Functions of the placenta

The placenta is an ephemeral materno-fetal organ with chorionic (fetal) villi bathed in maternal blood spaces, which allows restricted transfer of metabolites and drugs across specialized transfer areas. The placenta develops respiratory, nutritive and excretory functions while the fetal organs mature, and is also an important endocrine organ.     

Functions of the placenta

The placenta is an organ that connects a developing fetus to the uterine wall for the exchange of nutrients, antibodies and hormones between mother and fetus. It is required for the removal of waste products. The development of the placenta is essential for the removal of waste products. The development of the placenta is essential for fetal growth, development and the maintenance of a healthy pregnancy and it is an important endocrine organ.     

Functions of the placenta

The placenta is an ephemeral materno-fetal organ with chorionic (fetal) villi bathed in maternal blood spaces, which allows restricted transfer of metabolites and drugs across specialized transfer areas. The placenta develops respiratory, nutritive and excretory functions while the fetal organs mature, and is also an important endocrine organ.     

前置胎盘、胎盘粘连及胎盘植入与人工流产的关系研究

目的：研究前置胎盘、胎盘粘连及胎盘植入与人工流产的相关性。方法对入我院进行分娩的3280例孕妇资料进行分析,选择其中342例发生胎盘异常孕妇进行研究,包括未经人工流产和人工流产的孕妇前置胎盘、胎盘粘连及胎盘植入的发生率;人工流产的次数与前置胎盘、胎盘粘连及胎盘植入的关系以及围产期感染相关因素的研究。结果未经人工流产孕妇胎盘总的异常率为3.7%,人工流产孕妇胎盘总的异常率为14.3%,两组胎盘异常总发生率比较显著差异（P＜0.05）;流产次数越多,胎盘异常发生率随着次数增高而增高;围产期感染与产前贫血、宫腔感染和产妇营养不良关系密切（P＜0.05）。结论前置胎盘、胎盘粘连及胎盘植入与人工流产的关系密切,多次人工流产易导致胎盘异常情况的发生,又易由于胎盘异常导致产后出血,育龄女性应尽量避免人工流产。     

胎盘生长因子的病理学作用

肿瘤的血管生成是肿瘤发生、发展、转移过程中的重要环节,受多种因子调节.胎盘生长因子是血管内皮生长因子家族中的一员,氨基酸序列和VEGF-A有高度的同源性,以VEGFR-1为受体.胎盘生长因子(placenta srowth factor,PLGF)在生理条件下,在成年人、成熟组织中表达弱,但在病理条件下,如缺氧、外伤、肿瘤等,是一种重要的病理性血管生成因子,在病理性妊娠、特别是多种肿瘤组织中有高表达,而且和肿瘤的病理程度相关,对其研究具有重要的临床价值.     

Sir William Turner and his studies on the mammalian placenta

William Turner was appointed Professor of Anatomy at the University of Edinburgh in 1867, and from 1903 until his death in 1916, he was Principal and Vice-Chancellor. He was an outstanding teacher and many of those he taught went on to occupy chairs of anatomy. He published widely on anatomical subjects and one of his interests was comparative anatomy and physiology of the placenta. This paper takes a brief look at Turner's studies on the anatomical structure of the placenta, its comparative anatomy, his thoughts about its physiology and its place in the evolutionary process. At the time, these lectures constituted an anatomical and physiological classic. At the time Turner prepared his lectures, which were delivered in 1875 and 1876, little was known about the gestatory process in marsupials or monotremes. These mammals have a very brief period of intrauterine gestation and placentation and mention is made of studies that have been done in recent times on this subject.     

子宫动脉栓塞术用于胎盘植入性疾病

胎盘植入性疾病(PAS)属于产科危急重症,可致围产期难治性大出血、失血性休克、弥漫性血管内凝血,剖宫产手术出血量、输血量、子宫切除率及死亡率均较高。子宫动脉栓塞术(UAE)用于治疗PAS可有效栓塞子宫动脉主干及其分支,减少手术出血量及输血量,降低子宫切除率。本文对UAE用于PAS进展进行综述。     

超声检查新技术诊断胎盘植入性疾病研究进展

胎盘植入性疾病（PAS）早期临床表现隐匿,诊断困难,但产后并发症严重,甚至危及母亲和新生儿生命。以常规超声为基础,联合各种超声检查新技术,可提高PAS早期诊断准确率,有助于临床医师制订合理治疗方案以改善预后。本文对超声检查新技术诊断PAS研究进展进行综述。     

Extracorporeal fetal support: A new animal model with preservation of the placenta

Background

Previous models of support for premature sheep fetuses have consisted of cesarean delivery followed by catheterization of umbilical or central vessels and support with extracorporeal membrane oxygenation (ECMO). The limitations of these models have been insufficient blood flow, significant fetal edema, and hemorrhage related to anticoagulation.

