An interventional study of Ultrasound in Labor Pain, sponsored by Samuel Lunenfeld Research Institute, Mount Sinai Hospital. Recruiting at 1 site in Canada. Open to female participants aged 18 Years to 50 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-07-11.
Sponsored by Samuel Lunenfeld Research Institute, Mount Sinai Hospital · Not applicable, Interventional, and Diagnostic
Combined spinal-epidural (CSE) for labor analgesia has been used for many years and is practiced commonly at our institution, especially when the patient requests immediate pain relief. CSE is not only beneficial for its faster onset of analgesia, but also it is favorable in relation to the need for rescue analgesia, urinary retention, and rate of instrumental delivery compared to the traditional epidural. Despite its beneficial effects, there is a risk of about 15-30% of developing abnormal fetal heart rate following CSE. This is self-resolving with minimal or no intervention. Although the cause of fetal bradycardia is not fully elucidated, variations in uterine artery blood flow after epidural analgesia are thought to be due to the interaction of numerous events related to blockade of sympathetic innervations, fluid administration, maternal hypotension, uterine vascular effects of sympathetic block, fluctuations in circulating catecholamines, and possibly the effect of opioids. Similar mechanism is thought to be a cause of fetal bradycardia after the CSE with its faster onset and superior block.
Maternal or fetal circulation during labor can be assessed using continuous-wave Doppler ultrasound to monitor maternal uterine artery (UtA) and fetal umbilical artery (UmA) velocity waveforms to detect changes in blood flow. The velocimetry indices mentioned above have been often used to assess the changes in the blood flow before and after the induction of epidural analgesia during labor in several studies. Although there are some studies regarding the effect of labor epidural analgesia using velocimetry indices, but there is currently no published study evaluating velocimetry indices of uterine and umbilical arteries before and after the induction of CSE. Thus, the aim of this study is to investigate the impact of CSE to maternal and fetal blood flow to evaluate the relationships.
The investigators hypothesize that both uterine artery and umbilical artery blood flow are reduced after the induction of CSE, which may be responsible for the occurrence of fetal bradycardia.
396 studies on the registry are indexed under Labor Pain; 66 are open to participants now.
This study's planned enrollment of 54 is below the median of 100 across 326 interventional studies indexed under Labor Pain.
Browse Labor Pain studies →Samuel Lunenfeld Research Institute, Mount Sinai Hospital is the lead sponsor of 135 studies on the registry; 17 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Ultrasound will be used to measure velocimetric index of the umbilical artery.
Device: Ultrasound
Ultrasound will be used to measure velocimetric index of the umbilical artery.
Device: Ultrasound
Ultrasound scan of the umbilical artery
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 10 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 10 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 10 minutes
Umbilical artery velocimetric index - pulsatility index (PI) at 10 minutes
Umbilical artery velocimetric index - pulsatility index (PI) will be measured 10 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 10 minutes
Umbilical artery velocimetric index - resistance index (RI) at 10 minutes
Umbilical artery velocimetric index - resistance index (RI) will be measured 10 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 10 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at baseline
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured prior to combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 5 minutes
Umbilical artery velocimetric index - pulsatility index (PI) at baseline
Umbilical artery velocimetric index - pulsatility index (PI) will be measured prior to combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 5 minutes
Umbilical artery velocimetric index - resistance index (RI) at baseline
Umbilical artery velocimetric index - resistance index (RI) will be measured prior to combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 5 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 5 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 5 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 5 minutes
Umbilical artery velocimetric index - pulsatility index (PI) at 5 minutes
Umbilical artery velocimetric index - pulsatility index (PI)will be measured 5 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 5 minutes
Umbilical artery velocimetric index - resistance index (RI) at 5 minutes
Umbilical artery velocimetric index - resistance index (RI) will be measured 5 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 5 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 20 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 20 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 20 minutes
Umbilical artery velocimetric index - pulsatility index (PI) at 20 minutes
Umbilical artery velocimetric index - pulsatility index (PI) will be measured 20 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 20 minutes
Umbilical artery velocimetric index - resistance index (RI) at 20 minutes
Umbilical artery velocimetric index - resistance index (RI) will be measured 20 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 20 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 30 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 30 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 5 minutes
Umbilical artery velocimetric index - pulsatility index (PI) at 30 minutes
Umbilical artery velocimetric index - pulsatility index (PI) will be measured 30 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 30 minutes
Umbilical artery velocimetric index - resistance index (RI) at 30 minutes
Umbilical artery velocimetric index - resistance index (RI) will be measured 30 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.
