Everything pregnant mums need to know about Amniotic Band Syndrome

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Have you heard of this rare condition? Read our comprehensive, all-you-need-to-know guide on ABS now.

Every expectant mum hopes that their little bundle of joy sees the light of the world safe and growing healthily. However, aside from infections and hereditary diseases, other developmental issues, called congenital defects, can still occur along the way. In this article, we discuss a rare defect called Amniotic Band Syndrome (ABS) – from causes to how to prevent amniotic band syndrome.

Here’s what every expectant mother should should know about this condition. 

What is Amniotic Band Syndrome (ABS)? 

ABS is a condition which occurs when you are still pregnant.

When the baby is in your womb, it is encapsulated in your amniotic sac, which contains amniotic fluid. The amniotic fluid keeps the baby afloat.

Interestingly, the amniotic sac containing the baby and fluid has two films which stick together. The exterior film which faces the uterus, is the chorion, whereas the inner film surrounding the baby is the amnion.

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How to prevent amniotic band syndrome? A diagram showing how ABS occurs. | Image Source: University of San Francisco

ABS affects an unborn baby when the amnion tears abruptly, but without damage to the chorion.

Parts of the amnion then hang loosely, like thin threads inside the amniotic sac. 

These amniotic bands can then accidentally twist and wrap around different body parts of your baby, which can affect your little one in many ways.

Depending on which body part is entangled and whether it is bound tightly,  blood flow could be constricted and impact your little one’s development.

These birth defects include:

  • Missing limbs or digits. A band that twists around a limb tightly can lead to its amputation, such that the baby is born lacking fingers and toes, or may be born with a partial arm or leg. At times, the baby is born with dead limbs which need to be removed surgically.
  • Cleft lip or palate, if the band goes across the baby’s face.
  • Clubfeet, which commonly happens with babies suffering form ABS.
  • In the worst case scenario, fetal death. If the amniotic band twists onto the umbilical cord, it cuts off blood supply. This presents a risk of miscarriage. 

How to prevent amniotic band syndrome? Is ABS serious?

Doctors assess ABS on a case-to-case basis. Its severity is influenced by where the bands have wrapped around the baby, and how tight they are.

ABS can be mild, or quite severe. However, this condition does not harm the pregnant mother in any way. Many of the issues arise after the mum has given birth, and affect the baby.

Amniotic Band Syndrome is also know by a variety of of other names: 

  • amnion rupture sequence
  • amniotic bands
  • congenital constriction rings
  • constriction band syndrome
  • Streeter bands
  • Streeter dysplasia
  • limb body wall complex
  • amniotic band sequence
  • amniotic deformity, adhesions, mutilations (ADAM) complex
  • Streeter anomaly

What causes ABS? Is it something I did while I was pregnant?

ABS is relatively rare, ranging from 1 case in 1,200 to 1 case in 15,000 live births. It is hard to study because it is so rare. It happens totally by chance, and is not genetically inherited. Thus, one baby affected by ABS won’t affect another baby in the future.

This condition is also not linked with anything you did or did not do in pregnancy. So if you’re asking yourself “How to prevent amniotic band syndrome?” there is honestly no clear answer. 

Recent research hasn’t even pinpointed an exact cause, or prenatal factors for ABS. Some small scale studies have established some links with issues below, but researchers still need to do further studies to definitely pinpoint the cause of ABS.

  • Previous surgery of the Uterus  
  • Chorionic Villus Sampling (CVS), a test which extracts the chorionic villus for genetic tests. Researchers suspect that the needle puncturing the chorion could also cause the amnion to tear. 
  • Pregnant women with exposure to Miroprostol, a drug that triggers abortion
  • Smoking and drug use while pregnant

How to prevent Amniotic Band Syndrome?

Unfortunately, there isn’t a definite method proven to prevent ABS. Although it is possible that ABS may arise due to CVS, it is still an unlikely cause of ABS.  

To ensure that your baby is not at risk of having abnormalities before birth, do heed guidelines for preconceptional care.

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How to prevent amniotic band syndrome? Is there a way? | Image Source: Screengrab from 123radiology

What are the symptoms of ABS?

In general, ABS can cause a lot problems, which range from mild issues, to complicated or even fatal ones.

Here’s a short list of how ABS could affect your baby:

  • Tightening or partial loss of fingers and toes, with some not fully developing
  • Tightening or partial loss of arms and legs, with some not fully developing
  • A large swollen area after the band is located 
  • Club hands or club feet (hands or feet that are twisted and turned inwards)
  • Cleft lip and/or palate (a crack in reaching from the lip towards the nose)
  • Facial deformities
  • Spinal deformities
  • Thoracoschisis (tightening of the thoracic wall)
  • Abdominal wall disorders
  • Encephalocele (an abnormality defined by the brain tightly poking out of the skull)
  • Anencephaly (an abnormality defined by the absence of parts of the brain and skull, leading to little or no forehead at all)
  • Tightening of the umbilical cord (blood supply form the mum goes through the umbilical cord, and tightening it leads to blockage of the baby’s blood supply)
  • Limb-body-wall complex (combination of a problem involving the limbs, and typically the chest or abdomen of the baby)

How to diagnose ABS

Doctors can diagnose ABS before the baby is born, or, more commonly, after he is born. 

Pre-birth diagnosis

Experienced doctors or specialists might be able to accurately pinpoint ABS based on an ultrasound scan. Doctors normally perform this scan in the baby’s 12th week in the womb.

If the doctor suspects that the baby has ABS, do discuss this with an experienced specialist.

Amniotic bands are minute in size and very difficult to see even with ultrasound. This often leads to misdiagnosis. An expert in ABS will be able to guide you with their professional opinions on what the ultrasound scan might mean.

Post-birth diagnosis

Once you have given birth, there are several ways your doctor can assess whether your baby has ABS or not, such as by:

  • A physical examination. Your doctor will look for deformed limbs or any other physical abnormalities with your baby. 
  • An X-Ray, to assess how deeply an amniotic band might have impacted the tissues below the skin
  • Magnetic Resonance Imaging (MRI) or other scans to further understand how the amniotic band could have influenced or injured blood vessels and nerves 
  • Other deeper tests such as targeted ultrasound (3D), Doppler Blood Flow Study or a Fetal Echocardiogram

What should I do if doctors diagnose my baby with ABS?

After your doctor undertakes a thorough examination of your baby’s condition, he will discuss potential treatment options. It is very likely that fetal surgery will be recommended for extreme cases, whereas mild cases may be treated with reconstructive surgery after giving birth. 

In general, there are a variety of treatment options for ABS:

  • Supportive therapy targeted at alleviating the symptoms (for instance oxygen or breathing support for babies with improperly developed lungs)
  • Reconstructive or plastic surgery for developmental abnormalities, such as webbed fingers or feet and cleft lip 
  • Clubfoot treatment via the Ponseti method
  • Occupational therapy so that the children are able to practice, and master, using their recovered fingers, toes, arms and legs 
  • 3D-printing prosthetics to replace the abnormally formed limbs
  • Fetal surgery, for really extreme cases of ABS in unborn babies. Fetal surgery involves severing the amniotic bands via a laser or sharp surgical apparatus while the baby is still in the amniotic sac. Normally, thorough consideration is given before choosing this option as there may be further complications afterwards.  

If your child has ABS, you will have many opportunities to discuss what surgeries you need to know about and how to better manage his or her life. Remember, if you have any concerns, always consult a medical professional.

 

References: amnioticbandsyndrome.com, University of San Francisco, rarediseases.org, Very Well Family, Seattle Children’s Hospital, 123radiology 

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