Amniotic band syndrome are fibrous connective tissue threads originating from the amniotic membrane and stretched between the walls of the uterus. They occur as a result of small damage to the amnion in the early stages of pregnancy, violations of fetal-placental blood flow and intrauterine infections. As a rule, this disease proceed favorably and do not pose a threat to fetal development. In some cases, the fetus and the umbilical cord can be squeezed and pulled, causing malformations. The diagnosis is established on the basis of instrumental research data. With the threat of fatal compression of the umbilical cord or vital organs, intrauterine removal of the cord is carried out. In other cases, treatment is not required.
P02.8 Fetal and newborn lesions caused by other chorion and amnion abnormalities
Amniotic band syndrome are fibrous filaments consisting of connective tissue. They are a duplication of the amniotic membrane stretched between the walls of the uterus. According to various data, 0.12 – 0.015 cases of successfully full-term pregnancy are detected. They are believed to be the cause of 178:10,000 cases of miscarriages. Disease are diagnosed no earlier than 12 weeks of gestation, in 80% of cases they do not affect the course of pregnancy in any way and do not cause fetal malformations.
In 70% of cases, strands are not detected during repeated instrumental studies, which is due to their rupture or compression. In some cases, persistent amniotic band syndrome can cause the appearance of amniotic constrictions, cause fetal hypoxia, deformities and congenital amputations of limbs. Diagnosis and treatment of amniotic band syndrome are carried out by specialists in the field of obstetrics and gynecology. Neurologists, orthopedists, surgeons, ophthalmologists and other specialists are engaged in the treatment of the consequences of intrauterine hypoxia and malformations caused by this pathology.
The causes of the development of amniotic constrictions have not yet been precisely established. There are several theories explaining the occurrence of this pathology. Followers of the first theory believe that amniotic band syndrome are formed with micro-injuries of the amnion at 4-18 weeks of gestation. Connective tissue threads separated from the fetal bladder and floating freely in the amniotic fluid can entangle the umbilical cord or various parts of the fetus. Subsequently, the size of the fetus increases, but the size of the amniotic band syndrome does not change, and this causes compression of various parts of the fetal body.
Proponents of the second theory suggest that the cause are vascular disorders. Followers of the third theory point to a possible connection between amniotic constriction syndrome and intrauterine infections.
Among the additional predisposing factors for the development of amniotic band syndrome are:
- lack of water,
- isthmic-cervical insufficiency,
- malformations of the mother’s genitals,
- invasive studies during pregnancy;
- teratogenic effect of certain medications.
There is also a genetic theory of the occurrence of amniotic band syndrome, however, most modern specialists do not share this hypothesis, pointing to the lack of evidence of inheritance of this pathology. Gynecologists say that the probability of amniotic band syndrome does not correlate in any way with the age of a pregnant woman, the number of previous births, the presence of amniotic adhesions during previous pregnancies and the existence of a similar pathology both on the maternal and paternal side.
The most common consequence of the strings of Simonar are annular indentations in the extremities. Distal parts usually suffer. Most often, with amniotic band syndrome, the II, III and IV fingers of the hands are affected, less often there are constrictions in the area of the I toe. One or more limbs may be affected. There are also multiple constrictions of one limb at several levels. Amniotic band syndrome form deep furrows on the surface of the limb, sometimes reaching the bone. Subsequently, these furrows, which prevent normal blood and lymph circulation, cause the development of trophic ulcers, elephantiasis and partial gigantism of the limb.
Due to compression of peripheral nerves with amniotic band syndrome, paresis and paralysis may develop, accompanied by muscular atrophy. In severe cases, due to gross violations of blood flow, the distal part of the limb is necrotized and either rejected in the prenatal period, or requires amputation after birth. With rejection in the intrauterine period, the dead part of the limb separates from the fetus and floats freely in the amniotic fluid.
In addition,amniotic band syndrome in the extremities can cause syndactyly, myopia, false joints, joint contractures, nail deformities, violations of the shape and size of the limbs. The connection between amniotic band syndrome and congenital clubfoot has been established. Amniotic constriction syndrome is detected in every third child with this pathology. The reason for the development of clubfoot is presumably the restriction of the mobility of the limb due to its fixation by constriction and compression of the leg by the uterine wall.
In 12% of cases, amniotic band syndrome cause deformities of the face and skull. There may be deformities of the nose, non-thickening of the upper lip and palate, strabismus, an increase in the distance between the eyes, drooping eyelid, underdevelopment of the eyeball, a decrease in the size of the eyeball, iris coloboma, corneal metaplasia, obstruction of the lacrimal glands or a violation of the calcification process of the skull. With the location in the trunk area, gastroschisis (a cleft in the anterior wall of the abdomen through which internal organs fall out) and omphalocele (hernia of the umbilical cord) may develop. Possible compression of the umbilical cord, accompanied by fetal hypoxia. It is also believed that in the presence of amniotic band syndrome, the likelihood of premature birth increases.
The diagnosis of amniotic band syndrome is made according to the results of ultrasound. Constrictions can be seen no earlier than 12 weeks of pregnancy (sometimes later). In some cases, connective tissue threads are too thin and are not detected during ultrasound scanning. In such cases, the diagnosis of this disease is established by indirect signs – deformity of the limb, an increase in the distal limb due to edema, etc. Overdiagnosis is possible.
To clarify the diagnosis, assess the severity of the threat to the fetus and determine the tactics of treatment of patients with suspected amniotic band syndrome, they are sent for additional studies: fetal echocardiography, MRI and 3D ultrasound. In most cases, amniotic constrictions do not entail consequences for fetal development and do not disrupt the course of pregnancy. In 70-80% of cases, the cords are independently torn, squeezed or resorbed and are not detected during repeated ultrasound.
Treatment is usually not required. Doctors monitor, periodically prescribe repeated instrumental studies. If there is a threat to the life of the fetus (compression of the umbilical cord or vital organs), surgical interventions are performed for intrauterine dissection of amniotic band syndrome. Such operations have appeared quite recently and are still more experimental than a standard method of treating amniotic band syndrome, however, cases of their successful completion have been described.
The tactics of treatment of a child with congenital malformations caused by the presence of amniotic band syndrome are determined individually. With deep indentations in the extremities that interfere with normal blood and lymph flow, dense scar tissue is excised during the first year of life. With syndactyly, the separation of fingers is performed, with clubfoot and myopia, conservative and surgical treatment is carried out. In amputations due to amniotic band syndrome, prosthetics of the limbs are performed.
Cleavage of the palate and upper lip usually requires several surgical interventions (from 2 to 7, depending on the severity of the pathology). The operations are performed in stages, the age of cheiloplasty and uranoplasty is also determined individually, but all experts believe that treatment and rehabilitation for this pathology must be completed before the age of six. Children with eye pathology developed as a result of this disease are referred to an ophthalmologist, depending on the nature of the defect, both conservative therapy and surgical treatment may be required. Surgical interventions are indicated for gastroschisis and omphalocele.