This prospective, clinical, observational trial compares the measured value with quantitative ultrasonic (preoperatively) Elastic modulus E (kPA) with the measured value with quantitative ultrasonic Elastic modulus E (kPA) in vitro (postoperatively) and with the experimental measurement done in vitro (postoperatively) of lower uterine segment of women who underwent second cesarean section.

In 1991, 126.297 (15.3%) women delivered by caesarean section in Germany. Since then, the rate of caesarean section increased steadily over the next 20 years, reaching up to 32.2% in 2011. The absolute risk of uterine rupture in vaginal birth after Caesarean section is 1 in 100 deliveries. The risk of perinatal death or the outcome of extremely neurological impairment is 1 in 1000 deliveries.

Statistically more than 300 pregnant women with a prior caesarean delivery visit daily ultrasound departments of german hospitals to investigate the C-section scar before delivery. They have one important question: Is it possible to predict successful trial of labor after cesarean delivery? The information for the risk of uterine rupture remains insufficient based only on ultrasonography assessment.

What are the possibilities of additional parameters to examine the stability of uterine scar tissue? Currently, there is no defined cut-off value of scar thickness for the prediction of uterine rupture. It remains questionable whether the thickness of the lower uterine segment is the determinant factor for the stability of the scar and the probability of rupture. However, another important factor is the functional elasticity or the structure of the connective tissue. It has not been further investigated until now (both quantitatively and qualitatively).

Objective of this project: Multimodalities of assessments, including ultrasonography and elastography, validate the accuracy of uterine scar stability in women with previous history of Caesarean section in vitro and in vivo.

Inclusion Criteria:

• pregnancy after previous cesarean section
• pregnancy between 37 0/7 and 42 0/7 weeks of gestation
• primary or secondary indication for cesarean section
• ability to give informed consent in german or english

Exclusion Criteria:

• emergency caesarean section
• <18 years old

Women with pregnancies after previous cesarean section who referre to the tertiary referral care center.

Pregnant women have been scheduled for a consecutive Caesarean section.