Methods

We performed a gravid hysterectomy on 13 ewes between 135 and 145 days gestational age. The uterine vessels were cannulated bilaterally and circulatory support was provided via ECMO. Successful transition was defined as maintenance of fetal heart rate for 30 minutes after establishing full extracorporeal support. Circuit flow was titrated to maintain mixed venous oxygen saturation (SvO₂) of 70–75%.

Results

Seven experiments were successfully transitioned to ECMO, with an average survival time of 2 hours 9 minutes. The longest recorded time from cannulation to death was 6 hours 14 minutes. By delivering a circuit flow of up to 2120 ml/min, all but one of the transitioned uteri were maintained within the desired SvO₂ range.

Conclusion

We report a novel animal model of fetal ECMO support that preserves the placenta, mitigates the effects of heparin, and allows for increased circuit flow compared to prior techniques. This approach may provide insight into a technique for future studies of fetal physiology.     

The human placenta: a complementary method for microsurgical training

Summary Alternative methods to living animals are actually often necessary in microsurgical training. The human placenta presents many advantages, such as easy availability at no cost and the great number of suitable vessels on its fetal surface. On the basis of their experience, the authors suggest that the human placenta may be a satisfactory alternative when living animals are not available.     

Anaesthesia for abnormally invasive placenta: a single-institution case series

BackgroundAbnormally invasive placenta describes a spectrum of disorders resulting in pathological placental implantation. It is associated with the potential for severe maternal haemorrhage and poor fetal outcome. Increasing numbers of women are at risk owing to the rising incidence of uterine surgery and increasing maternal age. We report data over a five-year period describing anaesthetic management of cases of abnormally invasive placenta in a UK tertiary-referral maternity unit and assess how management has developed.MethodsSurgically confirmed cases of abnormally invasive placenta were identified from January 2011 to January 2016. Cases were identified using standard ICD-10 codes and by review of departmental records, with surgically-confirmed cases included following review of medical records.ResultsForty cases of abnormally invasive placenta were identified. Eighteen (40%) women had significant medical co-morbidity. All parturients were delivered by caesarean delivery. Caesarean hysterectomy occurred in 24 (60%) cases, delayed hysterectomy in two (5%) and the uterus was preserved in the remaining 14 (35%). Thirty-eight (95%) caesarean deliveries were commenced under neuraxial anaesthesia with 17 (45%) converted to general anaesthesia intraoperatively. Interventional radiology was undertaken in 23 (58%) cases. Median [range] estimated blood loss was 1700 mL [500–12000 mL]. Intraoperative transfusion of packed red cells occurred in 14 (35%) cases. Intraoperative cell salvage was used in 26 (65%) cases. Four (10%) women were admitted to critical care postoperatively. There were no maternal deaths.ConclusionOur data illustrate the burden on healthcare resources associated with management of abnormally invasive placenta, underlining the continued need for centralised services for treatment of these complex cases. An integrated multidisciplinary approach to case planning, case management and service provision is key to a successful outcome in these cases.     

The anaesthetic management of Caesarean section for placenta praevia: a questionnaire survey

The purpose of this study was to determine current UK anaesthetic practice regarding the use of regional anaesthesia in the management of patients with placenta praevia presenting for Caesarean section. We asked the members of the Obstetric Anaesthetists Association to complete a postal questionnaire in which a range of clinical situations involving varying degrees of placenta praevia were presented. In each case respondents were asked whether they would be willing to use regional anaesthesia. A wide variety of clinical practice was demonstrated. Anaesthetists with two or more obstetric sessions were more willing to use regional anaesthesia for Caesarean section in the presence of placenta praevia in both elective and emergency situations associated with haemorrhage.     

Congenital hepatic mesenchymal hamartoma associated with mesenchymal stem villous hyperplasia of the placenta: case report

A newborn with an unusual association of hepatic mesenchymal hamartoma and mesenchymal stem villous hyperplasia of the placenta is presented. At birth, the large hepatic mass caused severe respiratory distress necessitating early surgical intervention. This report on the association of hepatic mesenchymal hamartoma and mesenchymal stem villous hyperplasia of the placenta strongly suggests a common pathogenetic origin of the 2 lesions.     

