School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
Department of Obstetrics and Gynaecology, Fondazione Monza e Brianza per il Bambino e la sua Mamma, Monza, Italy.
BMJ Open. 2021 Dec 6;11(12):e052510. doi: 10.1136/bmjopen-2021-052510.
The term placenta praevia defines a placenta that lies over the internal os, whereas the term low-lying placenta identifies a placenta that is partially implanted in the lower uterine segment with the inferior placental edge located at 1-20 mm from the internal cervical os (internal-os-distance). The most appropriate mode of birth in women with low-lying placenta is still controversial, with the majority of them undergoing caesarean section. The current project aims to evaluate the rate of vaginal birth and caesarean section in labour due to bleeding by offering a trial of labour to all women with an internal-os-distance >5 mm as assessed by transvaginal sonography in the late third trimester.
The MODEL-PLACENTA is a prospective, multicentre, 1:3 matched case-control study involving 17 Maternity Units across Lombardy and Emilia-Romagna regions, Italy. The study includes women with a placenta located in the lower uterine segment at the second trimester scan. Women with a normally located placenta will be enrolled as controls. A sample size of 30 women with an internal-os-distance >5 mm at the late third trimester scan is needed at each participating Unit. Since the incidence of low-lying placenta decreases from 2% in the second trimester to 0.4% at the end of pregnancy, 150 women should be recruited at each centre at the second trimester scan. A vaginal birth rate ≥60% in women with an internal-os-distance >5 mm will be considered appropriate to start routinely admitting to labour these women.
Ethical approval for the study was given by the Brianza Ethics Committee (No 3157, 2019). Written informed consent will be obtained from study participants. Results will be disseminated by publication in peer-reviewed journals and presentation in international conferences.
NCT04827433 (pre-results stage).
前置胎盘是指胎盘位于子宫内口上方，而低置胎盘是指胎盘部分位于子宫下段，胎盘下缘距宫颈内口 1-20mm（内口距离）。对于低置胎盘的产妇，最合适的分娩方式仍存在争议，大多数产妇行剖宫产。本研究旨在通过经阴道超声评估所有内口距离>5mm 的产妇经阴道分娩的可能性，并对其进行试产，评估晚期妊娠经阴道分娩和因出血行剖宫产的比例。
MODEL-PLACENTA 是一项前瞻性、多中心、1:3 病例对照研究，涉及意大利伦巴第和艾米利亚-罗马涅地区的 17 个产科单位。研究纳入在妊娠中期超声检查时胎盘位于子宫下段的产妇。正常位置胎盘的产妇作为对照组。每个参与单位在晚期妊娠超声检查时需要纳入 30 名内口距离>5mm 的产妇。由于低置胎盘的发生率从妊娠中期的 2%下降到妊娠末期的 0.4%，每个中心在妊娠中期超声检查时需要纳入 150 名产妇。如果内口距离>5mm 的产妇经阴道分娩率≥60%，则认为可以常规开始对这些产妇进行试产。
本研究已获得 Brianza 伦理委员会的批准（No 3157，2019）。将获得研究参与者的书面知情同意。研究结果将通过在同行评议期刊上发表文章和在国际会议上展示来传播。
NCT04827433（预注册阶段）。
