What is Amniotic Band Syndrome?
Amniotic band syndrome (ABS) is a condition that affects the development of various body parts in a baby before birth. This can lead to disruptions, deformations, and malformations of parts that were supposed to form normally (as shown in the image titled ‘Amniotic Band Syndrome’). It’s important to note that ABS is more properly referred to as a ‘sequence’ rather than a ‘syndrome’. That’s because the abnormalities seen in ABS are related to an event that could have different causes.
In comparison, a ‘syndrome’ usually refers to a group of traits that are known to be caused by a specific reason. For example, Turner syndrome, which is caused by a specific chromosomal issue. Similarly, ABS is known by many names such as amnion rupture sequence, ADAM complex (which stands for amniotic deformities/adhesions/mutilations), amniotic band disruption complex, congenital constricting bands, terminal transverse defects, and Streeter anomaly.
What Causes Amniotic Band Syndrome?
Amniotic Band Syndrome (ABS) occurs for unknown reasons. However, it’s believed that it might happen when the amnion, which is the inner sac that holds the fetus and the amniotic fluid, bursts early in pregnancy. This can create loose strands or bands, referred to as amniotic bands, that can stick to or wrap around the baby. These bands can squeeze developing organs, causing what are known as constriction rings. In extreme cases, these can disrupt the blood flow, potentially leading to the loss of a body part. If the bands stick without squeezing, they can still lead to deformities.
The cause of the amnion bursting in the first place is usually unclear. However, we do know that certain medical procedures like chorionic villus sampling (when a small piece of tissue from the placenta is taken for testing) can sometimes lead to similar symptoms. Still, this does not explain all ABS cases because sometimes the affected parts are internal organs that still have an intact lining from the amnion. In such situations, the problems might be linked to disrupted blood flow in the baby, unrelated to the bands. This could be linked to exposure to misoprostol (a medicine used for stomach ulcers and inducing labor) in the first trimester, or chorionic villus sampling done before the 10th week of pregnancy.
In a few odd cases, neither the bands nor disrupted blood flow are thought to be the cause and might result from a gene mutation. Almost all reported ABS cases in twins have been in identical twins, hinting that there could be a genetic link.
Risk Factors and Frequency for Amniotic Band Syndrome
Amniotic Band Syndrome (ABS) is not as common and occurs in approximately 1 out of 1,000 to 1 out of 15,000 live births, and also in 1 out of 70 stillbirths. It can affect both male and female newborns equally. It’s unknown if ABS can be inherited, and for the most part, every case is unique. However, there have been rare instances where more than one family member has had ABS, especially in identical twins.
Signs and Symptoms of Amniotic Band Syndrome
Amniotic Band Syndrome (ABS) is a condition that can cause a variety of physical issues and can be sorted into 4 main categories:
- Tight bands, called constrictive rings, around a body part
- Defects in the limbs, like missing fingers or toes
- Defects in the nerves or spine
- Defects in the face or head
In most cases of ABS (about 80%), the patient will have constrictive rings or missing limbs or digits. These bands can just affect the skin or go deeper into the tissues. If a band is so tight that it causes a part of the body to be amputated while the baby is still in the womb, this part usually gets absorbed back into the body and won’t be seen after the baby is born.
Limbs issues can include a tight ring around a limb with swelling, missing parts of fingers or toes (especially the ones in the middle), bent joints, or fractures. The legs are more often affected than the arms, and the thumb is usually unaffected because it stays protected by the hand while the baby is in the womb.
Though they’re not as common, ABS can also cause issues in the head or face, like brain tissue pushing out through an opening in the skull, breaks in the face, and cleft lip or palate. Sometimes, ABS can also cause defects in the spine and lead to conditions like scoliosis.
Testing for Amniotic Band Syndrome
Diagnosing Amniotic Band Syndrome (ABS), a condition caused by fibrous strings in the amniotic fluid that can potentially entangle the fetus, can be tough due to its diverse causes and ways it can present itself. It’s particularly tricky to identify before a baby is born. However, if certain major body parts appear restricted, missing or deformed, ABS might be suspected as early as the first three months of pregnancy. Swelling in the limbs of the fetus can also suggest ABS. Very rarely, a fibrous band from the amniotic fluid could be seen directly attached to tissues limiting the movement of the unborn baby.
After birth, if a newborn has visible bands, missing limbs, or unusual defects on the head, face, or on the body, ABS might be considered as a possible cause. In situations where these bands are not present, doctors will study the amniotic membranes and the placenta for a more accurate diagnosis.
