Michelle E.M.H. Westerhuis

Cardiotocography plus ST analysis of fetal electrocardiogram compared with cardiotocography only for intrapartum monitoring: a randomized controlled trial

OBJECTIVE: To estimate the effectiveness of intrapartum fetal monitoring by cardiotocography plus ST analysis using a strict protocol for performance of fetal blood sampling. METHODS: 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. RESULTS: 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. CONCLUSION: 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. CLINICAL TRIAL REGISTRATION: ISRCTN Register, www.isrctn.org, ISRCTN95732366. LEVEL OF EVIDENCE: I

ST Analysis of the Fetal Electrocardiogram in Intrapartum Fetal Monitoring: A Meta-Analysis.

OBJECTIVE: To compare the effects of ST-waveform analysis in combination with cardiotocography with conventional cardiotocography for intrapartum fetal monitoring. DATA SOURCES: We searched MEDLINE, Embase, and PubMed for randomized controlled trials (RCTs) evaluating ST-waveform analysis for intrapartum fetal monitoring. METHODS OF STUDY SELECTION: We identified RCTs that compared ST-waveform analysis and conventional cardiotocography for intrapartum fetal monitoring of singleton pregnancies in cephalic presentation beyond 34 weeks of gestation and evaluating at least one of the following: metabolic acidosis, umbilical cord pH less than 7.15, umbilical cord pH less than 7.10, umbilical cord pH less than 7.05, umbilical cord pH less than 7.00, Apgar scores less than 7 at 5 minutes, admittance to the neonatal intensive care unit, need for intubation, presence of hypoxic ischemic encephalopathy, perinatal death, operative delivery, and number of fetal blood samplings. TABULATION, INTEGRATION, AND RESULTS: Five RCTs, which included 15,352 patients, met the selection criteria. Random-effects models were used to estimate the combined relative risks (RRs) of ST analysis compared with conventional cardiotocography. Compared with conventional cardiotocography, ST analysis showed a nonsignificant reduction in metabolic acidosis (RR 0.72, 95% confidence interval 0.43–1.19, number needed to treat [NNT] 357). ST analysis significantly reduced the incidence of additional fetal blood sampling (RR 0.59, 95% confidence interval 0.44–0.79, NNT 11), operative vaginal deliveries (RR 0.88, 95% confidence interval 0.80–0.97, NNT 64), and total operative deliveries (RR 0.94, 95% confidence interval 0.89–0.99, NNT 64). For other outcomes, no differences in effect were seen between ST analysis and conventional cardiotocography, or data were not suitable for meta-analysis. CONCLUSION: The additional use of ST analysis for intrapartum monitoring reduced the incidence of operative vaginal deliveries and the need for fetal blood sampling but did not reduce the incidence of metabolic acidosis at birth.

Effectiveness of electronic fetal monitoring with additional ST analysis in vertex singleton pregnancies at >36 weeks of gestation: an individual participant data metaanalysis

OBJECTIVE The purpose of this study was to assess the effectiveness of electronic fetal monitoring (EFM) alone and with additional ST analysis (EFM + ST) in laboring women with a singleton term pregnancy that is in cephalic presentation in the prevention of metabolic acidosis by the application of individual patient data metaanalysis. STUDY DESIGN We conducted an individual patient data metaanalysis using data from 4 randomized trials, which enabled us to account for missing data and investigate relevant subgroups. The primary outcome was metabolic acidosis, which was defined as an umbilical cord-artery pH <7.05 and a base deficit that had been calculated in the extra cellular fluid compartment >12 mmol/L. We performed 8 explanatory subgroup analyses for 8 different endpoints. RESULTS We analyzed data from 12,987 women and their newborn infants. Metabolic acidosis was present in 57 women (0.9%) in the EFM + ST group and 73 women (1.1%) in the EFM alone group (relative risk [RR], 0.76; 95% CI, 0.53-1.10). Compared with EFM alone, the use of EFM + ST resulted in a reduction in the frequency of instrumental vaginal deliveries (RR, 0.90; 95% CI, 0.83-0.99) and fetal blood samples (RR, 0.49; 95% CI, 0.44-0.55). Cesarean delivery rates were comparable between both groups (RR, 0.99; 95% CI, 0.91-1.09). Subgroup analyses showed that EFM + ST resulted in fewer admissions to a neonatal intensive care unit for women with a duration of pregnancy of >41 weeks (RR, 0.61; 95% CI, 0.39-0.95). CONCLUSION EFM + ST does not reduce the risk of metabolic acidosis, but it does reduce the need for instrumental vaginal deliveries and fetal blood sampling.

