MONTREAL -- As prenatal diagnostic techniques become increasingly sophisticated, options for fetoscopic as well as open fetal surgery are rapidly evolving as well, Dr. Timothy Crombleholme said at the annual meeting of the Society for obstetric Anesthesia and Perinatology.
"We see a whole range of fetal problems, from choroid plexus cysts, to agenesis of the corpus callosum, complicated CNS problems, sacrococcygeal teratoma, obstructive uropathy, and even myelomeningocele, which is somewhat controversial because for the first time we're [attempting to treat] a nonlethal condition," said Dr. Crombleholme of the Center for Fetal Diagnosis and Treatment at Children's Hospital of Philadelphia and the University of Pennsylvania, Philadelphia.
Simply knowing the range of options for these conditions is a valuable lesson for obstetricians and can have a profound effect on their patients.
"Maybe 10% of the patients we see actually need to have a procedure done in utero, but the vast majority of conditions can be managed postnatally. Often, we will do a complete evaluation and then send the women back to her referring doctor who we will then work closely with for the rest of the pregnancy," Dr. Crombleholme explained.
Among the most exciting procedures performed at the center is the in utero treatment of congenital diaphragmatic hernia (CDH), he said.
It has been known for years that in animal models, fetal tracheal occlusion can promote lung growth, increase alveolar surface area and number, and reduce visceral involvement in the chest, Dr. Crombleholme said. His center currently treats isolated CDH in fetuses before 26 weeks' gestation with the placement of a clip across the fetal trachea.
The fetal neck and chest are exposed through a small hysterotomy, after which an incision is made just cephalad to the sternal notch to expose the trachea, he explained.
The trachea is then meticulously dissected to avoid injury to the laryngeal nerves, the clip is placed across the fetal trachea, and both fetal and maternal incisions are then closed.
Once the immediate postoperative concerns about premature labor, inadequacy of amniotic fluid, and extraamniotic clotting are dealt with, weekly ultrasounds should show steady lung growth.
This growth should be monitored because it can lead to cardiac compromise and fetal hydrops requiring early delivery. In the absence of such complications, a planned EXIT (ex-utero intraparturm treatment) procedure and clip removal can be performed near term.
One of the most common conditions treated at the center is congenital cystic adenomatoid malformation (CCAM), a multi-cystic mass of pulmonary tissue with proliferation to the bronchial structures that is usually restricted to one lobe of the lung.
During the procedure, the fetal arm and chest are exposed via hysterotomy, with the rest of the body remaining in the amniotic sac. The mass is then exteriorized and any systemic feeding vessels are ligated before dissection of the cyst with electrocautery.
Daily ultrasounds for the first 2 weeks should confirm the resolution of placentomegaly and fetal hydrops, after which weekly ultrasounds should confirm compensatory fetal lung growth, he said.
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