Fifty years of work on the artificial placenta: milestones in the history of extracorporeal support of the premature newborn

The concept of an artificial placenta has been pursued in experimental research since the early 1960s. The principle has yet to be successfully implemented in neonatal care despite the constant evolution in extracorporeal life support technology and advancements in neonatal intensive care in general. For more than three decades, the physical dimensions of the required equipment necessitated pump‐driven circuits; however, recent advances in oxygenator technology have allowed exploration of the simpler and physiologically preferable concept of pumpless arteriovenous oxygenation. We expect that further miniaturization of the extracorporeal circuit will allow the implementation of the concept into clinical application as an assist device. To this end, NeonatOx ( Fig. 1 ), a custom‐made miniaturized oxygenator with a filling volume of 20 mL, designed by our own group, has been successfully implemented with a preterm lamb model of less than 2000 g body weight as an assist device. We provide an overview of milestones in the history of extracorporeal membrane oxygenation of the preterm newborn juxtaposed against current and future technological advancements. Key limitations, which need to be addressed in order to make mechanical gas exchange a clinical treatment option of prematurity‐related lung failure, are also identified.

Figure 1 Open in figure viewer PowerPoint NeonatOx, a low‐volume extracorporeal assist device for preterm lung failure.     

Functions of the splenic remnant after subtotal splenectomy for treatment of severe splenic injuries

BACKGROUND: To evaluate the clinical and laboratory characteristics of patients submitted to subtotal splenectomy during the immediate and late postoperative period. METHODS: The study was conducted on 34 patients, 25 of whom were submitted to subtotal splenectomy (group I), and 9 to total splenectomy without preservation of splenic tissue (group II), and on 22 patients with intact spleens (group III, control). The immediate and late postoperative complications were investigated. Hematological examinations were performed during the late postoperative period (red cell count, hemoglobin, platelets, total and segmented leukocytes, lymphocytes, and Howell-Jolly bodies). Immunoglobulins (IgA, IgM, and IgG) and total T lymphocytes (TTL), active T lymphocytes (ATL), and B lymphocytes were also determined. Splenic scintigraphy with (99m)Tc colloidal sulfur was performed. RESULTS: Groups I and III did not presented abnormal blood bodies and their hematological and immunological pattern were normal. None of the groups showed leukocytosis or thrombocytosis. Howell-Jolly bodies were observed only in group II, which also showed reduced IgM levels. Scintigraphy showed filtering splenic tissue in group I. CONCLUSIONS: We conclude that subtotal splenectomy is a good surgical alternative for serious distal spleen lesion or when the main splenic pedicle is injured.     

The artificial placenta: Continued lung development during extracorporeal support in a preterm lamb model

Purpose

An artificial placenta (AP) utilizing extracorporeal life support (ECLS) could avoid the harm of mechanical ventilation (MV) while allowing the lungs to develop.

Effect of prophylactic placement of internal iliac artery balloon catheters on outcomes of women with placenta accreta: an impact study

We performed an impact study on the introduction of routine placement of internal iliac artery balloon catheters for the management of haemorrhage during caesarean section in women with placenta accreta. We identified 11 women, with prenatally diagnosed placenta accreta/increta/percreta before this change in practice, who acted as controls, and 30 women who had iliac artery balloons placed. The balloons were inflated in 27 cases. The median (IQR [range]) intra‐operative blood loss was 1100 (800–2600 [500–6000]) ml in controls, compared with 1000 (600–2513 [400–15000]) ml in women with iliac artery balloons (p = 0.64). Six (54%) controls received intra‐operative blood transfusion compared with 14 (47%) women with iliac artery balloons (p = 0.66). Caesarean hysterectomy was performed in 3 (27.3%) controls and 13 (43.3%) women with iliac artery balloons (p = 0.48). Balloon catheter insertion was associated with a shortened postoperative hospital stay, 6 (5–7 [4–12] days in controls vs. 5 (4–6 [3–10]) in the iliac artery balloon group (p = 0.033). General anaesthesia was used in six (54%) controls, but all women with iliac artery balloons. This study demonstrates that prophylactic balloon occlusion of the internal iliac arteries did not reduce intra‐operative haemorrhage or caesarean hysterectomy in women with placenta accreta undergoing caesarean section. In addition, it has a significant impact on the choice of anaesthetic technique.     

Gastrointestinal mucosal development and injury in premature lambs supported by the artificial placenta

Background

An Artificial Placenta (AP) utilizing extracorporeal life support (ECLS) could revolutionize care of extremely premature newborns, but its effects on gastrointestinal morphology and injury need investigation.