Laser Ablation for Complicated Twin-to-Twin Transfusion Syndrome

How do you perform a minimally invasive fetoscopic laser ablation for TTTS when the placenta covers the entire anterior uterine wall?

The presentation was textbook twin-twin transfusion syndrome: one recipient twin floating in a glut of amniotic fluid, the other “stuck” in its amniotic sac with essentially none, indicative of the discrepancies of placental blood flow — potentially fatal for both twins — that characterize the condition.

The ideal situation for TTTS laser ablation

The best solution to TTTS is typically fetoscopic laser photocoagulation, in which a surgeon makes a 3-millimeter incision and, with a fetoscope inserted into the uterus and through the amniotic sac, uses a laser to cauterize and seal off vascular connections in the placenta.

“The ideal situation would be to visualize the placenta with the fetoscope at a 90-degree angle,” says maternal-fetal medicine specialist Nick Behrendt, MD, one of four fetal surgeons at the Colorado Fetal Care Center at Children’s Hospital Colorado. “You basically want to be perpendicular to the placenta.”

That’s pretty manageable for placentas that implant on the posterior wall of the uterus. The surgeon just goes in through the anterior wall. It’s a bit tougher with an anterior placenta, but the surgeon can usually manage with some creative positioning on the mother’s part.

When the placenta covers the entire anterior uterine wall and then some, though, that’s a challenge.

An innovative approach to a unique case of TTTS

“This case is really unique,” says Dr. Behrendt. “We just couldn’t find a safe entry spot using what I would say are our traditional methods. This is one of the only times we’ve seen that.

“We had to put our heads together,” he adds.

The team came up with a plan that called for Dr. Behrendt and all three other fetal surgeons — Henry Galan, MD; Kenneth Liechty, MD; and Michael Zaretsky, MD — in the operating room. Typically only two would scrub in.

They settled on a technique adopted from myelomeningocele repair, an open fetal procedure. They started by opening the patient’s abdomen with a transverse incision and then opened the fascia vertically.

“Flipping” the uterus

From that access point, they flipped the posterior uterus forward, outside of the maternal abdomen, using a c-section tool called an Alexis O retractor. Drs. Zaretsky and Liechty held the uterus while Dr. Galan used ultrasound to help guide Dr. Behrendt, who had to perform the ablation visualizing in reverse.

“We basically had to turn our brains upside down, since we were entering through the back of the uterus. Once we were able to do that, we had to reorient ourselves, almost like we were treating a posterior placenta,” he says. “Technique-wise, though, it went great, because we were able to get that perpendicular access that we would have otherwise never been able to get for this patient.”

When it was done, they sutured the access port shut, placed the uterus back in the patient’s abdomen and closed the layers they started with.

Follow-up and delivery

The mother, who traveled from a small town in Nebraska to get the procedure, had been referred by Dan Connealy, MD, a maternal fetal medicine specialist in Omaha, and the team worked closely with him to develop a modified follow-up care plan that would keep her closer to home for the rest of her pregnancy. She carried the twins another 13 weeks and 6 days to deliver at 35 weeks — about three weeks longer than the average for twins with TTTS who get laser treatment.

“Every case of TTTS has some uniqueness to it,” says Dr. Behrendt. “This was just another one of those things ⎯ but being able to think through it together, and having the practice and expertise to do both open and minimally invasive procedures, allowed us to modify a technique we use for a totally different procedure, and I think we did it well.”