Fetal Scalp Stimulation Versus Fetal Blood Sampling in Labour (FIRSST)

Fetal Scalp Stimulation (FSS) Versus Fetal Blood Sampling (FBS) to Assess Fetal Wellbeing in Labour - a Multi-centre Randomised Controlled Trial.

Pregnant women have routine monitoring of the baby's heart rate when in labour. Women with complicated pregnancies require continuous monitoring using an electronic recorder called a CTG. The CTG produces a paper based recording which is interpreted by the midwife as showing normal, suspicious or abnormal features of the baby's heart rate. Babies quite commonly demonstrate abnormal features from time to time during the course of labour. In some cases the abnormal features are of sufficient concern to warrant delivery by emergency caesarean section. In most of these cases the baby is born in good condition and the question arises whether the caesarean section was unnecessary. In order to reduce the chance of an unnecessary caesarean section additional "second-line" tests can be offered. One such test is where a small drop of blood is taken from the baby's scalp. This test involves an internal examination with an instrument to visualise the baby's head and a small scratch to the baby's scalp. The blood is tested for acid which is an indicator of whether or not the baby is receiving enough oxygen. The test is called a fetal blood sample or FBS. An alternative test is where the doctor or midwife performs a vaginal examination with two fingers and gently rubs the baby's scalp in an attempt to cause an increase in the baby's heart rate. This is a healthy response suggesting that the baby is receiving enough oxygen. The test is called digital fetal scalp stimulation or dFSS. These two "second-line" tests have never been compared in a properly conducted head-to-head comparison. This study aims to compare dFSS and FBS in a large clinical trial completed within four of Ireland's largest maternity hospitals. This trial will generate important evidence of direct relevance to clinical care and patient outcomes.

Study Overview

• Status: Terminated
• Conditions: Intrapartum Fetal Distress
• Intervention / Treatment: Diagnostic test: Fetal Blood Sampling (FBS); Diagnostic test: digital Fetal Scalp Stimulation (dFSS)

Detailed Description

Continuous electronic fetal heart rate recording with cardiotocography (CTG) is a standard approach to monitoring fetal wellbeing in labour and is recommended for high-risk pregnancies. The aim is to identify fetal compromise early and intervene in order to reduce serious adverse events such as cerebral palsy and perinatal death. CTG abnormalities are relatively common and can lead to the decision to deliver by emergency caesarean section. In most cases the fetus is subsequently found to have been compensating for the stress of labour and is not actually compromised. Fetal blood sampling (FBS) is a second-line invasive test that provides information on the acid-base status of the fetus, reflecting hypoxia. It is used to provide either reassurance that labour can continue, or more objective evidence that delivery needs to be expedited. Clinical guidelines in the United Kingdom and Ireland have treated FBS as a gold standard test. Recent studies have questioned the validity and reliability of FBS, and also the logistic challenges of achieving a result in a timely manner. Fetal scalp stimulation (dFSS) by digital rubbing is an alternative less invasive test of fetal wellbeing in labour and is recommended in preference to FBS in US guidelines. This research aims to compare digital FSS and FBS in women with term singleton pregnancies and an abnormal intrapartum CTG, where additional information on fetal wellbeing is required. A multi-centre randomised controlled trial will be conducted. The clinical outcomes of interest will include caesarean section, assisted vaginal birth, low Apgar scores, cord blood acidosis, and admission to the neonatal unit. This trial will generate important evidence of direct relevance to clinical care and patient outcomes.

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Ireland
  • Dublin, Ireland, D8
    • Coombe Women & Infants University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Nulliparous women
• Singleton pregnancy
• Cephalic presentation
• Gestational age 37+0 weeks or greater
• Abnormal CTG that requires second-line testing (FBS or dFSS)

Exclusion Criteria:

• Contraindication to FBS
• Limited understanding of English
• At the discretion of the responsible obstetrician in cases where there is urgency

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Fetal Blood Sampling (FBS); Fetal capillary blood samples will be collected in heparinised tubes and analysed in the delivery suite using the locally available gas analyser. The result of the first technically reliable sample, or the lowest reliable sample if multiple samples are tested, will be interpreted and acted upon according to the protocol, taking account of the clinical circumstances and the stage of labour: pH ≥7.25 normal, continue and if indicated repeat in 60 minutes; pH 7.21-7.24 borderline, repeat in 30 minutes; pH ≤ 7.20 abnormal, deliver.	Diagnostic test: Fetal Blood Sampling (FBS); Vaginal examination, insert amnioscope through cervix, visualise fetal scalp, clean fetal scalp, apply ethyl chloride spray, wipe scalp with petroleum gel, small scalp scratch with sharp instrument, collect sample in heparinised capillary tube, analyse sample.
Active Comparator: digital Fetal Scalp Stimulation (dFSS); The examiner will stimulate the fetal scalp digitally with the index and middle finger over a period of 30-60 seconds.The CTG will be observed over a 5-10 minutes interval after the dFSS and if a fetal heart rate acceleration (>15 bpm for 15 seconds) is observed the test will be considered normal. If there is an episode of normal variability (5-25 bpm) but there is no clear acceleration, the test will be considered borderline. If there is no FHR acceleration and no episode of normal variability with ongoing abnormal features, the test should be interpreted as abnormal in the same way as an abnormal FBS result. FHR acceleration normal, if indicated repeat in 60 min; Uncertain acceleration/ normal variability borderline, repeat in 30 minutes; No Acceleration/ongoing abnormal features abnormal, deliver.	Diagnostic test: digital Fetal Scalp Stimulation (dFSS); Vaginal examination, insert one or two fingers through cervix onto fetal scalp, rub fetal scalp digitally for approximately 30-60 seconds, withdraw fingers and observe CTG for 5-10 minutes.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Caesarean section (CS)	All caesarean sections will be in labour in the context of an abnormal CTG	at birth