A randomised clinical trial on cardiotocography plus fetal blood sampling versus cardiotocography plus ST-analysis of the fetal electrocardiogram (STAN®) for intrapartum monitoring

BackgroundCardiotocography (CTG) is worldwide the method for fetal surveillance during labour. However, CTG alone shows many false positive test results and without fetal blood sampling (FBS), it results in an increase in operative deliveries without improvement of fetal outcome. FBS requires additional expertise, is invasive and has often to be repeated during labour. Two clinical trials have shown that a combination of CTG and ST-analysis of the fetal electrocardiogram (ECG) reduces the rates of metabolic acidosis and instrumental delivery. However, in both trials FBS was still performed in the ST-analysis arm, and it is therefore still unknown if the observed results were indeed due to the ST-analysis or to the use of FBS in combination with ST-analysis.Methods/DesignWe aim to evaluate the effectiveness of non-invasive monitoring (CTG + ST-analysis) as compared to normal care (CTG + FBS), in a multicentre randomised clinical trial setting. Secondary aims are: 1) to judge whether ST-analysis of fetal electrocardiogram can significantly decrease frequency of performance of FBS or even replace it; 2) perform a cost analysis to establish the economic impact of the two treatment options.Women in labour with a gestational age ≥ 36 weeks and an indication for CTG-monitoring can be included in the trial.Eligible women will be randomised for fetal surveillance with CTG and, if necessary, FBS or CTG combined with ST-analysis of the fetal ECG.The primary outcome of the study is the incidence of serious metabolic acidosis (defined as pH < 7.05 and Bdecf > 12 mmol/L in the umbilical cord artery). Secondary outcome measures are: instrumental delivery, neonatal outcome (Apgar score, admission to a neonatal ward), incidence of performance of FBS in both arms and cost-effectiveness of both monitoring strategies across hospitals.The analysis will follow the intention to treat principle. The incidence of metabolic acidosis will be compared across both groups. Assuming a reduction of metabolic acidosis from 3.5% to 2.1 %, using a two-sided test with an alpha of 0.05 and a power of 0.80, in favour of CTG plus ST-analysis, about 5100 women have to be randomised. Furthermore, the cost-effectiveness of CTG and ST-analysis as compared to CTG and FBS will be studied.DiscussionThis study will provide data about the use of intrapartum ST-analysis with a strict protocol for performance of FBS to limit its incidence. We aim to clarify to what extent intrapartum ST-analysis can be used without the performance of FBS and in which cases FBS is still needed.Trial Registration NumberISRCTN95732366

Cost-effectiveness of cardiotocography plus ST analysis of the fetal electrocardiogram compared with cardiotocography only

