Contact information
Type
Scientific
Primary contact
Prof G.H.A. Visser
ORCID ID
Contact details
University Medical Centre Utrecht
Department of Obstetrics
P.O. Box 85500
Utrecht
3508 GA
Netherlands
+31 (0)30 250 6426
g.h.a.visser@azu.nl
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
NTR174
Study information
Scientific title
Acronym
STAN versus CTG + FBS
Study hypothesis
Cardiotocography (CTG) is worldwide the method for foetal surveillance during labour. However, CTG alone shows many false positive results and without foetal blood sampling (FBS) it results in an increase in operative deliveries without an improvement of foetal outcome. FBS requires additional expertise, is invasive and has often to be repeated during labour. Two randomised controlled trials have shown that a combination of CTG and non-invasive ST-analysis (of the foetal electrocardiogram [ECG]) reduces the rates of metabolic acidosis and instrumental delivery. However, in both randomised controlled trials FBS was still performed in both arms, 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.
Hypothesis:
Intrapartum foetal monitoring with the STAN-method (cardiotocograpy with ST-analysis of the foetal ECG) results in less neonates with metabolic acidosis and less interventions for foetal distress as compared to monitoring with cardiotocography in combination with foetal blood sampling.
As of 16/07/2007 the power calculation was changed, and the target number of participants was increased from 2400 to 5100; see interventions section for more details.
Ethics approval
Medical Ethics Committee University Medical Centre Utrecht, 17/11/2005, ref: 05/157-K
Study design
Randomised active controlled parallel-group multicentre trial
Primary study design
Interventional
Secondary study design
Randomised controlled trial
Trial setting
Hospitals
Trial type
Screening
Patient information sheet
Condition
Women in labour with a high-risk pregnancy
Intervention
Women will be randomly assigned to routine care including foetal monitoring by cardiotocography with foetal blood sampling (CTG + FBS group) or to the index group including cardiotocography with ST-analysis (CTG + ST group). Clinical management in the CTG + FBS group (routine care) will be guided by guidelines produced by the International Federation of Gynaecology and Obstetrics (FIGO). FBS is recommended in case of a suboptimal or abnormal CTG pattern. In cases with scalp blood pH lower than 7.20 or preterminal cardiotocograms delivery is recommended. In the CTG + ST group, clinical management will be supported by computerised ST waveform assessment and will be guided by the STAN-guidelines, indicating when intervention is recommended. In case of poor signal quality of the foetal ECG-signal it is allowed to perform a FBS in the first stage of labour. From each woman, we will systematically (by protocol) document demographics and medical history, as well as CTG analysis, foetal ST-analysis and FBS results. Finally, the umbilical cord artery results, the performance of an instrumental delivery and neonatal outcome until discharge from the hospital will be documented.
CTG and FBS:
In women randomised to the control group, a scalp electrode will be applied to the foetal head and connected to the conventional CTG-monitor conform routine practice of CTG monitoring. If the pH of the first measurement is below 7,20 delivery is recommended unless the cause of foetal distress can be alleviated. If the pH is between 7,20 and 7,25 FBS will be repeated after 30 minutes. If the pH is above 7,25 FBS is repeated according to CTG pattern according to the attending doctor or midwife. The number of failed FBS will be recorded.
CTG and ST-analysis:
In women randomised to the index group, a scalp electrode will be applied to the foetal head and connected to the STAN-monitor conform routine practice of CTG monitoring. This electrode will allow both standard foetal heart rate monitoring (CTG) as well as ST-analysis. The CTG will be classified as normal, intermediate, abnormal or preterminal according to the FIGO-guidelines for foetal heart rate monitoring. The ST log automatically alerts the attending doctor or midwife if a significant ST-event occurs. Delivery is recommended when there are significant ST-changes unless the cause of foetal distress can be alleviated. It is only allowed to perform FBS in the CTG + ST-analysis arm in case of poor signal quality of the foetal ECG in combination with an intermediate or abnormal foetal heart rate pattern in the first stage.
Power calculation information added as of 16/07/2007:
The sample size calculation is based on the primary endpoint, which is metabolic acidosis in the umbilical cord artery.
Although in the two randomised trials the incidence of metabolic acidosis decreased from 1.5% to 0.5% in favour of the CTG + ST-analysis group, we assume that the incidence of metabolic acidosis in our higher-risk population (women delivering in the hospital with a medical indication) is higher and estimated on 3.5%, as found in our preliminary study. Based upon the numbers of the largest clinical trial with a relative risk of 0.5 the required sample size would then yield 2400 cases (1200 per arm), using an alpha of 0.05 (2-sided) and a power of 0.80. However, soon after the start of our study a third randomised clinical trial appeared, although much smaller and non-significant, but yielding an opposite effect . A meta-analysis of the three clinical trials showed the varying relative risks of 0.5, 0.4 and 2.4. Hence, to be conservative we used the meta-analysis overall relative risk of 0.6 for our power calculation, implying a reduction of metabolic acidosis, in favour of ST-analysis, from 3.5% to 2.1%. With an alpha of 0.05, a two-sided test (given conflicting results in the literature) and a power of 0.80, about 4638 women should be randomised (2319 per arm). Accounting for 10% loss to follow-up, the study requires inclusion of about 5100 women in order to obtain 4638 analysable cases.
