Amniotic band syndrome
Introduction
Introduction to amniotic membrane syndrome Amniotic band syndrome (Amniotic Bandsyndrome) has many names, such as congenital annular adhesion zone, cobweb syndrome, etc., which refers to partial amniotic membrane rupture to produce fiber bundles or fiber sheaths, which cause adhesion of embryos or fetuses to amniotic membranes, restraint, compression, and entanglement. The fetus causes the fetal affected organs to divide or develop malformations. Commonly affected parts are the head, torso and limbs. There are many types of malformations, ranging from small deformities of the hands, feet or fingers (toes) to complex malformations of multiple body parts. basic knowledge Probability ratio: 0.3% of specific population Susceptible population: pregnant women Mode of infection: non-infectious Complications: spinal deformity
Cause
Cause of amniotic band syndrome
Spontaneity factor (25%):
In the early pregnancy, the amniotic membrane is ruptured and the choriomes are intact. The fetus reaches the chorionic cavity through the rupture of the amniotic membrane. Because of the better permeability of the chorion, the extravasation of amniotic fluid, the transient amniotic fluid is too small, the fetus is close to the chorion, and the villi are The membrane tissue has the ability to proliferate and infiltrate, and after contact with various tissues of the fetus, the tissue to be contacted is destroyed, and then the deformed portion of the corresponding part appears. Amniocentesis rupture occurs in early pregnancy, mid-pregnancy, late stage, especially in the third trimester of pregnancy, usually does not cause amniocentesis, amniocentesis in the third trimester, and there is a hole in the amniotic membrane due to puncture after puncture, but It has been confirmed that amniocentesis at this time does not cause amniocentesis.
In recent years, the advancement of fetal medicine, especially fetal surgery, has successfully performed intrauterine amnion band release treatment on amniotic membrane syndrome. After the operation, the affected limbs can get rid of the amniotic band and restore normal development.
Genetic factors (25%):
Although amniotic membrane syndrome is related to amniotic membrane, no direct evidence of amputation or deformity caused by amniotic membrane has not been found. Therefore, some scholars believe that the root cause of amniotic membrane syndrome is genetic abnormality, that is, genetic material deficiency.
Visceral malformation (20%):
Amniotic membrane syndrome often combines complex visceral malformations. A variety of complex visceral malformations are difficult to explain with the theory of amniotic membrane rupture. In the absence of amniotic membrane rupture, animal models of amniotic membrane syndrome can be established by applying vasoactive substances.
Pathogenesis
1. Chorionic tissue fibers wrapped around the fetal limb can cause carcass malformation and skin defects; fiber band and defect skin adhesion, can lead to abdominal fissure or brain swelling and other deformities; fetal chewing swallowing amniotic membrane, can appear asymmetric cleft lip, The face is cracked or the digestive tract is blocked.
2. The mechanical compression or restraint of the amniotic membrane should also be one of the mechanisms of amniotic band syndrome. It should be emphasized that the time of the amniotic membrane affecting the fetus may not be limited to the early pregnancy, but should also play a role in the middle and late pregnancy. Because the amniotic membrane was released after the middle and late pregnancy, the affected limbs returned to normal development.
3. In the early stage of the embryo, due to abnormal genetic material, the internal line-like germ is disordered or the connective tissue of the limb is abnormally developed, which eventually leads to various deformities.
4. In histological studies, it was found that vascular rupture and hemorrhage occurred earlier than intrauterine limb amputation and abdominal fissure. Therefore, some scholars have proposed the hypothesis that the mesenchymal cells and epithelial cells of the superficial blood vessels of the amniotic membrane are damaged. The rupture of the germ layer, secondary to limb amputation, brain swelling and finger (toe) foot (hand) and other deformities.
Prevention
Amniotic membrane syndrome prevention
Due to the different parts and extent of fetal malformation, the treatment is not the same. For small adhesions and lymphedema of the fingers and toes, the prognosis is better. If there are deformities of the limbs, the deformity is more serious, and multiple deformities are often fatal. In recent years, there have been more reports that the limbs can be restored to normal development after the application of the fetal lens to release the amniotic membrane. The pregnant women should be reminded to do perinatal care, try to prevent intrauterine infection, if there is trauma or medical diagnosis after amniocentesis Regular ultrasound examinations are performed. If you can perform ultrasound examination routinely in the middle of pregnancy and strengthen the identification of the disease, early diagnosis and treatment will be of great significance for improving the quality of perinatal children.
Complication
Amniotic membrane syndrome complications Complications spinal deformity
In the early pregnancy, the amniotic membrane is ruptured and the choriomembranes are intact. The fetus reaches the chorionic cavity through the rupture of the amniotic membrane. Because of the better permeability of the chorion, the amniotic fluid is extravasated and the oligohydramnios is too close to the chorion. The chorionic tissue has the ability to proliferate and infiltrate, and the contact with the various tissues of the fetus destroys the contacted tissue and then deforms the corresponding part.
