Amniotic Band Syndrome

What is amniotic band syndrome?

Amniotic band syndrome (ABS) occurs when loose bands of tissue from the amniotic sac get wrapped around the fetus during pregnancy. These pieces of tissue are called amniotic bands, and they develop when the amnion (a layer of the amniotic sac) becomes damaged. This damage causes the amnion to “shed” bands of tissue which then can tangle around the fetus.

The bands can prevent blood from reaching the fetus’s body parts, affecting how they grow. It can also affect its internal organs and the umbilical cord. ABS can lead to birth defects (congenital disorders) or loss of limbs (amputation).

The severity of ABS depends on how tight the bands are and their location on the fetus’s body. Some infants are born with mild indentations on their skin, while others are born with missing limbs, fingers or toes. When loose bands restrict blood flow from the placenta, it could result in death.

Healthcare providers can detect ABS on a prenatal ultrasound, but most diagnoses happen at birth. ABS occurs in about 1 out of every 1,200 to 15,000 live births.

Other names for amniotic band syndrome are:

• Amniotic band sequence
• Constriction band/rings syndrome
• Amniotic band disruption complex
• Congenital constricting bands/rings
• ADAM complex (amniotic deformities/adhesions/mutilations)
• Streeter anomaly

What are the signs of amniotic band syndrome?

The signs of ABS depend on where the bands attach and how tightly they’re wrapped around the fetus. Most cases (about 80%) involve damage to the hands or feet. But the bands can also tighten around the head, neck or abdomen.

Sometimes, ABS is mild and only restricts blood flow to the surface of the skin. This could result in a baby being born with constriction rings (skin indentations) or mild malformations of their limbs. Other times, the bands are so tightly wound and deep that they cut off circulation to an organ or body part entirely. This can lead to amputation, loss of blood supply or life-threatening complications.

Other symptoms of ABS are:

• Missing fingers, toes or limbs.
• Syndactyly (webbing or fusion between fingers or toes).
• Shortened or underdeveloped limbs.
• Swelling in the areas affected by the bands.
• Clubfoot.
• Cleft lip and cleft palate.
• Bone deformities, including scoliosis.
• Choanal atresia (underdeveloped nasal passage).
• Microphthalmia (small or underdeveloped eyeballs).

What are the complications of ABS?

ABS can cause complications, some of which are lifelong. Some complications of ABS can be serious or life-threatening, such as:

• Encephalocele (openings in the skull)
• Openings or defects in the abdomen or chest
• Damage to vital body systems like the gastrointestinal (GI) or genitourinary system
• Umbilical cord complications (when the band restricts blood supply to the fetus)

ABS often causes a premature birth, which can have its own risks. There’s also an increased risk of miscarriage or stillbirth.

Children with ABS may need physical or occupational therapy support for several years or until they adapt to the challenges of missing or underdeveloped limbs.

What causes amniotic band syndrome?

Most research shows that amniotic band syndrome has no clear cause other than damage that occurs to the amnion (the lining of the amniotic sac).

Causes of amniotic sac damage may include:

• Prenatal tests such as chorionic villus sampling (CVS) or amniocentesis. These tests puncture the amniotic sac with a needle to get a sample of fluid or tissue from the fetus. Damage from these tests is rare.
• Open fetal surgery. This is for serious, life-threatening fetal conditions only.

But in some cases of ABS, the amniotic sac is intact and not the cause. So, other experts believe ABS is the result of circulation (blood flow) problems in the fetus. It’s possible that some fetuses have an abnormal gene that makes them more likely to have poor circulation.

What are the risk factors for amniotic band syndrome?

You may be more likely to have a fetus with ABS if you:

• Have pregnancy complications
• Have vascular Ehlers–Danlos syndrome
• Smoke during pregnancy
• Use drugs that aren’t prescribed to you or take certain medications during pregnancy

How is amniotic band syndrome diagnosed?

A healthcare provider usually diagnoses ABS soon after birth when they examine your baby. Sometimes, a provider detects signs of ABS on a pregnancy ultrasound. An ultrasound can show lines from the tightened bands of tissue. More often, though, the ultrasound will show missing limbs or body parts that aren’t growing.

How early can you see amniotic band syndrome on an ultrasound?

Signs of ABS may be visible as early as 12 weeks into a pregnancy, but this is very hard to see. More often, your prenatal care provider notices signs of ABS at your 20-week anatomy scan. If your pregnancy care provider suspects ABS, they may order additional imaging tests like an MRI (magnetic resonance imaging).

How is amniotic band syndrome treated?

Treatment typically happens after your baby is born. The exact treatment depends on the location of the bands and how tight they were.

Mild cases of ABS may only need careful monitoring by a healthcare provider. But severe ABS that affects organ function needs immediate treatment.

Sometimes, surgery can correct issues such as club foot, cleft lip and palate or webbing. Infants or children with missing or shortened limbs may benefit from prosthetics (artificial body parts). Physical therapy and occupational therapy can help them use the prosthetic and improve their overall function.

In rare cases, a healthcare provider may remove amniotic banding with surgery when the fetus is still in your uterus (fetoscopy). The goal of surgery is to release the constrictive bands so they don’t cause further damage. This procedure carries serious health risks for the birthing parent and fetus. It’s usually only for constriction bands that are life-threatening.

Can babies survive amniotic band syndrome?

Yes, most babies survive ABS. Survival depends on factors like the location of the bands and how tight the bands were.

Will the amniotic bands disappear?

No. In most cases, the indentations or scars from the amniotic bands don’t go away. This depends on how deeply the bands embedded themselves into the skin. Ask your healthcare provider about potential treatment options for scarring due to ABS.

How can I prevent amniotic band syndrome?

There’s no way to prevent amniotic band syndrome. Healthcare providers believe that most cases are random.

What is the outlook for amniotic band syndrome?

The outlook for babies with mild ABS is good. Children with congenital (present at birth) limb conditions typically adapt well to prosthetics and rehabilitation. Babies with severe organ damage due to restricted blood flow through the umbilical cord usually don’t survive. About 1 in 70 stillbirths occur due to ABS.

What should I do if my child has amniotic band syndrome?

Children with ABS will need a strong support system and long-term care. Parents, family members and healthcare providers can help them as they adapt to the cosmetic and functional challenges of ABS. Your child may see a variety of specialists for ABS like orthopedic surgeons, neurologists and others (depending on which body parts are affected). Families and siblings may benefit from support groups.