Cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram for intrapartum fetal monitoring: a Swedish randomised controlled trial. Cardiotocography only versus cardiotocography plus PR-interval analysis in intrapartum surveillance: a randomised, multicentre trial. FECG Study Group. A comparison of intrapartum automated fetal electrocardiography and conventional cardiotocography--a randomised controlled study. Plymouth randomized trial of cardiotocogram only versus ST waveform plus cardiotocogram for intrapartum monitoring in 2400 cases. Cardiotocography plus ST analysis of fetal electrocardiogram compared with cardiotocography only for intrapartum monitoring: a randomized controlled trial.
Previous studies indicate that analysis of the ST waveform of the fetal electrocardiogram provides information on the fetal response to hypoxia. We did a multicentre randomised controlled trial to test the hypothesis that intrapartum monitoring with cardiotocography combined with automatic ST-waveform analysis results in an improved perinatal outcome compared with cardiotocography alone.
                At three Swedish labour wards, 4966 women with term fetuses in the cephalic presentation entered the trial during labour after a clinical decision had been made to apply a fetal scalp electrode for internal cardiotocography. They were randomly assigned monitoring with cardiotocography plus ST analysis (CTG+ST group) or cardiotocography only (CTG group). The main outcome measure was rate of umbilical-artery metabolic acidosis (pH <7.05 and base deficit >12 mmol/L). Secondary outcomes included operative delivery for fetal distress. Results were first analysed according to intention to treat, and secondly after exclusion of cases with severe malformations or with inadequate monitoring.
                The CTG+ST group showed significantly lower rates of umbilical-artery metabolic acidosis than the cardiotocography group (15 of 2159 [0.7%] vs 31 of 2079 [2%], relative risk 0.47 [95% CI 0.25-0.86], p=0.02) and of operative delivery for fetal distress (193 of 2519 [8%] vs 227 of 2447 [9%], 0.83 [0.69-0.99], p=0.047) when all cases were included according to intention to treat. The differences were more pronounced after exclusion of 291 in the CTG+ST group and 283 in the CTG group with malformations or inadequate recording.
                Intrapartum monitoring with cardiotocography combined with automatic ST-waveform analysis increases the ability of obstetricians to identify fetal hypoxia and to intervene more appropriately, resulting in an improved perinatal outcome. There is a need to improve the sensitivity and specificity of fetal monitoring during labour. We compared the gold standard, cardiotocography, with cardiotocography plus time-interval analysis of the fetal electrocardiogram in fetal surveillance. The aim was to find out whether time-interval analysis decreased the need for operative intervention due to fetal distress.
                We did a randomised, prospective trial in five hospitals in the UK, Hong Kong, the Netherlands, and Singapore. 1038 women undergoing high-risk labours were randomly assigned fetal monitoring by cardiotocography alone, or cardiotocography plus fetal electrocardiography (ECG). Outcomes measured were rates of operative intervention, and neonatal outcome. Analysis was by intention to treat.
                515 women were assigned management by cardiotocography, and 523 cardiotocography plus fetal ECG. There was a trend towards fewer operative interventions for presumed fetal distress in the time-interval analysis plus cardiotocography group (63 [13%] vs 78 [16%]), but this was not significant (relative risk 0.80 [95% CI 0.59-1.08], p=0.17). There was no significant difference between groups in the proportion of babies who had an umbilical arterial pH of 7.15 or less (51 [11%] vs 49 [11%]; 1.01 [0.7-1.47]), or in the frequency of unsuspected acidaemia (42 [9%] vs 35 [8%]; 1.17 [0.76-1.79]).
                The addition of time-interval analysis of the fetal electrocardiogram during labour did not show a significant benefit in decreasing operative intervention. There was no significant difference in neonatal outcome. To examine whether intrapartum monitoring by means of automatic ST analysis (STAN) of fetal electrocardiography could reduce the rate of neonatal acidemia and the rate of operative intervention during labour, compared with monitoring by means of cardiotocography (CTG).
