Chapter 27: FETAL THERAPY: MATERNAL FETAL SURGERY AND PERCUTANEOUS ULTRASOUND GUIDED FETAL THERAPY TECHNIQUES FOR CONGENITAL ANOMALIES

Definitions

1. Bipolar cord cautery: a percutaneous ultrasound-guided technique with endoscopic evaluation capability that introduces a 3.0-mm bipolar cautery device through a 4.0-mm trocar sheath, and with ultrasound guidance, the umbilical cord is grasped between the bipolar device's "jaws" and 60 to 100 W of power is applied in 2 to 3 sites to obtain cord/vascular occlusion with absence of umbilical cord blood flow documented by Doppler evaluation; endoscopic visualization of the cord cautery sites can be undertaken as well, but complete occlusion can not be confirmed visually.

2. Congenital anomalies/birth defect terminology:

   1. Deformation: a mechanical force that interferes with a normally developing process causing a shape/positioning abnormality of a fetal organ or body part (pulmonary hypoplasia secondary to congenital diaphragmatic hernia or pleural effusions, or congenital adenomatoid malformations or early onset prolonged oligohydramnios).

   2. Disruption: a teratogenic event or destructive insult (vascular, infectious, metabolic, drug) that interferes with a normally developing process causing an abnormal structural/developmental outcome of a fetal organ or body part (recipient cardiac pathology in twin-to-twin transfusion syndrome, cerebral ventriculomegaly secondary to viral or germinal matrix hemorrhage with neuronal loss).

   3. Dysplasia/aplasia/hypoplasia: pathologic disorganization of the cell structure itself or disorganized cells within the tissue or tissues within a particular structure to create a structural anomaly; absence of a tissue or an organ due to absent cellular proliferation; insufficient cellular proliferation leading to undergrowth (renal dysplasia, renal agenesis, renal hypoplasia).

   4. Malformation: primary structural/developmental disorganization of a fetal organ or body part (congenital heart disease, myelomeningocele, sacrococcygeal teratoma, urethral obstruction) usually prior to embryonic week 8.

3. Endoscopic laser coagulation: following initial ultrasound evaluation with placental/umbilical cord insertion "mapping," this percutaneous ultrasound-guided technique introduces a 2.0-mm fiberoptic endoscope into the uterine cavity under local anesthesia or with conscious maternal sedation to examine and identify placental surface vascular anastomoses between monochorionic twins with twin-to-twin transfusion syndrome; anastomoses are then selectively interrupted by laser coagulation creating a "surgical" dichorionic placenta.

4. EXIT delivery: ex utero intrapartum treatment (EXIT) was initially designed for reversal of tracheal occlusion performed in fetuses with severe diaphragmatic hernias; this delivery strategy ensures an optimal controlled environment with the fetus on uteroplacental bypass allowing fetal surgery of the neck and thorax for 50 to 70 minutes.

5. Maternal–fetal surgery: fetal therapy that requires maternal laparotomy and hysterotomy to obtain access to the fetus with resulting increased maternal and fetal risk.

6. Radiofrequency ablation: a percutaneous ultrasound-guided technique that allows the 2- to 3-mm radiofrequency device to be placed at the correct vascular/tissue location to then create increased temperature changes by high-frequency alternating current between the electrodes in the vascular/tissue location causing coagulation, tissue desiccation, and vascular occlusion as assessed by Doppler evaluation.

7. Thoracoamniotic shunt: a unidirectional fluid flow "pigtailed" shunt, which is inserted with one end in the fluid-filled chest location and the other end in the amniotic fluid space placed under percutaneous ultrasound guidance; this allows the drainage of the chest fluid into ...