Fetal Surgery for Open Spina Bifida
What is it?
Prenatal surgery for fetal spina bifida was proven to be advantageous compared to postnatal surgical treatment in light of the improved neurological structural and functional motor outcomes in neonates and infants, as shown in Management of Myelomeningocele Study (MOMS). Doubled chances of independent ambulation was associated with higher odds of hindbrain herniation reversal and significantly reduced need for post-partum ventriculoperitoneal shunting, in patients undergoing prenatal repair versus postnatal. This is a multidisciplinary surgical procedures involving obstetric-gynaecological surgeons, expert of fetal imaging and ultrasound diagnosis, pediatric neurosurgeons and anestesiologists.
When is this procedure indicated?
Fetal surgery is indicated for all pregnant patients in which the fetus is affected by isolated Open Spina Bifida (spina bifida with no associated structural or genetic problems), at toracic or lower level. In order to be eligible the fetus should present Arnold-Chiari associated to the spinal defect. The procedure can be carried out at at 18 to 26 weeks (mean 22 weeks). The earlier the intervention, the lower the surgical risks and the higher the effectiveness of the procedure. It is ideal to get contact with the center as soon as possible in order to have enough time for the required investigations and discussions.
How is it performed?
Step 1
The procedure involves a skin incision identical to that used for normal cesarean section (Pfannenstiel incision). The uterus is extracted and the fetus positioned under ultrasound guidance, exposing the defect to the region of interest. A 2.5 – 3.5 cm incision on the uterus is carried out (mini-hysterotomy), the fetus remains in the whomb and a running suture ia done to secure amniotic membranes to the uterus (myometrium).
Step 2
A pediatric retractor exposes the defect allowing the neurosurgeon to repair the defect with three layers and microscope (identical method to that usually done postnatally).
Step 3
At the end of the fetal phase the amniotic sac is filled with warm saline solution and a multiple layer closure of the uterus and abdominal wall is carried out.
Recovery
Full recovery after surgery requires about 1 week with the need of weekly outpatients follow-up visits in the first 4-6 weeks and then every 2 weeks if uncomplicated until delivery. Elective cesarean section is planned at term or earlier if spontaneous labour or rupture of membranes occur.
Short-term complications
Bleeding and blood transfusions (4%), miscarriage (2%), premature delivery (30% of which three quarters of cases occurs in the later preterm perdiod at 32-36 weeks and one quarter below 32 weeks) .
Long-term complications
No long term complications are described in relation to this type of surgery. There is no need for postnatal surgery of the defect. Some long term complication can arise from consequences or rare extreme prematurity. Spina bifida is condition affecting motor function and continence all of which are improved by prenatal surgery and sometimes may require ventriculoperitoneal shunting to treat hydrocepalus.
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