Sail placenta

Introduction Sail-shaped placenta: In 1993, Fries et al. pointed out that single chorionic vaginal pregnancy combined with sail-shaped placenta had more transfusion than non-combined patients. They believed that the membranous umbilical cord was susceptible to pressure, and the amount of blood flow through the umbilical vein to a twin was reduced. More blood will flow to the other fetus through the placental vascular anastomosis, causing excessive amniotic fluid, which in turn can force the umbilical vein to cause a vicious circle. The authors pointed out that puncture a large amount of amniotic fluid can not only relieve symptoms but also treat it as a direct cause. The sail-shaped placenta belongs to the pathogenesis of neonatal hemorrhagic anemia.

Cause

(1) Causes of the disease

Prenatal bleeding

Mainly through the placenta blood loss, including fetal-placental bleeding, fetal-female blood transfusion and inter-fetal transfusion. Because of the concealment of bleeding, the amount of bleeding is not equal, the bleeding rate can be urgent and slow, so the clinical manifestations are different.

(1) Fetal-placental hemorrhage: refers to fetal bleeding to the placenta and causes neonatal anemia, which can cause hemorrhage after placental parenchyma or hemorrhage, resulting in the following two conditions:

1 Umbilical cord around the neck: When the umbilical cord around the neck, because the umbilical vein wall is thin, the pressure of the contracted umbilical cord first blocks the umbilical vein, and then the umbilical artery, so the fetus can not get the placental blood from the umbilical vein, and the umbilical artery continues to Fetal blood flows back to the placenta. If the fetus loses blood, it can lose 20% of blood volume.

2 After cesarean section: If the position of the baby is higher than the placenta before the umbilical cord is ligated, the blood flowing through the umbilical artery continues to flow to the placenta, and due to the hydrostatic pressure, the blood continues to flow back from the umbilical vein to the fetus. The blood volume of uterine birth is lower than that of vaginal delivery.

(2) Fetal-mother transfusion:

1 There is a pressure difference between the umbilical artery and the villus gap: there is a pressure difference between the umbilical artery and the villus, and the fetal water and metabolites can reach the mother. Therefore, the fetal blood can follow this route, especially when the villi are damaged, the blood can directly enter the maternal blood circulation. Some people examined the placenta in each stage of pregnancy and found that there are many small gaps in the placental barrier, which is secondary to the vascular death and villus infarction.

2 transabdominal amniocentesis: transabdominal amniocentesis has been widely used to treat neonatal hemolytic disease and perinatal genetic metabolic disease diagnosis, puncture needle can damage the placenta caused by bleeding. It has been reported that 10.8% fetal-maternal transfusion occurs after diagnostic amniocentesis.

3 other injuries: external reversal, intravenous oxytocin, maternal pregnancy-induced hypertension syndrome.

4 placental chorioangioma, villus cancer, etc.: fetal red blood cells can enter the blood circulation through the placenta at 4-8 weeks of gestation, or at the time of labor.

(3) Fetofetal transfutsion: twin blood transfusion is a complication of monochorionic twin pregnancy, with high perinatal morbidity and mortality. Herlitz first reported in 1941, its clinical manifestations More understanding has been made, but the pathogenesis is still unclear. In recent years, there has been some progress in the study of etiology. Therefore, there have been breakthroughs in treatment and increased survival rates.

An important condition for twin-transfusion is that there is a common fetal vascular bed between the two placenta. According to the study of placental vascular injection of milk, almost all of the vascular anastomoses exist in the single chorionic twin, with inter-arterial, inter-venous, and intercapillary The anastomosis, but mostly occurs in the movement, venous traffic type, which was proposed by Schatz in 1882, called the "third cycle", the blood supply from the arterial blood to the placental villi, from the venous return to the recipient, the incidence of the disease The mechanism has been challenged by the following new concepts:

1 Difference in serum protein concentration between twins: In 1963, Kloosterman proposed that blood donors circulate through the vascular anastomosis chronically to the recipient's circulation, because the protein can not pass through the placenta, the hypoproteinemia of the donor's circulation, the colloid osmotic pressure is low, and the water is returned to the mother. in vivo. Children with dehydration and growth are backward; while those with high proteinemia have high colloid osmotic pressure, and absorb a lot of water from the mother. The children grow faster, the amniotic fluid is too much, and the system can cause edema.

