Prediction of Uterine Atony After Vaginal Delivery by Elastography

Prediction of Uterine Atony After Vaginal Delivery by Shear Wave Elastography: a Feasibility Study

Prospective study evaluating the feasibility of shear-wave elastography of the uterus during the third stage of labour and following placental delivery. The investigators hypothesize that the stiffness of the myometrium can be measured by using shear-wave technology. This study involves 30 patients with a healthy pregnancy and spontaneous vaginal delivery. One co-investigator will carry out measurements at the uterine fundus, at three different time points: after fetal delivery, after placental delivery and 30 minutes after placental delivery.

Inclusion Criteria:

• singleton pregnancy
• cephalic presentation
• maternal age > 18 years old
• nulliparous
• healthy uncomplicated pregnancy
• gestational age between 37-42 weeks of gestation
• spontaneous labour and delivery
• uncomplicated progression of labour (cervical dilatation at >1 cm/h)
• administration of less than 3 units of oxytocin during the second stage of labour
• patient having read, accepted and signed the consent form

Exclusion Criteria:

• antepartum hemorrhage in the present pregnancy
• protracted second stage of labour (more than two hours from full dilatation to delivery)
• more than 30 minutes of active pushing
• BMI > 35 kg/m2
• distance from skin to uterus > 8 cm
• age > 35 years old
• instrumental deliveries
• bleeding disorders
• polyhydramnios
• diabetes
• pre-eclampsia
• high blood pressure
• use of anticoagulant medications
• clinical chorioamnionitis
• placental abnormality (low-lying or abruption)
• fetal macrosomia
• uterine fibroids
• uterine anomalies
• previous uterine scar
• multiple pregnancy
• placental retention
• inability to follow procedures or insufficient knowledge of project language
• inability to give consent
• refusal to participate