Objective. To assess the cost‐effectiveness of addition of ST analysis of the fetal electrocardiogram (ECG; STAN®) to cardiotocography (CTG) for fetal surveillance during labor compared with CTG only. Design. Cost‐effectiveness analysis based on a randomized clinical trial on ST analysis of the fetal ECG. Setting. Obstetric departments of three academic and six general hospitals in The Netherlands. Population. Laboring women with a singleton high‐risk pregnancy, a fetus in cephalic presentation, a gestational age >36weeks and an indication for internal electronic fetal monitoring. Methods. A trial‐based cost‐effectiveness analysis was performed from a health‐care provider perspective. Main Outcome Measures. Primary health outcome was the incidence of metabolic acidosis measured in the umbilical artery. Direct medical costs were estimated from start of labor to childbirth. Cost‐effectiveness was expressed as costs to prevent one case of metabolic acidosis. Results. The incidence of metabolic acidosis was 0.7% in the ST‐analysis group and 1.0% in the CTG‐only group (relative risk 0.70; 95% confidence interval 0.38–1.28). Per delivery, the mean costs per patient of CTG plus ST analysis (n= 2 827) were €1 345 vs. €1 316 for CTG only (n= 2 840), with a mean difference of €29 (95% confidence interval −€9 to €77) until childbirth. The incremental costs of ST analysis to prevent one case of metabolic acidosis were €9 667. Conclusions. The additional costs of monitoring by ST analysis of the fetal ECG are very limited when compared with monitoring by CTG only and very low compared with the total costs of delivery.

Cerebrospinal fluid leakage, an uncommon complication of fetal blood sampling: a case report and review of the literature.

In a recently published randomized clinical trial on intrapartum fetal monitoring, fetal blood samples were obtained in 879 women. One serious complication of fetal blood sampling (FBS) was reported, a case in which physical examination of the neonate after delivery revealed clear fluid loss from the incision site. Four layers of the scalp appeared to be incised. The subarachnoid space was closed with 2 sutures, and antibiotics were started due to the risk of meningitis. The patient was discharged in good clinical condition. In this article, the case is presented and the literature reviewed. We found 12 articles reporting 37 cases of a complication due to FBS, none concerning leakage of cerebrospinal fluid. In conclusion, complications of FBS are rare but can be serious. Excessive fetal bleeding is most frequently reported and often associated with an underlying coagulopathy in the neonate. Target Audience: Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this educational activity, the obstetrician/gynecologist should be better able to assess the chance of possible complications due to fetal blood sampling; select fetuses at risk for complications due to fetal blood sampling; and evaluate certain technical precautions when performing this procedure.

Prediction of Neonatal Metabolic Acidosis in Women with a Singleton Term Pregnancy in Cephalic Presentation

We sought to predict neonatal metabolic acidosis at birth using antepartum obstetric characteristics (model 1) and additional characteristics available during labor (model 2). In 5667 laboring women from a multicenter randomized trial that had a high-risk singleton pregnancy in cephalic presentation beyond 36 weeks of gestation, we predicted neonatal metabolic acidosis. Based on literature and clinical reasoning, we selected both antepartum characteristics and characteristics that became available during labor. After univariable analyses, the predictors of the multivariable models were identified by backward stepwise selection in a logistic regression analysis. Model performance was assessed by discrimination and calibration. To correct for potential overfitting, we (internally) validated the models with bootstrapping techniques. Of 5667 neonates born alive, 107 (1.9%) had metabolic acidosis. Antepartum predictors of metabolic acidosis were gestational age, nulliparity, previous cesarean delivery, and maternal diabetes. Additional intrapartum predictors were spontaneous onset of labor and meconium-stained amniotic fluid. Calibration and discrimination were acceptable for both models (c-statistic 0.64 and 0.66, respectively). In women with a high-risk singleton term pregnancy in cephalic presentation, we identified antepartum and intrapartum factors that predict neonatal metabolic acidosis at birth.

Identification of cases with adverse neonatal outcome monitored by cardiotocography versus ST analysis: secondary analysis of a randomized trial

