Postnatal surgery
This type of surgery is carried out after the baby is born and usually happens within 48 hours. Surgeons will be able to close the defect but this will only prevent further damage. Studies have shown that closing the defect earlier can prevent damage to the spinal cord and reverse or prevent complications.
The neural tube defect can be seen on the lower back of this newborn baby.
Foetal surgery
This type of surgery is carried out from within the womb between 23 and 25 weeks gestation. There are two techniques to carrying out this surgery: Open foetal and fetoscopic.
Abdomen
Fatty tissue
Uterus
Foetus with defect
Open foetal surgery
This surgical technique involves making an incision about 7cm in length across the stomach to access the uterine cavity. The womb is then brought out and another incision gives access to the foetus who is positioned for surgery. Surgery to close the defect is carried out and the incisions are sutured closed. Complications of this technique are the high likelihood that the uterine scar will rupture or not heal properly. Future pregnancies will also have to be delivered via caesarean.
Below, this section cut of a pregnant mother reveals the surrounding anatomical structures closely associated with the growing uterus. The developing baby inside is 23 weeks old and presents spina bifida. Surgery will be carried out to close the defect using the open foetal surgical technique demonstrated in the above illustration.
Bladder
Rectum
Spine
Vagina
Uterus
Fetoscopic surgery
Very small incisions are made to give access to the uterine cavity, like keyhole surgery, which is less invasive and less likely to rupture. Using instruments and a small camera, the surgeon is able to close the defect on the foetus' back and suture up the small incisions made on the uterus.
This technique is currently being tested in the UK but studies from other countries have proven its wider range of benefits in comparison with open foetal approach.
The Texas children's hospital highlights three main benefits to fetoscopic surgery in comparison to open foetal surgery:
1. Fetoscopic technique allows the parent to have a vaginal birth.
2. Pregnancies have a reduced risk of uterine rupture.
3. Delivery date is increased to between 37 and 38 weeks
The aim:
The aim of surgery is to close the defect to protect the spinal cord from damage that occurs when the amniotic fluid reaches a toxic level at 34 weeks.
The steps:
1.
The first step is usually to remove the fluid filled sac that has formed over the opening.
2.
Secondly, the next step depends on the availability of the dura mater. The meninges are what cover the spinal cord and brain to protect them, and they consist of 3 layers: Pia mater, arachnoid mater and dura mater.
The dura mater is the tough outermost layer and is thick and robust enough to be sutured around the spinal cord, forming the protective barrier absent in spina bifida. If this is not an option, a dural patch can instead be placed over the exposed spinal cord for protection.
3.
Finally the muscle and skin is pulled across and sutured shut. The animation below explores a foetus in the womb with spina bifida at 23 weeks’ gestation undergoing repair of the defect.
Fetoscopy instruments are inserted into mothers abdomen.
The foetus is moved into position and the fluid filled sac is removed.
This then reveals the spinal cord and dura mater that failed to close.
The dura mater is then sutured around the spinal cord for protection.
Finally the muscle and skin layers are sutured shut.
This short animation shows the process of repair in 3D!
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