Time frame: 30 minutes
Pain score at baseline - questionnaire
Pain score - verbal numeric rating scale (0-10) prior to combined spinal epidural
Time frame: 1 minute
Pain score at 10 minutes - questionnaire
Pain score - verbal numeric rating scale (0-10) at 10 minute after combined spinal epidural
Time frame: 10 minutes
Pain score at 30 minutes - questionnaire
Pain score - verbal numeric rating scale (0-10) at 30 minute3 after combined spinal epidural
Time frame: 30 minutes
Sensory block level at 10 minutes
Sensory block level at 10 minutes following combined spinal epidural
Time frame: 10 minutes
Sensory block level at 30 minutes
Sensory block level at 30 minutes following combined spinal epidural
Time frame: 30 minutes
frequency of uterine contractions
The number of contractions on the monitor in a 10 minute period.
Time frame: 10 minutes
Presence of prolonged hypertonic uterine contractions- questionnaire
Presence of prolonged hypertonic uterine contractions as measured by the monitor
Time frame: 30 minutes
Hypotension: systolic blood pressure less than 80% of baseline
Systolic blood pressure \< 80% of baseline, monitored q5 for 30 minutes following combined spinal epidural
Time frame: 30 minutes
Hypertension: systolic blood pressure greater than 120% of baseline
Systolic blood pressure \> 120% of baseline, monitored q5 for 30 minutes following combined spinal epidural
Time frame: 30 minutes
Bradycardia: heart rate less than 70% of baseline
Heart rate \< 70% of baseline or a heart rate \< 50bpm, monitored q5 for 30 minutes following combined spinal epidural
Time frame: 30 minutes
Desaturation: oxygen level <95%
Oxygen level \<95%, monitored q5 for 30 minutes following combined spinal epidural
Time frame: 30 minutes
fetal heart rate at baseline
fetal heart rate at baseline, prior to combined spinal epidural
Time frame: 5 minutes
fetal heart rate q5 min up to 30 minutes
fetal heart rate q5 min up to 30 minutes following combined spinal epidural
Time frame: 30 minutes
presence of fetal bradycardia - questionnaire
presence of fetal bradycardia (fetal heart rate \<110)
Time frame: 30 minutes
presence of fetal prolonged deceleration - questionnaire
presence of fetal prolonged deceleration (fetal heart rate \<110/min lasting less than 10 minutes)
Time frame: 30 minutes
presence of fetal persistent late decelerations - questionnaire
presence of fetal persistent late decelerations will be recorded
Time frame: 30 minutes
presence of fetal non-reassuring variable deceleration - questionnaire
presence of fetal non-reassuring variable deceleration will be recorded
Time frame: 30 minutes
presence of fetal salutatory variability - questionnaire
presence of fetal salutatory variability (FHR change\>25beats) will be recorded
Time frame: 30 minutes
Neonatal weight
Neonatal weight measured after delivery in grams minutes
Time frame: up to 24 hours
Apgar score at 1 minute
Apgar score at 1 minute
Time frame: 1 minute
Apgar score at 5 minutes
Apgar score at 5 minutes
Time frame: 5 minutes
Mode of delivery - questionnaire
Mode of delivery will be recorded as vaginal, assisted (forceps or vacuum), or cesarean
Time frame: up to 24 hours
Plan to share: No
No publications or documents are linked to this record.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Samuel Lunenfeld Research Institute, Mount Sinai Hospital