As of 06/01/2009 this record was amended to include the following information: The inclusion of participants for this trial is complete.
Intervention type
Other
Phase
Not Applicable
Drug names
Primary outcome measures
Presence or absence of metabolic acidosis defined as a pH less than 7.05 and a BDecf greater than 12 mmol/l in the umbilical cord artery.
There are no interim analyses, only by the data safety monitorings committee for serious adverse events.
Secondary outcome measures
1. Instrumental delivery rate for the following indications: foetal distress, failure to progress or a combination of these
2. Cost-effectiveness of both strategies: the ratio of incremental costs and the reduced rate of metabolic acidosis, associated with the strategies
3. Neonatal outcome defined by low Apgar scores, defined as less than four after one minute and/or less than seven after five minutes
4. Need for admission to the neonatal medium or intensive care unit
5. Cost-effectiveness of both monitoring strategies across hospitals, particularly, comparing academic and non-academic hospitals
There are no interim analyses, only by the data safety monitorings committee for serious adverse events.
Overall trial start date
01/04/2006
Overall trial end date
01/04/2009
Reason abandoned
Eligibility
Participant inclusion criteria
1. Women in labour
2. Singleton foetus in vertex position
3. Gestational age more than 35 + 6 weeks of gestation
4. Indication for electronic foetal monitoring (CTG)
Participant type
Patient
Age group
Adult
Gender
Female
Target number of participants
5100
Participant exclusion criteria
1. Women with a foetus in breech position
2. Women with twin pregnancy
3. No informed consent
Recruitment start date
01/04/2006
Recruitment end date
01/04/2009
Locations
Countries of recruitment
Netherlands
Trial participating centre
University Medical Centre Utrecht
Utrecht
3508 GA
Netherlands
Sponsor information
Organisation
University Medical Centre Utrecht (UMCU) (Netherlands)
Sponsor details
P.O. Box 85500
Utrecht
3508 GA
Netherlands
Sponsor type
University/education
Website
Funders
Funder type
Research organisation
Funder name
The Netherlands Organisation for Health Research and Development (ZonMw) (Netherlands)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Results - basic reporting
Publication summary
1. 2007 protocol in http://www.ncbi.nlm.nih.gov/pubmed/17655764
2. 2010 results in http://www.ncbi.nlm.nih.gov/pubmed/20502287
3. 2012 results in http://www.ncbi.nlm.nih.gov/pubmed/22568406
Publication citations
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Results
Westerhuis ME, Visser GH, Moons KG, van Beek E, Benders MJ, Bijvoet SM, van Dessel HJ, Drogtrop AP, van Geijn HP, Graziosi GC, Groenendaal F, van Lith JM, Nijhuis JG, Oei SG, Oosterbaan HP, Porath MM, Rijnders RJ, Schuitemaker NW, Sopacua LM, van der Tweel I, Wijnberger LD, Willekes C, Zuithoff NP, Mol BW, Kwee A, Cardiotocography plus ST analysis of fetal electrocardiogram compared with cardiotocography only for intrapartum monitoring: a randomized controlled trial., Obstet Gynecol, 2010, 115, 6, 1173-1180, doi: 10.1097/AOG.0b013e3181dfffd6.
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Results
Schuit E, Kwee A, Westerhuis ME, Van Dessel HJ, Graziosi GC, Van Lith JM, Nijhuis JG, Oei SG, Oosterbaan HP, Schuitemaker NW, Wouters MG, Visser GH, Mol BW, Moons KG, Groenwold RH, A clinical prediction model to assess the risk of operative delivery., BJOG, 2012, 119, 8, 915-923, doi: 10.1111/j.1471-0528.2012.03334.x.
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Westerhuis ME, Moons KG, van Beek E, Bijvoet SM, Drogtrop AP, van Geijn HP, van Lith JM, Mol BW, Nijhuis JG, Oei SG, Porath MM, Rijnders RJ, Schuitemaker NW, van der Tweel I, Visser GH, Willekes C, Kwee A, A randomised clinical trial on cardiotocography plus fetal blood sampling versus cardiotocography plus ST-analysis of the fetal electrocardiogram (STAN) for intrapartum monitoring., BMC Pregnancy Childbirth, 2007, 7, 13, doi: 10.1186/1471-2393-7-13.