Preoperative and Intraoperative Sonographic Assessment of Lower Uterine Segment Thickness at Term in Women With Previous Cesarean Delivery - a Ultrasound Method Comparison Study

Study Overview
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Brief Summary
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This prospective, clinical, observational study compares preoperative and intraoperative sonographic assessment of lower uterine segment of women who underwent ≥ second cesarean section. It is the purpose of the study to assess transabdominal (linear/convex ultrasound probe) and transvaginal approach versus intraoperative sonographic assessment of lower uterine segment.

Detailed Description
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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 [https://www.destatis.de]. 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 [Cunningham et al., 2009]. 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? [AQUA-Institut] The information for the risk of uterine rupture remains insufficient based only on ultrasonography assessment [Varner et al., 2012]. The measurement technique for lower uterine segment (myometrial) thicknesses in the third trimester have been described by several authors. Using a combination of preoperative transvaginal and transabdominal (linear/convex probe) ultrasound, we compare with intraoperative sonographic assessment of lower uterine segment of women who underwent ≥ second cesarean section. The aim of the present study is to assess transabdominal (linear/convex ultrasound probe) and transvaginal approach versus intraoperative sonographic assessment of lower uterine segment. This will allow the investigators to draw conclusions regarding the best method to assessment of lower uterine segment (myometrial) thickness in the third trimester to predict successful trial of labor after cesarean delivery.

Official Title
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Präoperative Und Intraoperative Sonografische Beurteilung Des Unteren Uterinsegmentes im Rahmen Der Re-Sectio Caesarea - Eine Ultraschall- Methoden-Vergleichsstudie

Conditions
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Scar; Previous Cesarean Section

Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference between preoperative and intraoperative sonographic assessment of lower uterine segment I | Bland-Altman-Plot (mean versus difference) of Method A) Preoperative measurement of minimum myometrium-only thickness overlying the amniotic cavity at the level of the lower uterine segment scar - measured with transabdominal (linear ultrasound probe) and with transvaginal sonography (vaginal ultrasound probe) with the lowest value (thinnest area) being retained AND Method B) Intraoperative measurement of minimum myometrium-only thickness overlying the amniotic cavity at the level of the lower uterine segment scar - measured with intraoperative sonography after preparation of lower uterine segment (linear ultrasound probe) | intraoperative - just bevore the uterotomy | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference between preoperative and intraoperative sonographic assessment of lower uterine segment IIA | Bland-Altman-Plot (mean versus difference) of Method A) Preoperative measurement of minimum myometrium-only thickness overlying the amniotic cavity at the level of the lower uterine segment scar - measured with transabdominal (linear ultrasound probe) AND Method B) Intraoperative measurement of minimum myometrium-only thickness overlying the amniotic cavity at the level of the lower uterine segment scar - measured with intraoperative sonography after preparation of lower uterine segment (linear ultrasound probe) | intraoperative - just bevore the uterotomy | 
| Difference between preoperative and intraoperative sonographic assessment of lower uterine segment IIB | Bland-Altman-Plot (mean versus difference) of Method A) Preoperative measurement of minimum myometrium-only thickness overlying the amniotic cavity at the level of the lower uterine segment scar - measured with transabdominal (convex ultrasound probe) AND Method B) Intraoperative measurement of minimum myometrium-only thickness overlying the amniotic cavity at the level of the lower uterine segment scar - measured with intraoperative sonography after preparation of lower uterine segment (linear ultrasound probe) | intraoperative - just bevore the uterotomy | 
| Difference between preoperative and intraoperative sonographic assessment of lower uterine segment IIC | Bland-Altman-Plot (mean versus difference) of Method A) Preoperative measurement of minimum myometrium-only thickness overlying the amniotic cavity at the level of the lower uterine segment scar - measured with transvaginal sonography (vaginal ultrasound probe) AND Method B) Intraoperative measurement of minimum myometrium-only thickness overlying the amniotic cavity at the level of the lower uterine segment scar - measured with intraoperative sonography after preparation of lower uterine segment (linear ultrasound probe) | intraoperative - just bevore the uterotomy | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Caesarean section, lower uterine segment, sonography