1 INTRODUCTION

The prenatal diagnosis of placental anomalies was one of the first use of ultrasound imaging in obstetrics from the end of the 1960s.^{1, 2} Conditions such as placenta praevia and hydatidiform mole had been known for centuries to be associated with a high maternal morbidity and mortality, when undiagnosed before labour for placenta praevia or when presenting with severe anaemia and eclampsia for a hydatidiform mole. Previous attempts at imaging the placenta in utero included soft tissue radiography with radioactive isotopes injected into the maternal circulation or the amniotic cavity and pelvic angiography using radio-opaque dyes injected into the femoral artery.

Ultrasound imaging rapidly proved more practical and safer than radiology techniques as it did not expose both mother and fetus to radiation. Rapid improvements in ultrasound resolution over the following decade made it possible to diagnose major fetal anomalies such as spina bifida,³ and a decade later, with the development of colour Doppler imaging, it became possible to accurately identification of small fetal vessels such as vasa praevia.⁴

Placenta praevia was originally defined using transabdominal sonography (TAS) as a placenta developing within the lower uterine segment and graded according to the relationship between the lowest placental edge and the internal cervical os.⁵ The use of high-resolution transvaginal ultrasound (TVS) has revolutionised the diagnosis and follow-up of placenta praevia by allowing accurate measurements of the distance between the presenting placental edge or vasa praevia and the internal os.^{6, 7} TVS has proven safe in patients suspected of having a placenta praevia on transabdominal ultrasound⁶ and the majority of pregnant patients in the UK who have TVS reported finding the experience acceptable.⁷

Overall, ultrasound imaging has changed the management and outcome of patients presenting with fetal congenital defects, abnormal fetal growth, multiple pregnancies and maternal obstetric disorders such as pre-eclampsia and gestational diabetes, and has led to the development of the subspeciality in materno-fetal medicine (MFM). Similarly, sonographers have become specialised in obstetric scanning. However, during this process, detailed ultrasound examination of the placenta and the umbilical cord has been left behind and is only superficially included in obstetric ultrasound training programmes.⁸ Furthermore, hyper-specialisation in fetal medicine scanning has limited the exposure of both MFM and sonographer trainees to the use of TVS, which is mainly used in gynaecology and in the evaluation of patients with early pregnancy complications in specialised gynaecology clinics and early pregnancy units. In the present commentary, we address these issues and the need for the examination of the placenta and umbilical cord to be included in national training programmes on obstetric ultrasound imaging.

中文翻译：

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产前保健中的胎盘和脐带：未被发现、被忽视和被误解

 1 引言

胎盘异常的产前诊断是 1960 年代末超声成像在产科中首次使用的一种^。几个世纪以来，人们一直知道前置胎盘和葡萄胎等疾病与高孕产妇发病率和死亡率有关，当前置胎盘在分娩前未诊断或葡萄胎出现严重贫血和子痫时。以前尝试对子宫内胎盘进行成像的尝试包括将放射性同位素注射到母体循环或羊膜腔中的软组织 X 线照相，以及使用注射到股动脉中的不透射线染料进行盆腔血管造影。

超声成像很快被证明比放射学技术更实用、更安全，因为它不会使母亲和胎儿都受到辐射。在接下来的十年中，超声分辨率的快速提高使诊断脊柱裂等主要胎儿异常成为可能，³ 十年后，随着彩色多普勒成像的发展，可以准确识别小胎儿血管，例如前血管。⁴

前置胎盘最初使用经腹超声检查 （TAS） 定义为胎盘在子宫下段内发育，并根据胎盘最低边缘与宫颈内口之间的关系进行分级。⁵ 高分辨率经阴道超声 （TVS） 的使用彻底改变了前置胎盘的诊断和随访，因为它可以准确测量前置胎盘边缘或前置血管与口腔内口之间的距离。^6、7TVS 已被证明对经腹超声怀疑有前置胎盘的患者是安全的⁶，大多数接受 TVS 的英国孕妇报告认为这种体验是可以接受的。⁷

总体而言，超声成像改变了胎儿先天性缺陷、胎儿生长异常、多胎妊娠和孕产妇产科疾病（如先兆子痫和妊娠糖尿病）患者的管理和结果，并导致了母胎医学 （MFM） 亚专科的发展。同样，超声医师也开始专门从事产科扫描。然而，在此过程中，胎盘和脐带的详细超声检查已被遗忘，仅表面包含在产科超声培训计划中。⁸ 此外，胎儿医学扫描的高度专业化限制了 MFM 和超声医师实习生对 TVS 使用的接触，TVS 主要用于妇科以及在妇科专科诊所和早期妊娠病房评估早期妊娠并发症患者。在本评论中，我们讨论了这些问题以及将胎盘和脐带检查纳入国家产科超声成像培训计划的必要性。