2 Differences in atrial natriuretic peptide levels between twins: In 1989, Nageotte found that the atrial natriuretic peptide level of the recipients was higher than that of the donors. The release of atrial natriuretic peptide was caused by the increase of blood volume, and it also promoted the increase of fetal urine production, resulting in amniotic fluid. Too much, Wieacker agreed with this conclusion in 1992, pointing out that the increase in amniotic fluid is due to the inhibition of vasopressin release.

3 sail placenta: In 1993, Fries et al pointed out that single chorionic vaginal pregnancy combined with snail-shaped placenta had more transfusion than non-combination. They believed that the membranous umbilical cord was easily compressed, and the amount of blood flow through the umbilical vein to a twin was reduced. More blood will flow through the placenta vascular anastomosis to another fetus, causing excessive amniotic fluid, which in turn can force the umbilical vein to cause a vicious circle. The authors pointed out that puncture and extraction of a large amount of amniotic fluid can not only relieve symptoms, but also directly Etiology treatment.

The difference in the function of the placenta between the twins: In 1992, Saunders et al proposed that the cause of twin-transfusion was the uterine placental insufficiency of the donor, the resistance around the placental circulation increased, and the blood was shunted to the recipient by vascular anastomosis. In 1993, Vetter proposed a small The response to fetal placental dysfunction and growth disorders is to release growth stimuli, but it is unable to respond to this stimuli due to incomplete placental dysfunction; while the other fetus has normal placental function, which stimulates the flow through vascular anastomosis. Promote growth after stimulation, a process known as the "growth factor sequence." Mostly caused by obstetric accidents during delivery, placenta and umbilical cord deformity. Blood loss after birth is more common in the umbilicus, gastrointestinal tract and internal hemorrhage. In recent years, blood loss has also increased due to hospital-based diagnostic blood sampling.

2. Blood loss at birth

Mostly caused by obstetric accidents during delivery, placenta and umbilical cord deformity.

(1) Abnormal placenta: severe blood loss often occurs in the placenta previa, early placenta stripping or cesarean section, which causes miscarriage of the placenta and causes blood loss. Placental malformation is more common with multi-leaf placenta, and each leaf emits a fragile vein branch to the placenta. The blood vessel is prone to bleeding.

(2) Umbilical cord abnormality: normal umbilical cord may suddenly bleed due to excessive involvement, umbilical cord malformation such as umbilical cord hemangioma, vagus blood vessel, etc., the latter is one or more blood vessels before the umbilical cord reaches its implantation site, and its blood vessel wall is thin. The lack of protection of umbilical cord-like tissue is extremely easy to rupture; the umbilical cord is placed in the placenta and the blood vessels are also passed between the amnion and the chorion without protection. The incidence of bleeding is 1% to 2%.

3. Blood loss after birth

Blood loss after birth is more common in the umbilicus, gastrointestinal tract and internal hemorrhage. In recent years, blood loss has also increased due to hospital-based diagnostic blood sampling.

(1) Loss of blood in the umbilicus: the cause can be due to:

1 When the umbilical cord is ligated, the umbilical cord is not tightly tied or the umbilical cord stump vessel is opened again and bleeding.

2 exchange blood through the umbilical vein cannula, exchange for low hemoglobin blood with excessive maintenance fluid.

3 Diagnostic umbilical vein blood was taken several times.

(2) Intestinal blood loss: caused by neonatal hemorrhagic disease, congenital intestinal malformation or necrotic enterocolitis.

(3) Internal bleeding: caused by birth injury, anemia often occurs 24 to 72 hours after birth, and more often accompanied by jaundice, there are several cases:

1 huge head hematoma or decidual subarachnoid hemorrhage.

