Ex utero intrapartum Tx offers ailing fetuses a second chance

OB/GYN News, May 15, 2002 by Erik L. Goldman

BOSTON -- Advances in intrauterine surgery, specifically the development of ex utero intrapartum treatment, have made it possible to save many fetuses that stood almost no chance of survival a few years ago, Dr. Russell Jennings said at an ultrasound meeting sponsored by Harvard Medical School and Brigham and Women's Hospital.

"If we can do only one thing to save lives, it would be to convince parents not to terminate a pregnancy until they speak to someone who knows what is possible now," said Dr. Jennings, director of the Advanced Fetal Care Center, Children's Hospital, Boston.

Dr. Peter Doubilet of the department of radiology at Brigham and Women's agreed. While fetal surgery is far too specialized and expensive to be widely practiced, it is essential for the clinical community to know what pioneers such as Dr. Jennings and his team are now doing, he said.

"We need wider awareness, so the cases will be funneled into the centers of expertise," Dr. Doubilet said at the meeting.

Ex utero intrapartum treatment (EXIT) involves an induced partial delivery of the fetus to bring the head, neck, and thorax out of the birth canal, while leaving the umbilical-placental connection intact so that the baby is perfused from the placental source. The fetus can be immediately placed on extracorporeal circulation membrane oxygenation (ECMO) if necessary, and the surgical team can go to work while the fetus remains connected to the placenta.

EXITs can be done as early as week 23 of gestation and are indicated in situations when a fetus is already well developed, but a correctable anormaly is likely to compromise survival. These include any anomaly that carries a high risk of hypoxia, tracheal or laryngeal atresias, large neck masses, congenital cystic adenomatoid malformations, and diaphragmatic hernias.

These procedures are the quintessence of medical teamwork. At Dr. Jennings's center, the operating room begins to look like a football field, with the fetal team working at one end of the table, while a separate maternal team cares for the mother. There can be as many as 13 people in the room at one time. These operations require coordination between fetal surgeons, anesthesiologists, sonologists, obstetricians, nurses, and support staff.

"Whenever we are reaching the fetus, we are putting the mom at risk. We have to admit that up front. Therefore, anything we do to the fetus must have significant benefits," Dr. Jennings said.

When these interventions are appropriate, the outcomes can be profound. He described the case of a fetus with a massive pharyngeal tumor that completely obstructed the trachea and created massive distortions of the face and oropharynx. By doing the EXIT and putting the child on ECMO, the Children's Hospital team was able to remove the tumor and correct the child's head and neck, ensuring survival and a completely normal appearance.

The EXIT to ECMO procedure has also been used in cases where a congenital cystic adenomatoid malformation threatened to compromise lung development and function through mechanical occupation of the thoracic space.

"None of the percutaneous intrauterine procedures will work in these cases. You've got to get the kid out and operate to remove the mass in order to make a difference," Dr. Jennings said.

In these cases the Children's Hospital group will opt for EXIT, followed by intubation and ventilation. This often brings the fetal oxygen saturation above 90%. If the lungs are functioning, the surgeons can then go in and remove the adenomatoid mass. If the lungs cannot work due to the mass, the child is placed on ECMO, the mass is then removed to allow the lungs to function, and ECMO is stopped.

The EXIT to ECMO maneuver has also proved useful in severe cases of diaphragmatic hernia. "These kids don't die from pulmonary hypoplasia as most people think. They die from hypoxia, barotrauma, or pulmonary hypertension. By using EXIT to ECMO, the Children's Hospital team can avert the development of hypoxia and barotrauma. "We're getting 95% survival, up from 65% in 1999," he said.

Their most recent triumph was the treatment of hypoplastic left heart syndrome, a condition in which fetal cardiac development is severely compromised due to a stenosis of the aortic valve. If a child with the condition survives at all, he or she will likely have neurologic and cognitive deficits owing to poor cerebral circulation. Many of these children need heart transplants by the time they are teenagers.

Dr. Jennings said there is "a little window" during fetal development--typically after the 20th week--where it is possible to dilate the aortic valve, allowing the left ventricle to contract properly, thus restoring a relatively normal ejection fraction. Interventional cardiologists working with the fetal surgery team have now done two such cases.

Once ejection fraction was restored to normal ranges, these infants developed normally.