Publication of results from the landmark Management of Myelomeningocele Study last year established fetal surgery as a viable option, and possibly the best option for ameliorating the complications of spina bifida.
But the Management of Myelomeningocele Study (MOMS) also appears to have had farther-reaching effects. In the 18 months since the trial results appeared (N. Engl. J. Med. 2011;364:993-1004), myelomeningocele (MMC) repair in fetuses repositioned from investigational surgery performed at just three U.S. centers to arguably standard of care that could potentially be done at whichever centers gear up to offer it. Beyond that, the possibility of effective and reasonably safe fetal MMC repair that the MOMS results documented is also proving to be a catalyst in the transformation of the still-young field of fetal surgery from an investigational, niche specialty to a more mainstream intervention.
"For many of the other [fetal surgery] interventions, there are so few cases that having more than a few centers doing them did not make sense. To have a fetal center you need a dedicated, multidisciplinary team available 24/7/365 that does a certain number of cases per year to keep up its team’s skills. For fetal surgery to be successful, it will need to be regionalized so that there is access for all patients, but also focused at centers of excellence so there is enough volume to keep skills sharp," said Dr. Mark P. Johnson, obstetrical director of the Center for Fetal Diagnosis and Treatment at the Children’s Hospital of Philadelphia (CHOP).
The MOMS result "has already had a profound effect on the treatment of MMC, on reimbursement standards for fetal intervention, and has defined how fetal surgery centers should be organized and staffed across the United States," wrote Dr. Shinjiro Hirose, a fetal surgeon at the University of California, San Francisco (UCSF), and his associates in an article on maternal-fetal surgery that appeared in June (Clin. Perinatology 2012;39:269-78).
Growing fetal-intervention options also put unprecedented responsibility on the physicians who provide primary obstetrical care to identify pregnancies early that may have an anomaly that’s amenable to surgical intervention and make an appropriate referral so that the disorder can be confirmed and intervention offered if it is possible.
Growing Numbers of MMC Repairs and Other Fetal Surgeries
Although the exact number of fetal MMC repairs done in the United States during the 18 months since publication of the MOMS results is hard to pin down, experts estimate roughly 80 surgeries occurred during April 2011-March 2012. They project as many as 100 or more being done in 2012, with about eight U.S. centers now offering the surgery, including the three centers that participated in MOMS and another five or so that have begun performing the procedure since the results were announced.
The other "high volume" fetal surgery now done is fetoscopic laser ablation of communicating vessels on the placental chorionic plate in monochorionic twin pregnancies that develop Twin-Twin transfusion syndrome (TTTS), which first became established as standard of care in 2004 (N. Engl. J. Med. 2004;351:136-44). It is now widely accepted as the preferred option in these cases, done on upward of 500 U.S. pregnancies a year. When the annualized rate of 600+ MMC repairs and laser ablations for TTTS couples with various low-volume fetal surgeries done for selected, rare anomalies, U.S. fetal surgery is on track this year to treat some 700-1,000 cases, and this number will likely rise substantially in the near future. The current, annual U.S. incidence of spina bifida in fetuses is about 2,500 (with about 1,500 infants born with MMC each year), suggesting that as fetal MMC repair becomes more widely accepted and performed, the number of U.S. surgeries for this indication could eventually run into several hundred a year.