Treatment Options for Amniotic Band Syndrome
There aren’t any definitive rules on how to manage Amniotic Band Syndrome (ABS), a condition that can affect a baby during pregnancy, when it is diagnosed before birth. No matter what way of dealing with ABS is chosen, all patients should be informed about any abnormalities detected in the fetus and the chance of other undiscovered abnormalities.
An option called amniocentesis, a prenatal test that allows doctors to diagnose chromosomal disorders, can show if the results could interfere with decisions about the pregnancy. It’s a good idea to have consultations with specialists that deal with the issues at hand. If the abnormalities detected are fatal, discussions should also include web how to provide comfort care for the baby after birth.
In cases where the amniotic band has wrapped around and constricted part of the baby, an in-utero procedure can potentially slow down this constriction and restore normal blood flow. The idea is that a fetus’s limb might recover better after in-utero treatment, compared to recovery after birth due to the tissue’s ability to heal better during fetal life. However, even if this intervention can restore blood flow and save the limb, plastic surgery might still be needed after birth. It’s important to remember that we still don’t know how effective this intervention is because there isn’t a clear way to choose candidates for the procedure and there isn’t enough clinical research data.
There aren’t any rules dictating how to manage a pregnancy that is complicated by fetal ABS. Follow-up care, ultrasound scans, and interventions are tweaked according to each individual case, and they depend on how severe the ABS complications are. Post-natal care includes a thorough physical exam for the baby, and if necessary, imaging studies to clearly show the extent of ABS. One way to potentially help save a limb is to get rid of constriction rings after birth, it could help to maintain some limb function by alleviating the pressure in the veins. If the blood supply is compromised after birth, urgent medical intervention may be needed.
What else can Amniotic Band Syndrome be?
When looking at the possible causes of amniotic bands, doctors generally consider two main categories:
- Issues with the uterus and placenta, which may include:
- Synechiae and septa, which are related to adhesions in the uterus that typically come from past surgeries or infections or are birth defects. These conditions don’t limit the baby’s movement and are not linked to the same anomalies as amniotic bands.
- Leftover gestational sac, which can linger after the demise of a fetus in a twin pregnancy.
- Circumvallate placenta, which refers to a placenta with a smaller than usual chorionic plate but more extracranial placental tissue growth. Similar to synechiae and septa, circumvallate placenta does not restrict fetal movement, and it does not lead to amniotic bands.
- Other reasons behind limb amputations, including:
- Various syndromes and harmful substances (teratogens) that may result in birth defects related to the limbs. For instance, the absence of a thumb or a radius (a forearm bone) can meghan examples. Some limb anomalies might also be due to exposure to teratogenic substances.
It’s crucial for physicians to consider these various options and conduct the necessary tests to make an accurate diagnosis.
What to expect with Amniotic Band Syndrome
The future health outcomes for a newborn diagnosed with ABS, or amniotic band syndrome, greatly depend on the severity of their condition. This can range from minor physical appearance issues to life-threatening malformations of crucial organs.
Possible Complications When Diagnosed with Amniotic Band Syndrome
ABS has links to multiple pregnancy complications such as miscarriages, preterm births (births that occur before the due date), and stillbirths (when a baby dies in the womb).
Complications:
- Miscarriages
- Preterm births
- Stillbirths
Preventing Amniotic Band Syndrome
Amniotic Band Syndrome (ABS) is a complex condition where different parts of a baby’s body can be affected by a range of abnormalities while they are still in the womb. These changes are believed to be caused by several factors. The main theories include the effect of bands from the amniotic sac (the fluid-filled sac that supports a baby in the womb), disruption of the baby’s blood supply, and very rare cases of genetic mutation.
ABS can lead to four main types of defects – rings of tight tissue (constriction rings), issues with arms or legs (limb defects), problems with the spine or nerves (spine/neural defects), and facial irregularities (craniofacial defects). Doctors can often detect ABS before the baby is born.
The care provided to the mother during her pregnancy depends on the severity of the ABS abnormalities in the baby. While there aren’t universally agreed guidelines for this, one potential treatment during pregnancy is to try and remove the bands stopping the baby’s limbs from developing normally. However, there’s no widely accepted way of determining which babies would benefit from this treatment.
After the baby is born, treatment might involve removing the tight bands to try to save the affected limb. In rare cases, ABS can cause severe deformities in important parts of the inside of the body, which could be life-threatening.