Symptom
Amniotic membrane syndrome symptoms Common symptoms Fetal growth retardation Limb shortening deformity Fetus distress Short head deformity Lip folds Increase deformity Long head deformity
There were no special clinical symptoms and signs during pregnancy, no significant reduction in amniotic fluid, and normal uterine growth rate.
Clinical features: Amniotic membrane syndrome has the characteristics of low incidence, sporadic, etc., no specific clinical, no clinical symptoms and signs in the first trimester, no obvious oligohydramnios in the early and middle stages of pregnancy, and no abnormal growth rate of uterus.
Examine
Amniocentesis syndrome examination
The diagnosis of amniotic band syndrome is mainly based on imaging examination, including B-mode ultrasound and magnetic resonance imaging (MRI).
1. B-ultrasound: This is an important method for diagnosing amniotic membrane syndrome. The following points should be noted in the process of B-ultrasound diagnosis of amniotic band syndrome.
(1) B-ultrasound diagnosis of amniotic band syndrome First, a variety of fetal malformations were found under B-ultrasound, often with too little amniotic fluid.
(2) Careful examination, irregular banded echoes in the fetal malformation or other parts, the attachment points are located in the amniotic membrane or the carcass.
(3) B-ultrasound to further clarify the type of fetal malformation.
2. Magnetic resonance technology: MRI technology has been successfully applied in obstetrics. The biggest advantage compared with B-ultrasound is high resolution, spatial resolution of organs and resolution of tissue structure, scanning thickness, gas content and The influence of bone organs is small. The resolution of MRI technique on the organs of the uterus, placenta, amniotic fluid and fetus, and the organs and tissues of the non-reproductive system around the uterus is significantly higher than that of B-ultrasound. MRI scan is not obese and enlarged by pregnant women. The effect of the uterus of the pregnancy, in the above two cases, the structure of the distal end of the B-ultrasound probe is unclear; the MRI technique is not affected by the gas in the intestine and the bony part of the pelvis. Domestic MRI technology is rarely used in obstetrics, and has been widely used in foreign countries, but it is still used as an auxiliary technology for B-ultrasound technology. There are already cases in which MRI technology has been successfully diagnosed in amniocentesis syndrome in foreign countries. It is recommended that B-survey be suspicious or discover the fetus. For deformities, MRI must be performed.
Diagnosis
Diagnosis and differentiation of amniotic band syndrome
diagnosis
Diagnosis can be performed based on clinical manifestations and examinations.
Differential diagnosis
1. Amniotic membrane: consists of 2 layers of amniotic membrane and 2 layers of chorion, with free edges and thick base. Sometimes blood flow is visible, which is thicker than amniotic membrane. Causes: 1 intrauterine device operation injury, 2 uterine cavity adhesion, chorion Along the intrauterine scar growth, the amniotic membrane does not adhere to the carcass, does not cause deformity, can disappear in the third trimester, the amniotic membrane is mainly identified with the amniotic membrane, and other needs to be distinguished from the amniotic membrane are the mediastinum and twin pregnancy of the incomplete mediastinal uterus. Amniotic membrane between the amniotic cavity.
2. Extraembryonic cavity: During normal development, the amniotic membrane and chorion are not completely fused, and the amniotic membrane and subchorionic effusion form an extraembryonic cavity, which is characterized by intact amniotic sac and no attachment to the carcass, and fetal fetal movement is not limited. Without fetal malformation, the extraembryonic cavity usually disappears at 16 weeks of gestation.
3. Short umbilical syndrome: Also known as the lower abdominal visceral with lower limb deformity, complex abdominal deformity of the abdominal wall, when the embryo develops for 4 to 6 weeks, the embryonic tissue is incomplete or defective due to blood flow changes, causing hemorrhage and necrosis in the body. Hypoxia and abdominal wall closure failure, similar to amniotic membrane syndrome, short umbilical syndrome has obvious umbilical cord short or no umbilical cord, obvious scoliosis, abdominal cavity content reaches the extraembryonic cavity, combined with multiple joint deformities of the limbs and limbs, etc. In addition, the amniotic membrane echo is not seen in the lower uterine cavity of B-ultrasound.
4. Outer amniotic pregnancy: The cause is similar to the external factor of amniotic membrane syndrome. The amniotic membrane ruptures, the fetus grows into the extraembryonic cavity, the rupture time of the amniotic membrane is later, and the amniotic membrane and the villi lose their viscosity and will not adhere to the fetus. Therefore, there is generally no fetal malformation.