2 intracranial hemorrhage: such as subdural and subarachnoid hemorrhage. A large amount of bleeding can cause anemia, cerebral ventricle in premature infants caused by asphyxia and hypoxia, and the amount of bleeding can reach 10% to 15% of children with blood volume.

3 liver and spleen rupture.

4 adrenal hemorrhage.

(two) pathogenesis

Neonatal blood loss can be caused by abnormal placenta separation (placental abruption), placenta previa, umbilical cord tear caused by birth injury, umbilical cord in the placenta with sail-like attachment tearing blood vessels, and cut into placenta previa during cesarean section. If the umbilical cord is tightly wrapped around the fetal neck or body during childbirth, arterial blood can be pumped from the fetus into the placenta, and the umbilical cord is blocked, preventing blood from flowing back into the baby through the umbilical vein; clamping the umbilical cord immediately during childbirth may cause severe acute concealment. Sexual blood loss (enter the placenta).

Fetal-mother bleeding in the uterus can cause recessive blood loss of varying degrees of severity. This bleeding may be acute or prolonged, or it may be chronic and recurrent. If the fetus has a compensation for bleeding, its hematocrit will decline for a while (because the blood volume expands again). Acute perinatal bleeding can cause fetal or neonatal shock, and the decline in hematocrit takes several hours. Positive Kleihauer test of maternal blood can confirm fetal bleeding; when fetal red blood cells enter the mother blood circulation, the acid-eluting characteristics can be determined by blood smears.

Chronic fetal-fetal transfusion can occur in single-oval twins, and their common placenta has vascular communication. To the palace (in the blood supply twins) hidden blood loss.

an examination

Related inspection

Obstetric B-ultrasound amniocentesis Doppler echocardiography

1. General prenatal examination

When the twins, amniotic fluid, B-ultrasound lobulated or multi-leaf placenta, vaginal small amount of bleeding accompanied by fetal distress, fetal heart rate changes are sinusoidal, it is necessary to pay attention to the possibility of the disease. A vaginal examination can detect a small, non-sliding strip on the membrane, but it is difficult to find a positive result when the cervix is not opened. Abdominal distension can be considered early in the high-level artificial rupture of membranes, such as the emergence of bloody amniotic fluid and rapid fetal distress, except for placental factors, should also consider the possibility of the disease.

2. Color Doppler ultrasound imaging

Observing the blood flow of the placenta, blood vessels and placenta adhesion, it is possible to make the umbilical cord sail attached to the prenatal diagnosis, and the vaginal ultrasound can directly observe the frontal blood vessels on the membrane, which is also helpful for early diagnosis. And have reported success.

3. Amniocentesis can directly observe the anterior blood vessels and amniotic fluid turbidity on the membrane, but there is damage to the blood vessels.

4. In addition, vaginal bleeding can be quickly collected to identify the source of bleeding

Common methods are as follows: (1) smear for Wright's staining, microscopic search for fetal nucleated red blood cells; (2) taking specimens for hemoglobin electrophoresis, if hemoglobin F is found to be mixed with fetal blood in amniotic fluid; (3) Apt-Downey test : Add sodium hydroxide to the specimen. If it is still red, the bleeding is from the fetus. If it is brown, it is maternal blood. (4) Kleihauer-Betke test: adding weak acid to the specimen and making special After staining, the smear microscopy showed that the maternal red blood cells were not hemoglobin colored and ruptured into "ghost cells", while the fetal red blood cells remained unchanged in red. This method can quantitatively estimate fetal blood loss.

Differential diagnosis

Need to be identified with the following diseases:

1. Pale asphyxia: There are many childbirth complications or intrauterine distress before birth, newborns with bruising, difficulty breathing or suspension, slow heart rate and no Hb reduction can be identified with this disease.

2. Severe neonatal hemolytic disease: may also have pale, anemia, but often accompanied by edema, hepatosplenomegaly, jaundice within 24 hours after birth, can be identified with the disease. The diagnosis of hemolytic disease requires examination by specific blood group antibodies.

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