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Caesarean section , primary indication fetal concerns	abnormal CTG, or meconium, or low pH on FBS	at birth
Caesarean section, primary indication poor progress	Poor progress in first or second stage of labour	at birth
Caesarean section, failed attempt at assisted vaginal birth	Failed vacuum or forceps in second stage of labour	at birth
Assisted vaginal birth (AVB) (all cases)	Vacuum or forceps or sequential (vacuum and forceps)	at birth
Assisted vaginal birth, primary indication fetal concerns	abnormal CTG, or meconium, or low pH on FBS	at birth
Assisted vaginal birth, primary indication poor progress	Poor progress in second stage of labour	at birth
Spontaneous Vaginal Birth (SVB)	unassisted birth	at birth
Decision Delivery Interval (DDI) for emergency CS >30 minutes	Decision delivery interval prolonged	during labour up until time of birth
Decision Delivery Interval (DDI) for AVB >15 minutes	Decision delivery interval prolonged	during labour up until time of birth
Perinatal death	intrapartum or early neonatal death	up to 7 days of age
Late perinatal death	after 7 days up to 28 days of age	8-28 days of life
Apgar score at 5 minutes <7	low Apgar score at 5 minutes	age 5 minutes
pH umbilical artery <7.00 or Base Excess artery <-12.0	arterial cord blood acidosis	immediately after birth
Admission to neonatal unit (NNU)	admission all causes	from birth up until 28 days
Neonatal encephalopathy (as defined by authors)	protocol definition	from birth up until 28 days
Therapeutic hypothermia	treatment for encephalopathy	indicated within 6 hours of birth
Abnormal neurological examination prior to discharge	clinical assessment recording abnormal findings - tone, reflexes, gag	at time of hospital discharge, assessed up to 28 days after birth
FBS related injury/complication to baby (as reported on neonatal examination)	traumatic injury or abnormal bleeding	at birth or with first 7 days of life
Major obstetric haemorrhage >1000mL	postpartum haemorrhage	up to 24 hours after birth
Obstetric Anal Sphincter Injury (OASI - all degrees)	injury either spontaneous or with episiotomy	at birth
Referral to perinatal mental health services	psychological symptoms warranting referral	from birth up to six weeks after birth
Maternal acceptability of procedure (defined by questionnaire)	acceptability	from birth up to 7 days after birth
Number of second-line tests (dFSS or FBS)	each event (rather than samples taken)	during labour up until birth
Number of inconclusive/uninterpretable dFSS procedures	no clear acceleration or variability borderline	during labour up until birth
Number of failed FBS procedures	no sample or reliable result achieved	during labour up until birth

Collaborators and Investigators

• Sponsor: University of Dublin, Trinity College
• Collaborators: National University of Ireland, Galway, Ireland; Royal College of Surgeons, Ireland; University of Limerick; University College Cork; Health Research Board, Ireland; Health Research Board - Trials Methodology Research Network
• Investigators: Principal Investigator: Deirdre J Murphy, MD, Trinity College, University of Dublin

Publications and helpful links

General Publications

• Hughes O, Murphy DJ. Comparing second-line tests to assess fetal wellbeing in Labor: a feasibility study and pilot randomized controlled trial. J Matern Fetal Neonatal Med. 2022 Jan;35(1):91-99. doi: 10.1080/14767058.2020.1712704. Epub 2020 Jan 12.
• Murphy DJ, Shahabuddin Y, Yambasu S, O'Donoghue K, Devane D, Cotter A, Gaffney G, Burke LA, Molloy EJ, Boland F. Digital fetal scalp stimulation (dFSS) versus fetal blood sampling (FBS) to assess fetal wellbeing in labour-a multi-centre randomised controlled trial: Fetal Intrapartum Randomised Scalp Stimulation Trial (FIRSST NCT05306756). Trials. 2022 Oct 4;23(1):848. doi: 10.1186/s13063-022-06794-9.

Study record dates

Study Major Dates

• Study Start (Actual): May 10, 2022
• Primary Completion (Actual): May 1, 2023
• Study Completion (Actual): August 31, 2023

Study Registration Dates

• First Submitted: March 14, 2022
• First Submitted That Met QC Criteria: March 22, 2022
• First Posted (Actual): April 1, 2022

Study Record Updates

• Last Update Posted (Actual): February 20, 2024
• Last Update Submitted That Met QC Criteria: February 15, 2024
• Last Verified: February 1, 2024

More Information

Terms related to this study

• Keywords: caesarean section; randomised controlled trial; cardiotocography; fetal blood sampling; fetal scalp stimulation
• Additional Relevant MeSH Terms: Fetal Distress
• Other Study ID Numbers: DIFA019

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Subject to request to PI

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No