Amniotic Band Syndrome

Amniotic Banding (also known as Constriction Band Syndrome) is a very rare birth condition caused by the rupture of the amniotic sac early in the pregnancy. The amnion ruptures and then falls away, leaving the developing fetus exposed and unprotected from the fiberous tissues of the placenta. The Chorion portion of the placenta is made up of fiberous tissues which float in the waters of the uterus and can, without the protection of the anmiotic sac, become tangled in the developing appendages of the fetus, thus creating the characteristic amniotic bands that are seen on these infants.
Very little is known about the cause of the rupture. Some possibilities would include trauma, infection, or possibly some deformity in the development of that structure. Amniotic banding occurs in approximately one in every ten thousand births. However, it is believed that in most cases, the rupture that leads to amniotic banding, will most often instead lead to a spontaneous miscarriage during the first trimester. Therefore, it is unknown how often the condition that leads to amniotic banding (that is - the rupturing of the amnion) actually occurs.
Because it is not a genetic condition, the occurrence of amniotic banding is sporadic. It happens to boys and girls pretty much equally. There seems to be no familial pattern at all to the occurrence. Probably because of the way various structures are situated in utero, the banding occurs on the left side more often than on the right - however, it is not uncommon to involve the right.
The actual amniotic bands are only one of many potential birth defects that may be present in a child born with this sequence. These children also may present with congenital amputations, missing digits, fused digits, cleft lip and palate, cranial abnormalities, hemangioma, clubbed feet, etc. The type and severity of the birth defect depends largely on when the rupture occurred, how tightly the bands are tangled, what part of the fetus is tangled, etc.
Besides entanglement, some of the deformities found in amniotic banding are the result of what unprotected exposure to the developing fetus can do to the placenta. Any disruption of the placental blood flow during a critical time of embryonic development can lead to a birth defect. Therefore, it is not uncommon to find these infants with cleft lip and palate, poorly formed fingers and/or toes, syndactyly, or hemangeoma, along with the banding. Furthermore, women who are carrying a child with amniotic banding also very often have very little amniotic fluid - which then may lead to such conditions as clubbed feet.
Repair of the birth defects associated with amniotic banding depends largely on what sort of expression this condition takes.
The bands themselves are surgically released using a z-plasty type repair. This allows the flesh around the band to continue to grow as the child develops. Many times the release of one band is done in two surgeries, so as to minimize the trauma to the site.
Treatment of congenital amputation depends largely on which limb is missing - where it was amputated, and the philosophy of the doctor and the family concerning the use of prosthetic devices. When the banding is so severe as to significantly stunt the development of the limb beyond the band, a decision is often made to amputate the dysfunctional limb.
Syndactyl fingers are often separated. Many times a child with amniotic banding will have "mitten hands" - or a fusing of all four fingers on the one hand. It is rare for the thumb to be fused to any of the fingers.
Unless some of the banding affected the development of the brain, a child with amniotic banding is expected to develop normal cognitive abilities.
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