Disease Description
Fetal anomaly is a structural or chromosomal abnormality that occurs in the fetus in utero. It is a type of birth defect and a major cause of perinatal death. B-mode ultrasound screening between 18 and 24 weeks of gestation can detect some common fetal anomalies. And timely detection of severe fetal anomalies and induction of labor is one of the most important means to improve the quality of the birth population. The incidence of human birth defects is about 15 per 1,000 in foreign countries and 5.6% in China in 2012 according to the latest statistics from the Ministry of Health. There are many kinds of fetal malformations and various pathogenic factors, nearly hundreds of single gene diseases, this article is only a brief introduction to the general situation of fetal malformations malformations.
The classification of fetal malformation
There are many kinds of fetal malformations, among which the more common malformations include
1, central nervous system abnormalities
Anencephaly (anencechalus) is caused by the failure of the closure of the anterior neuropore and is the most common type of congenital fetal malformation, almost half of the fetuses with neural tube defects are anencephalic. Once anencephaly is diagnosed. The fetus should be induced as soon as possible. If vaginal delivery is difficult, fetal destruction can be performed to end the pregnancy.
Spina bifida is a condition in which part of the spinal canal is not completely closed. The injury is mostly posterior and occurs mostly in the thoracolumbar region. It is also the most common type of neural tube defect, with significant geographic and racial differences in incidence. There are 3 types of spina bifida.
① occult spina bifida ;
(ii) spinal cord spondylolisthesis;
(iii) spina bifida. Invisible spina bifida is often difficult to detect on prenatal B-mode ultrasonography. Larger spina bifida is more easily detected by prenatal B-mode ultrasound, and the best time to detect it is between 18 and 20 weeks of gestation. Severe spina bifida should be terminated before the diagnosis of a viable baby.
Hydrocephalus (hydrocephalus)
Hydrocephalus is the blockage of cerebrospinal fluid flow due to the failure of cerebral aqueducts, which causes a large amount of accumulation in and outside the ventricles, resulting in dilatation of the ventricular system and increased pressure, an increase in the volume of the cranial cavity, a widening of the cranial suture, and an enlargement of fontanelle, often compressing normal brain tissue. Hydrocephalus is often accompanied by deformities such as spina bifida and clubfoot. Severe hydrocephalus can cause obstructive obstructed labor, uterine rupture, and genital fistula, which can be a serious risk to the mother. B-mode ultrasonography at 17-22 weeks of gestation is useful for diagnosis. In addition, fetal magnetic resonance imaging is necessary to complement and definitively diagnose fetal malformations, especially central nervous system malformations and to identify cerebral hemorrhage and hydrocephalus. If the diagnosis is confirmed in the middle of pregnancy, induction of labor should be recommended, or if the fetus is expected, intrapartum fetal or neonatal hydrocephalus drainage may be considered.
Other malformations include: dilated lateral ventricles, cerebellar earthworm agenesis, corpus callosum agenesis, etc.
2. Congenital heart disease (congenital heart disease for short)
It is a common fetal malformation with an incidence of about 8 per 1,000, among which the incidence of severe congenital heart disease is about 4 per 1,000, mainly including: tetralogy of Fallot, large vessel dislocation, ventricular septal defect, atrial septal defect, single atrium single ventricle, etc. Ultrasonography is an important tool to screen for precordial disease during pregnancy. Termination of pregnancy is recommended in severe and complicated precardiac disease such as single atrium single ventricle. Generally precardiac disease is treated in utero or after birth.
3.Abdominal malformations and abnormalities
Atresia of the digestive tract
These include esophageal atresia, gastric pyloric obstruction, duodenal atresia, jejuno-ileal atresia, and anal atresia. Most of them can be treated surgically in the neonatal period.
Umbilical hernia and abdominal wall cleft
These are abdominal organs that protrude through the anterior abdomen due to fetal abdominal wall defects, and the prognosis is generally poor if the protrusion contains the liver. Fetal surgery during delivery or neonatal surgery can be performed to correct them.
4.Thorax malformation
Cystic adenoma of the lung
Congenital cystic adenomatoid malformation (CCAM) is a common developmental abnormality of the fetal thorax due to abnormal proliferation of fine bronchi in the lungs forming a cystic or solid intrapulmonary lesion. The incidence is approximately 1/3500-1/2500, and the prevalence and use of ultrasound during pregnancy has led to a gradual increase in the detection of this condition during pregnancy.
Diaphragmatic hernia
Diaphragmatic hernia is due to partial defect of the septum muscle and herniation of abdominal organs into the thorax through the fissure on the septum muscle. The entered abdominal organs are mostly stomach and intestine, which compress the lung tissue and affect the development of lung tissue. Severe diaphragmatic hernia can cause mediastinal shift, which can affect fetal venous return and swallowing of amniotic fluid, and can lead to fetal edema, hydrothorax, and excess amniotic fluid.
Isolated lung
Isolated lung is also known as pulmonary isolation syndrome, pulmonary segregation or parapneumonia. It is one of the congenital malformations of the lung and is an embryonic development based on abnormal vascular development. In a defective isolated lung, the lung tissue is not connected to the trachea and is supplied with blood from the body rather than the lung, as if it were a piece of lung tissue that is “isolated from the air”. It is most commonly found between the left lower lobe of the lung and the septum.