During pregnancy, unique blood vessels form within the uterine wall, known as spiral arteries. These vessels originate from the uterine artery, which is the main artery supplying blood to the uterus. Throughout pregnancy, spiral arteries undergo significant changes to increase blood and oxygen flow to the placenta, ensuring the developing baby receives adequate nutrients. When these arteries fail to remodel properly, complications such as pre-eclampsia or fetal growth restriction can occur.
Until now, direct observation and evaluation of spiral arteries during pregnancy has not been feasible. Contrast-enhanced ultrasound may provide a breakthrough in this area. In this study, the investigators aim to use this imaging technique to visualize spiral arteries after the placenta has been delivered. If successful, this could allow to assess their structural quality. Additionally, the investigators will employ ultrasound to monitor physiological changes in the uterine artery during late pregnancy (after 37 weeks), during labour, and postpartum.
By conducting these measurements, the investigators hope to develop methods for detecting spiral artery abnormalities earlier in pregnancy. Early identification could enable timely interventions and help prevent severe complications.
Pregnant patient at a minimum age of 18 years
Singleton pregnancy at term (≥37 weeks gestation)
Planning to deliver at the Máxima Medical Centre
Able to provide informed consent
Multiple gestation pregnancy
Contra-indications to CEUS, e.g. known allergy for constituents of SonoVue™
Planning on breastfeeding
Medical emergency during or after delivery, which makes CEUS impossible or undesirable
Single group
SonoVue (sulphur hexafluoride microbubbles)
Diagnostic testSonoVue will be used in this study as ultrasound contrast agents for contrast enhanced ultrasound to assess the feasibility in visualizing and charactering the persistence of maternal uterine spiral arteries within 4 hours postpartum.
Number of participants with persisting spiral arteries detected by contrast enhanced ultrasound within 4 hours postpartum.
Presence of persisting spiral arteries will be assessed using contrast enhanced ultrasound (CEUS) with Sonovue within 4 hours postpartum. The transition of spiral arteries into the intervillous space will be identified at the interface between the decidua and the basal plate of the placenta. Depending on placental location, a sagittal or coronal plane will be selected for optimal visualization. The probe will be positioned perpendicular (90°) to the uteroplacental interface, and color Doppler will be activated to confirm unidirectional flow at the spiral artery opening. Persistence of spiral arteries will be determined as a dichotomous outcome. Visbile or not visible. The number of patients will be calculated in whom the result was: visible.
Feasibility of Contrast Enhanced Ultrasound (CEUS) with Sonovue for visualizing spiral arteries within 4 hours postpartum. Dichotomous outcome; visible or invisible spiral arteries.
Feasibility will be assessed by determining whether CEUS with Sonovue successfully visualizes and characterizes maternal uterine spiral arteries within 4 hours postpartum. A scan will be considered feasible if the transition of spiral arteries into the intervillous space can be identified at the uteroplacental interface using the predefined imaging protocol (correct probe orientation, sagittal/coronal plane selection, and confirmation of unidirectional flow with color Doppler). The outcome is dichotomous. The spiral arteries are visible or not visible.
Change in uterine artery Resistance Index (RI) across peripartum period
Uterine artery resistance index (RI) will be measured using Doppler ultrasound before delivery (after 37 weeks) Uterine artery resistance index (RI) will be measured using Doppler ultrasound during delivery (active labor or same day prior to cesarean) Uterine artery resistance index (RI) will be measured using Doppler ultrasound within 4 hours postpartum.
Change in uterine artery Pulsatility Index (PI) across peripartum period
Uterine artery pulsatility index (PI) will be measured using Doppler ultrasound before delivery (after 37 weeks), Uterine artery pulsatility index (PI) will be measured using Doppler ultrasound during delivery (active labor or same day prior to cesarean) Uterine artery pulsatility index (PI) will be measured using Doppler ultrasound within 4 hours postpartum. The change in PI will be assesed as delta PI, both absolute as in percentage change of PI.
Change in uterine artery Systolic/Diastolic Ratio across peripartum period
Uterine artery systolic/diastolic ratio will be measured using Doppler ultrasound at three time points: before delivery (after 37 weeks), during delivery (active labor or same day prior to cesarean), and within 4 hours postpartum.
Correlating CEUS findings with uterine artery Doppler parameters within 4 hours postpartum
Correlation will be assessed between CEUS findings (presence of persisting spiral arteries detected using contrast enhanced ultrasound with Sonovue) and uterine artery Doppler parameters (Resistance Index \[RI\], Pulsatility Index \[PI\], and Systolic/Diastolic ratio). CEUS will follow the standardized imaging protocol for spiral artery visualization, and Doppler measurements will be obtained using standard obstetric ultrasound techniques.
Click on the lead sponsor to view all of their trials.
