Before the fertilized egg reaches the uterus, the uterine mucosa becomes thinner and more vascularized and is called the decidual mucosa, and the membrane that covers the egg is called capsule decidual. The portion that intervenes between the uterus and the egg that will become the maternal part of the placenta and is called decidedly basic. The moment of implantation of the egg in the uterine mucosa also presents its bleeding in small quantities, this taking place in the first trimester of pregnancy.
The corion (external embryo shell) has two layers: an external trophoblast and an internal mesoblast.
The trophoblast grows and will form the chorionic vein that invades the uterine decidua and will absorb the nutrients needed to grow the embryo.
The chorionic villi will grow in size and branch out, while the mesoderm that already has branches from the umbilical vessels will grow inside them, so they are vascularized. The branches from the umbilical vessels will vascularize the villa.
The placenta connects the fetus to the walls of the uterus and is the organ through which the functions of breathing, excretion and nutrition of the fetus are performed. The fetal portion of the placenta consists of chorion villas and the maternal part of the basal decidua.
Chorionic separation from the endometrial area may lead to the appearance of hematomas in the vicinity or initial portion of the implant.
There are several types of hematomas, including subcortical hematomas - in which only the edge of the placenta is separated; retroplacental hematomas - where the bleeding occurs behind the placenta and subamniotic or preplacental hematomas, where the bleeding occurs before the placenta and are separated by the umbilical cord.
Subcorionic hematomas are the most common, the subamniotic ones rarely, and the retroplacental ones are mostly found in the third trimester of pregnancy.
Causes of decidual hematoma
Obstetric trauma is one of the causes of placenta interruption, with 1-2% of cases due to trauma. A very small trauma can cause a mild interruption of the placenta, which can develop into a severe interruption in less than 24 hours.
Such a traumatic accident of the abdomen may be the cause of the onset of the decidual hematoma. In the case of a minor trauma, a small hematoma will appear, which will push the tissue of the placenta, but the blood flow between the uterus and the placenta will not change, so it remains normal, so in this case, there are no symptoms.
The hematoma will form a curve with a black blood shell at the place of the maternal placenta.
If the bleeding is severe, the muscle of the uterus that is already in tension will not be able to contract to stop the bleeding. The hematoma will increase and cause a partial or total separation of the placental tissue from the walls of the uterus. The blood will penetrate beneath the amniotic membrane and will spread through the fibers of the muscle, making the patient feel increased tension and pain.
Damage to the uterine wall and retroplacial hematoma will increase thromboplastin secretion in the maternal circulation, which will lead to intravascular coagulation.
The safety of the fetus depends on the area of separation, a simple separation has no symptoms and does not affect the fetus. Death caused by hypoxia may occur if some or all of the placental tissue will separate. In this case, time is a huge factor in abnormal blood coagulation, dialysis dysfunction and fetal death. The longer the time between the interruption of the placenta and the birth, the more complications may occur.
Trauma to the abdomen can cause some complications, such as ruptured uterus, complete or incomplete. In the incomplete one, the hematoma can be formed so that it cannot be recognized and can cause severe complications and death.
In case of a late complication of CVS (chorionic villi biopsy - prenatal test performed in the first stages of pregnancy to detect the birth defects of the fetus), a retroplacental hematoma will be formed immediately at the place where the sample was taken, by a bleeding from a at the other end of the cervix. The retroplacental hematoma, as well as the bleeding, will continue throughout the pregnancy until the Caesarean birth at 31 weeks after amenorrhea.
Risk factors, symptoms and diagnosis
Most patients with small subchorionic hematomas have no symptoms, manifestations in the case of large hematomas are: premature birth, painful vaginal bleeding, abdominal pain, risk of abortion in the first or second trimester.
In the case of retroplacial hematomas of the third semester of pregnancy are: painful vaginal bleeding, the existence of uterine tension, fetal distress and abnormal blood coagulation.
Of the fetus:
Bleeding along the basal plate of the placenta, separating it from the wall of the uterus will lead to a first rupture of the placenta but also of the spiral arteries. These have the following causes: hypertension (smoking), smoking, ethanol abuse or drugs. The death of the fetus represents the overall result of placental infarction due to rupture of the arteries or extrinsic compression caused by the retroplacental hematoma when a large portion of placental tissue becomes involved.
Retroplacental hematoma may remain asymptomatic or present as placental rupture characterized by painful vaginal bleeding, blood coagulation disorders, acute kidney disease resulting from necrosis at the cortical level and fetal distress.
Vaginal bleeding occurs due to large retroplacental hematomas once the peripheral margins of the placenta are interrupted and the fetal membranes are practically peeled. Death of the fetus is not common with hemorrhage because the placenta is not sufficiently compressed for this to occur.
At ultrasound, the retroplacental hematoma can mimic a thin placenta.
The results of the studies indicate that a large number of patients with subcorionic hematomas have been identified between weeks 10-20 of pregnancy, in 60% of cases the chances are not favorable, but these depend on the size and location of intrauterine hematomas.
Tags Healthy pregnancy