Objective. To evaluate whether correct adherence to clinical guidelines might have led to prevention of cases with adverse neonatal outcome. Design. Secondary analysis of cases with adverse outcome in a multicenter randomized clinical trial. Setting. Nine Dutch hospitals. Population. Pregnant women with a term singleton fetus in cephalic position. Methods. Data were obtained from a randomized trial that compared monitoring by STAN® (index group) with cardiotocography (control group). In both trial arms, three observers independently assessed the fetal surveillance results in all cases with adverse neonatal outcome, to determine whether an indication for intervention was present, based on current clinical guidelines. Main outcome measures. Adverse neonatal outcome cases fulfilled one or more of the following criteria: (i) metabolic acidosis in umbilical cord artery (pH < 7.05 and base deficit in extracellular fluid >12 mmol/L); (ii) umbilical cord artery pH < 7.00; (iii) perinatal death; and/or (iv) signs of moderate or severe hypoxic ischemic encephalopathy. Results. We studied 5681 women, of whom 61 (1.1%) had an adverse outcome (26 index; 35 control). In these women, the number of performed operative deliveries for fetal distress was 18 (69.2%) and 16 (45.7%), respectively. Reassessment of all 61 cases showed that there was a fetal indication to intervene in 23 (88.5%) and 19 (57.6%) cases, respectively. In 13 (50.0%) vs. 11 (33.3%) cases, respectively, this indication occurred more than 20 min before the time of delivery, meaning that these adverse outcomes could possibly have been prevented. Conclusions. In our trial, more strict adherence to clinical guidelines could have led to additional identification and prevention of adverse outcome.

Predictive value of the baseline T-QRS ratio of the fetal electrocardiogram in intrapartum fetal monitoring: a prospective cohort study

Objective. To evaluate the added value of the baseline T/QRS ratio to other known risk factors in predicting adverse outcome and interventions for suspected fetal distress. Design. Prospective cohort study. Setting. Three academic and six non‐academic teaching hospitals in the Netherlands. Population. Laboring women with a high‐risk cephalic singleton pregnancy beyond 36 weeks of gestation. Methods. We obtained STAN® recordings (ST‐analysis, Neoventa, Sweden) from two previous studies. Three patient groups were defined: cases with adverse outcome, cases with emergency delivery because of suspected fetal distress without adverse outcome, and a reference group of uncomplicated cases. Baseline T/QRS ratios among the adverse outcome and intervention for suspected fetal distress cases were compared to those of the uncomplicated cases. The ability of baseline T/QRS to predict adverse outcome and suspected fetal distress was determined using a multivariable logistic model. Main outcome measures. The added value of the baseline T/QRS to other known risk factors in the prediction of adverse outcome and interventions for suspected fetal distress. Results. From 3462 recordings, 2459 were available for analysis. Median baseline T/QRS for uncomplicated cases, adverse outcome and interventions for suspected fetal distress were 0.12 (range 0.00–0.52), 0.12 (0.00–0.42) and 0.13 (0.00–0.39), respectively. There was no statistical difference between these groups. Multivariable analysis showed no added value of baseline T/QRS in the prediction of either adverse outcome or interventions for suspected fetal distress. Conclusion. Baseline T/QRS has no added value in the prediction of adverse neonatal outcome or interventions for suspected fetal distress.

Substandard care in delivery‐related asphyxia among term infants: prospective cohort study

Objective. To assess substandard care factors in the case of delivery‐related asphyxia. Design. Prospective cohort study. Setting. Catchment area of the Neonatal Intensive Care Unit (NICU) of the University Medical Center Utrecht; a region in the middle of the Netherlands covering 13% of the Dutch population. Population. Term infants, without congenital malformations, who died intrapartum or were admitted to the Neonatal Intensive Care Unit due to asphyxia. Methods. During a two‐year period, cases were prospectively collected and audited by an expert panel. Main outcome measures. Substandard care factors. Results. 37 735 term infants without congenital malformations were born. There were 19 intrapartum deaths, and 89 NICU admissions of which 12 neonates died. In 63 (58%) cases a substandard care factor was identified that was possibly (n= 47, 43%) or probably (n= 16, 15%) related to perinatal death or NICU admission. In primary care, substandard care factors were mainly the low frequency of examination during labor and delay in referral to secondary care. In secondary care, misinterpretation of cardiotocography and failure to respond adequately to clinical signs of fetal distress were the most common substandard care factors. Conclusions. Substandard care is present in a substantial number of cases with delivery‐related asphyxia resulting in perinatal death or NICU admission. Improving the organization of obstetric care in the Netherlands as well as training of obstetric caregivers might reduce adverse outcomes.