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The amniotic sac is a thin but tough membrane that surrounds the baby while it develops inside the mother. It functions as a safe house that allows the embryo to grow undisturbed by external shocks as the sac is filled with amniotic fluid. This fluid acts as a cushion and also provides the foetus with space to move around during its early development.
What is Amniotic Band Syndrome?
While the amniotic sac is relatively safe, there are instances when this sanctuary for the foetus becomes dangerous. This is because there are instances when the fibrous strands present in the sac entangle the foetus and is known as ABS. Unfortunately, there is no definitive cause that has been discovered for ABS. However, there are multiple theories that have been put forward, two of which have gained traction.
Alternative Names of ABS Disease
Some of the other names that the disease is known as include:
- Annular band constriction
- Intrauterine amputation
- Amniotic Deformity, Adhesions and Mutilations
- Limb-body wall complex
- Streeter’s amputation
- Aberrant tissue bands
How Common is It?
The likelihood of ABS is rare with an incidence rate of 1 in 1200 live births to 1 in 15000 live births. As genetics is ruled out, the possibility of a second pregnancy leading to ABS is minimal, making it even rarer.
Causes of ABS
There are several causes of ABS. Here are some you should be aware of
- Extrinsic Theory: This is the widely popular theory. The amniotic sac is composed of an outer and inner layer; sometimes, without any damage to the outer layer, the inner wall linings tear and start floating in the amniotic fluid. This presents a dangerous situation for the foetus as the bands of the membrane can get entangled on its fragile and growing body.
- Intrinsic Theory: The above theory however does not explain all ABS conditions such as cases where the amniotic sac is intact, but ABS persists. This theory suggests that it is poor blood flow that causes the deformities but fails to explain the reason for the poor blood flow.
Signs and Symptoms
Some of the probable ways of knowing if your child has ABS include:
- Crease marks on parts of the body of your child such as the hand, legs or fingers
- A gap on the head or torso
- The size of the limbs is unequal
- Swelling of different parts of the body due to the wrapping of the bands
The effects of amniotic band syndrome vary from case to case. Below are some of the issues that the baby would have if they have ABS:
- Limbs are of different length
- The fingers or toes are webbed
- The fingers or toes are fused together
- Nails are deformed
- When the band gets wrapped around the umbilical cord or the head resulting in the death of the foetus.
- The band can get entangled around one of the legs and restrict its mobility which can lead to clubbed feet.
- The bands can get tightly wrapped around one of the limbs to an extent where the blood flow is constricted. This can lead to possible amputation of the limb.
- There are crease marks on the skin due to the entanglement
- The baby is born with the bands still attached to their bodies.
- Cleft lip and palate
How is the Diagnosis Done?
For diagnosing amniotic band syndrome ultrasound is conducted around the third month of pregnancy. The bands themselves are fine and it may be difficult for the obstetrician to spot them. A deduction is made by looking at any deformities that are associated with ABS.
The treatment for ABS depends on a host of factors such as area affected, the extent of damage and the stability of the child.
- Clubfeet: This can be corrected with the help of casts
- Cleft Lip And Palate: Reconstructive surgery when the child is 3-6 months old. Other factors such as the extent of damage and the infant’s feeding capabilities also need to be taken into consideration.
- Webbed Fingers: Amniotic band syndrome hand surgery after birth is the preferred option for those with webbed digits.
- Missing Limbs: Prosthetics can be used for those who lose a large part of their legs or hands. 3D printing has also become very popular as models can be made with anyone with a 3D printer and an internet connection.
Management of ABS During Pregnancy
Once it has been established that stray bands of amnions are present, the situation must be monitored closely. If the bands are not touching the foetus, there is no intervention that is required. However, if the bands are life-threatening or can cause deformity, a surgery called foetoscopy is recommended. The surgery involves a small incision in the abdomen through which a tiny camera is inserted to look inside the amniotic sac. A laser is then used to cut the entangled bands to reduce pressure and allow the healthy development of the foetus.
Special Consideration During Childbirth with Amniotic Band Syndrome
Due to the possible complications involved, below are some of the precautions that must be taken if your baby is under the risk of ABS.
- A caesarean section is the preferred method of delivery to avoid further entanglement. Have multiple sessions with your doctor in advance to educate yourself on the risks involved for you and the child.
- Some hospitals may not be equipped with the requisite facilities to take care of the afterbirth needs of a baby with ABS. For instance, surgeries are conducted on newborns as early as three days after birth to remove the bands.
- It would be unwise to request for inducing an early delivery for every case of ABS. This form of delivery is only applicable when the bands get entangled with the foetus towards the end of the pregnancy and pose a health risk.
Knowing that your unborn baby has ABS may be a little frightening at first. However, once the syndrome is understood it becomes apparent that it can be managed through continuous monitoring.
Also Read: Polyhydramnios