减速者多于对照组。结论:使用氧化亚氮吸入分娩镇痛有必要密切监护胎心率的变化以及早发现胎儿缺氧,及时处理,避免胎儿窘迫和新生儿窒息。     

脐带绕颈产时胎心监护异常的临床分析

目的：探讨脐带绕颈产时胎心监护异常的临床处理。方法：回顾分析2003年7月～2005年3月收治的193例脐带绕颈（观察组）和163例无脐带绕颈（对照组）的临床资料。结果：观察组胎儿窘迫率，阴道助产率显著高于对照组（P〈0．05）。两组新生儿窒息率、剖宫产率差异无显著性（P〉0．05）。结论：脐带绕颈产时胎心监护异常，通过适当处理、可降低新生儿窒息率和剖宫产率。     

脐血乳酸水平、产时胎心监护不良图形和新生儿结局关系的研究

目的:研究脐动脉血乳酸水平与产时胎心监护不良图形及新生儿结局之间的关系。方法:229例足月妊娠、单胎、头位产妇根据产时胎心宫缩图(cardiotocography,CTG)分为两组,观察组:轻度变异减速(variable deceleration,VD)68例、不良CTG包括中、重度VD、不典型VD、胎心基线变异减弱或消失、延长减速、重度晚期减速及心动过缓84例。对照组:产时CTG无VD及不良图形、新生儿脐动脉血pH≥7.20的产妇77例,检测新生儿脐动脉血乳酸浓度及生后20项行为神经评分(neonatal behavioral neudogioal as-sessment,NBNA)。结果:对照组脐动脉血乳酸99%参考值范围为1.31~4.05mmol/L,不良CTG脐血乳酸水平明显高于对照组(P<0.01);pH、BE值显著低于对照组与轻度VD组(P<0.01,P<0.05),脐血乳酸水平与pH、BE呈显著负相关(P<0.01)。以对照组x-±2.58s为界值,观察组脐血乳酸超过界值者不良CTG占73.33%,其中不良结局儿占68.18%。结论:脐动脉乳酸水平与pH、BE值有较好的相关性。产时重度VD或VD并存其它异常CTG,胎心基线变异减弱,尤其伴发羊水粪染、脐带异常时与围生儿脐血高乳酸水平、不良结局有关。     

Short-term neonatal outcome in diabetic versus non-diabetic pregnancies complicated by non-reassuring foetal heart rate tracings

Abstract

Objective: Analysis of the impact of non-reassuring foetal heart rate patterns (FHR) and suspected foetal distress during active labour on the neonatal outcome in diabetic compared to non-diabetic mothers.

Methods: Retrospective case–control study comparing the short-term neonatal outcome including Apgar score at 5?min, and arterial/venous umbilical cord blood pH of 57 deliveries of women with different types of diabetes and 114 healthy controls. Patients were selected out of all deliveries with suspected foetal distress during active labour and performed foetal scalp pH samplings (n?=?590) at the Medical University of Graz, Austria, during 2008–2009.

Results: Arterial pH was significantly lower in the diabetic group (7.215 versus 7.250, p?=?0.007). Apgar scores (?>?8) at 5?min were similar in both groups (96.5% versus 95.6%, p?=?0.566). The percentage of cases with foetal scalp blood pH <7.25 was higher in the diabetes group, but did not reach statistical significance (14.1% versus 7.1%, p?=?0.166).

Conclusions: Newborns of women with gestational and type 1 diabetes and non-reassuring FHR tracing have significantly lower arterial cord blood pH values without consequences on neonatal postpartum adaptation. Special attention to pathological changes in FHR patterns and to the more rapid decline in foetal pH during periods of foetal distress may be warranted in women with gestational and pre-conceptional diabetes during active labour. More frequent foetal scalp pH testing to rule out clinically relevant foetal acidosis needs to be discussed.     

脐血流和胎心监护对妊娠期肝内胆汁淤积症患者胎儿监护的临床价值

目的:探讨B超测定脐动脉血流和胎心监护对妊娠期肝内胆汁淤积症(ICP)患者胎儿监护的临床意义。方法:将675例ICP孕妇分为4组。S/D>3者356例,其中胎心监护异常196例为A组,胎心监护正常160例为B组。S/D<3者319例,其中胎心监护异常145例为C组,胎心监护正常174例为D组。分析4组羊水污染、新生儿窒息、围产儿死亡情况。结果:A组羊水污染,新生儿窒息等最高,其次是C、B组,最低D组。结论:ICP孕妇产前脐血流S/D<3者,应密切监测胎心,延长孕周,严密观察下阴道分娩。S/D>3者,胎心监护异常,尽快终止妊娠。