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Published in Bobby Krishnachetty, Abdul Syed, Harriet Scott, Applied Anatomy for the FRCA, 2020
Bobby Krishnachetty, Abdul Syed, Harriet Scott
All these vessels anastomose extensively which explains why ligation of the smaller vessels does not control uterine haemorrhage and that aortic clamping might be necessary. Maternal blood circulates freely within the intervillous space. The mean pressure at the arterial side is 70 mmHg, 10 mmHg in the intervillous space and less than 10 mmHg in the venous side of the maternal circulation.
Physiology of the Placenta
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The basic structural unit of the human placenta is the chorionic villus. The villi are vascular projections of fetal tissue surrounded by chorion, the outermost layers of fetal tissue. The chorion consists of two layers, the syncytiotrophoblast, which is in direct contact with maternal blood within the intervillous space, and the cytotrophoblast (Figure 73.1). Substances in maternal blood are carried into the intervillous space and pass through the two layers of trophoblast, fetal connective tissue and endothelium of fetal capillaries into fetal blood. During pregnancy, the placenta grows to provide an ever larger surface area for maternal–fetal exchange.
Anti-Phospholipid Antibodies and Fetal Loss-Proposed Mechanisms
Published in E. Nigel Harris, Thomas Exner, Graham R. V. Hughes, Ronald A. Asherson, Phospholipid-Binding Antibodies, 2020
Normal pregnancy relies upon the development of both utero-placental and feto-placental circulation and fetal compromise may therefore occur either because of factors on the maternal, fetal or both sides of the intervillous space.
CD42b Immunostaining as a Marker for Placental Fibrinoid in Normal Pregnancy and Complications*
Published in Fetal and Pediatric Pathology, 2021
The clinical significance and functions of various types of fibrinoid within the placenta are largely unknown, and the fibrin-type fibrinoid within the intervillous spaces was initially thought to represent the barrier from the fetal hemorrhage into the maternal circulation in erythtroblastosis fetalis, and this was supported by the presence of the nucleated red blood cells within the fibrinoid material (Kline hemorrhage) [20]. Subsequent studies support the view that the lining syncytiotrophoblasts of the villous tree depend on the maternal circulation and the damage of the syncytiotrophoblasts leads to intervillous thrombosis [21]. Maternal circulation within the placenta is sinusoidal, and the blood flow within the intervillous spaces is affected by the villous trees with complexity but it is clearly different from that of vascular luminal flow [22]. The intervillous spaces connect the uterine spiral arteries/arterioles to the uterine veins/venules with an order of magnitude of more capacities to facilitate the oxygen and nutrient transfers to the fetus [23]. Formation of fibrinoids at various anatomic locations within the placenta is likely the result of different mechanisms involving mechanical blood flow changes and biochemical responses of trophoblasts to molecular signals in different disease states [2]. Understanding the nature of the fibrinoids provides helpful insights in clinical diagnosis of various placental lesions in normal pregnancy and its related complications.
Increased levels of serum serglycin and agrin is associated with adverse perinatal outcome in early onset preeclampsia
Published in Fetal and Pediatric Pathology, 2019
Basak Gumus Guler, Sibel Ozler
Preeclampsia is associated with increased risk of adverse pregnancy outcomes, such as fetal growth restriction (FGR), preterm delivery, and intrauterine fetal death (IUFD) [3]. It may cause cerebrovascular complications such as intracranial bleeding, eclampsia, posterior reversible encephalopathy syndrome, pulmonary edema, acute renal failure, and maternal death [4, 5]. Maternal complications, namely chronic hypertension, cardiovascular disease, metabolic disease, and renal disease may also be observed in late-term [6–8]. The factors responsible for disease pathogenesis and/or predictive of adverse fetal and maternal outcomes have not been clearly defined. The improvement in impaired clinical and laboratory parameters after labor suggests the placenta has a major role in disease pathogenesis. Human extravillous trophoblasts invade the maternal decidua and reconstruct maternal spiral arterioles during early placentation. As a result, this allows the passage of maternal blood into intervillous space to support continuous placental function. The blood in the intervillous space supplies the fetus with oxygen and nutrients at the villous trophoblastic interface [9]. The extravillous trophoblasts are the main placental structure interacting with spiral arterioles in the uterine decidua [10].
Placenta structural changes in heavy smoking mothers: a stereological aspect
Published in Current Medical Research and Opinion, 2018
Zahra Heidari, Hamidreza Mahmoudzadeh-Sagheb, Nadia Sheibak
An increase in the volume of intervillous space in our samples might be a mechanism to collate against reduced oxygen diffusion across the placenta in the smoker group by increasing surface area for sufficient gas transfer3,4,18,21. In addition, it has been suggested that an increase in intervillous spaces could be correlated to the increment of placenta volume13. On the other hand, we found that the Vt of blood vessels in the placentas of heavy smoking women was decreased compared to the control group; however, it was not statistically significant. In addition, the Vd of blood vessels significantly decreased in the heavy smoker group compared to the control group. It could be another reason for the reduction in blood flow to the placenta in smokers and the necessity of compensatory mechanisms22.