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The fetal membranes separate maternal tissue from fetal tissue at a basic mechanical level. The fetal membrane is composed of a thick cellular chorion covering a thin amnion composed of dense collagen fibrils. The amnion is in contact with the amniotic fluid and ensures structural integrity of the sac due to its mechanical strength.
As the fetal hypothalamus matures, the activation of the hypothalamic–pituitary–adrenal (HPA) axis initiates labor through two hormonal mechanisms. The end pathway of both mechanisms lead to contractions in the myometrium, a mechanical cause of placental separation, which is due to the sheer force and contractile and involutive changes that occur within the uterus, distorting the placentome.
The presence of a "T-sign" at the inter-twin membrane-placental junction is indicative of monochorionic-diamniotic twins (that is, the junction between the inter-twin membrane and the external rim forms a right angle), whereas dichorionic twins present with a "lambda (λ) sign" (that is, the chorion forms a wedge-shaped protrusion into the ...
Normally the maternal circulation and the fetal circulation are kept from direct contact with each other, with gas and nutrient exchange taking place across a membrane in the placenta made of two layers, the syncytiotrophoblast and the cytotrophoblast. Fetal-maternal haemorrhage occurs when this membrane ceases to function as a barrier and ...
The third membrane is the allantois, and the fourth is the chorion which surrounds the embryo after about a month and eventually fuses with the amnion. [ 6 ] Amniocentesis is a medical procedure where fluid from the sac is sampled during fetal development , between 15 and 20 weeks of pregnancy, to be used in prenatal diagnosis of chromosomal ...
Premature rupture of membranes [8] Prolonged rupture of membranes (>24 hours). [11] Thrombophilia [10] Polyhydramnios [8] Multiparity [10] Multiple pregnancy [10] Maternal age: pregnant women who are younger than 20 or older than 35 are at greater risk; Risk factors for placental abruption include disease, trauma, history, anatomy, and exposure ...
The placenta (pl.: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation.It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate maternal and fetal circulations, and is an important endocrine organ, producing hormones that regulate both maternal and fetal ...
The accurate diagnosis of circumvallate placenta during pregnancy can have significant implications in the recognition of patients who are at risk of complications. Although the ability of sonography to accurately diagnosis circumvallate placenta during pregnancy is quite limited, research studies continue to emerge at the possibility of doing so.