Amniotic band syndrome (ABS) is a rare condition that affects some babies during pregnancy. It occurs when the amniotic sac, which normally surrounds and protects the baby in the womb, becomes damaged and forms loose bands of tissue. ABS can cause serious birth defects or even death of a baby if it wraps around a baby's limbs or other body parts and interferes with blood flow and growth.
The exact cause of ABS is unknown and controversial. There are two main theories about how it happens:
As a result of external factors, such as drugs, prenatal tests, or open fetal surgery, the amniotic sac becomes damaged, causing bands to break off and enter the amniotic fluid.
In some fetuses, the amniotic sac remains intact but has circulation problems due to an abnormal gene or other factors. This causes the bands to form and affect blood flow.
ABS symptoms vary depending on how severe it is and which body parts are affected. Some babies may have mild symptoms that do not appear until after birth. Others may have more serious complications that require immediate medical attention.
The most common symptoms of ABS are:
Limb abnormalities: The arms or legs may be shorter than normal, have extra joints or fingers or toes, have webbing between them, or have missing digits.
An abnormal limb may be shorter than normal, have extra joints, fingers, or toes, or have webbing between themer lip or roof of the mouth), or have a brain malformation.
An abnormal head may be smaller than normal, have an extra ear or eye opening (fenestration), have a cleft lip or palate (a split on the upper lip or roof of the mouth), or be malformed on the brain), or have a missing eye (anophthalmia).
Abnormalities of the face include an asymmetrical face, a small mouth or nose (micrognathia), a cleft lip or palate (a split in the upper lip or roof of the mouth), or ptal defect), or have a narrowing of one chamber (pulmonary stenosis).
ABS is usually diagnosed before birth by an ultrasound examination. An ultrasound can detect any abnormalities in a baby's limbs, head, facial, or internal organs.
Sometimes ultrasound may not be able to detect all cases of ABS because some bands may be too small to see on screen. In these cases, other tests may be needed to confirm the diagnosis.
Some tests that may be used to diagnose ABS include:
Amniocentesis: A procedure that involves taking a sample of fluid from inside the amniotic sac using a needle. This test can show if there are any abnormal cells in the fluid that indicate fetal distress.
Fetal echocardiogram: A test that uses sound waves to create images of the baby’s heart. This test can show if there are any defects in the heart structure or function.
Fetal MRI: A test that uses magnetic fields and radio waves to create detailed images of the baby’s brain and other organs. This test can show if there are any malformations in these organs.
ABS is treated depending on the severity and body part affected. The main goals of treatment are to prevent further damage to the baby's development and to improve its quality of life.
The treatment options for ABS include:
Surgery: A procedure that involves removing some parts of affected limbs using microsurgery techniques. Surgery can correct some limb deformities but not all.
Prosthetics: Artificial devices that replace missing limbs such as hands, feet, arms, legs, eyes, ears, nose, mouth, etc. Prosthetics can improve mobility and appearance but not function.
Rehabilitation: Physical therapy and occupational therapy that help improve motor skills and daily activities for children with limb deficiencies.
Medication: Drugs that help treat pain relief for children with limb injuries.
Supportive care: Caregivers who provide emotional support and guidance for families affected by ABS.
There is no sure way to prevent ABS because its exact cause is unknown. However, some possible ways to reduce its risk include:
Avoiding drugs such as misoprostol during pregnancy unless prescribed by a doctor.
Avoiding prenatal tests such as chorionic villus sampling (CVS) or amniocentesis unless necessary for medical reasons.
Avoiding open fetal surgery, which is reserved for serious, life-threatening fetal conditions only.
You should talk to your doctor about how you can monitor your baby's health and development during pregnancy if you have a history of ABS or other risk factors. You should also report any signs of fetal distress or abnormality to your doctor immediately.