                Randomised controlled trial.
                Labour ward in tertiary-level university hospital.
                A total of 1483 women in active labour with singleton term fetus in cephalic presentation.
                Women were randomly assigned to be monitored either by STAN or by CTG. Fetal blood sampling (FBS) was optional in both groups.
                Neonatal acidemia (umbilical artery pH <7.10), neonatal metabolic acidosis (umbilical artery pH <7.05 and base excess <-12 mmol/l) and operative interventions: caesarean section rate, vacuum outlet (VO) rate and FBS rate.
                There were no statistically significant differences between the STAN group and CTG group in the incidence of neonatal acidemia (5.8 versus 4.7%) or metabolic acidosis (1.7 versus 0.7%). The caesarean section rate (6.4 versus 4.7%) and the VO rate (9.5 versus 10.7%) were also similar in the STAN and CTG groups. The incidence of FBS was lower (P < 0.001) in the STAN group (7.0%) than in the CTG group (15.6%).
                Intrapartum fetal monitoring by means of automatic STAN did not improve the neonatal outcome or decrease the caesarean section rate. However, the need for FBS during labour was lower in the STAN group. The physiology of changes in the ST waveform of the fetal electrocardiogram has been elucidated in extensive animal and human observational studies. A combination of heart rate and ST waveform analysis might improve the predictive value of intrapartum monitoring. Our purpose was to compare operative intervention and neonatal outcome in labors monitored by the conventional cardiotocogram with those monitored by ST waveform plus the cardiotocogram.
                A prospective, randomized clinical trial was performed on 2434 high-risk labors in a district general hospital in Plymouth, England. Statistical analysis was performed by Student t test and chi 2 analysis.
                There was a 46% reduction (p < 0.001, odds ratio 1.85 [1.35-2.66]) in operative deliveries for "fetal distress" and a trend to less metabolic acidosis (p = 0.09, odds ratio 0.38 [0.13-1.07]) and fewer low 5-minute Apgar scores (p = 0.12, odds ratio 0.62 [0.35-1.08]) in the ST waveform plus cardiotocogram arm.
                ST waveform analysis discriminates cardiotocogram changes in labor, and the protocol for interpretation is safe. Further randomized studies are warranted. To estimate the effectiveness of intrapartum fetal monitoring by cardiotocography plus ST analysis using a strict protocol for performance of fetal blood sampling.
                We performed a multicenter randomized trial among laboring women with a high-risk singleton pregnancy in cephalic presentation beyond 36 weeks of gestation. Participants were assigned to monitoring by cardiotocography with ST analysis (index) or cardiotocography only (control). Primary outcome was metabolic acidosis, defined as an umbilical cord artery pH below 7.05 combined with a base deficit calculated in the extracellular fluid compartment above 12 mmol/L. Secondary outcomes were metabolic acidosis in blood, operative deliveries, Apgar scores, neonatal admissions, and hypoxic-ischemic encephalopathy.
                We randomly assigned 5,681 women to the two groups (2,832 index, 2,849 control). The fetal blood sampling rate was 10.6% in the index compared with 20.4% in the control group (relative risk 0.52; 95% [CI] 0.46-0.59). The primary outcome occurred 0.7% in the index compared with 1.1% in the control group (relative risk 0.70; 95% CI 0.38-1.28; number needed to treat 252). Using metabolic acidosis calculated in blood, these rates were 1.6% and 2.6%, respectively (relative risk 0.63; 95% CI 0.42-0.94; number needed to treat 100). The number of operative deliveries, low Apgar scores, neonatal admissions, and newborns with hypoxic-ischemic encephalopathy was comparable in both groups.
                Intrapartum monitoring by cardiotocography combined with ST analysis does not significantly reduce the incidence of metabolic acidosis calculated in the extracellular fluid compartment. It does reduce the incidence of metabolic acidosis calculated in blood and the need for fetal blood sampling without affecting the Apgar score, neonatal admissions, hypoxic-ischemic encephalopathy, or operative deliveries.
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