Most medical decisions come down to weighing risks and benefits, and trying to ensure that the balance falls to the good.

About 18 months ago, the diminutive medical and surgical niche that’s fetal surgery (fewer than 1,000 U.S. fetal surgical procedures are done annually) came out with the blockbuster finding that fetal surgery to repair myelomeningoceles and blunt the complications of spina bifida was relatively safe and produced substantial benefits, compared with more conventional treatments that affected infants and children undergo when treatment starts after birth.

"Views of a Foetus in the Womb" (c. 1510 - 1512) is a drawing by Leonardo da Vinci.

To help ensure an adequate number of cases in MOMS (Management of Myelomeningocele Study) to produce a meaningful result in a reasonable amount of time, the couple of dozen or so U.S. medical centers that offer fetal surgery agreed to limit fetal-myelomeningocele repair to three U.S. locations: the Children’s Hospital of Philadelphia (CHOP); Monroe Carell Jr. Children’s Hospital at Vanderbilt University in Nashville, Tenn.; and the University of California, San Francisco (UCSF). Even when all U.S. cases were funneled into these three sites during 8 years, the study enrolled all of 183 cases. The landmark 2011 report on outcomes in MOMS 1 year following birth had data on the first 158 cases (78 fetuses that underwent in utero myelomeningocele repair and 80 control pregnancies for which interventions occurred after birth).

The fetal-myelomeningocele repair world quickly began to change once the New England Journal paper came out in March 2011. The surgery was no longer investigational, and other U.S. centers could get into the act, if they wanted, and if they dared.

During the nearly 18 months since then, about five new programs jumped into the myelomeningocele-repair pool. That number is a little uncertain because no one keeps "official" tabs on who does the surgery, nor is there any official tally of how many fetal repairs are done, or their results. What is clear is that in the 18 months since the MOMS report, roughly 100 fetal myelomeningocele repairs were done in the United States, more than during 8 years of MOMS from February 2003 through the end of 2010.

And, at least as of now, no information is on record for how those 100 or so most recent cases have fared, including the outcomes from the new programs. That’s largely because it takes at least a year following delivery of a repaired fetus to have outcome results with follow-up similar to MOMS, and if you do the math, that means the outcomes from even the first post-MOMS cases are just now trickling in.

The risk-benefit balance at work here is this: Can new centers offer fetal myelomeningocele repairs – an understandably challenging technical undertaking – to boost access to mothers and their affected fetuses, while at the same time ensuring that their outcomes are at least as good as what happened in MOMS? It’s a question that’s not yet been answered.

It’s also a question that so troubled officials at the Eunice Kennedy Shriver National Institute of Child Health and Human Development – the U.S. agency that funded MOMS – that soon after the MOMS result came out, the institute took the unusual step of organizing a panel of experts to come up with guidelines on what a program should have in place if it wanted to venture into the fetal-myelomeningocele repair business. Those recommendations are still in process and are expected out before the end of this year. A preview was offered in June by some UCSF clinicians, but I’ve been told that their summary of the pending guidelines is not completely up to date.

The wider-access issue is very real. I spoke about it with Dr. Foong-Yen Lim, surgical director of the fetal care center at Cincinnati Children’s Hospital, one of the newbie programs that began offering this fetal surgery post MOMS, and that as of mid-August had done 10 cases. Having fetal-myelomeningocele repair available at more U.S. sites is important because during MOMS, when only three sites were available, he knew of cases in which the parents of affected fetuses opted not to go out of town for fetal repair because they could not afford it or could not deal with the relocation. Of course, some patients also might have not wanted to commit to being part a study knowing that once in, they had a 50-50 chance of randomization to standard care.

Dr. Lim told me how deeply he felt the responsibility he and his associates took on when they decided to start offering fetal-myelomeningocele repair and thereby boost access for affected families in the Cincinnati area. "People who take on this procedure need to ask themselves ‘Are we doing as good a job as the other places?’ " he said. He also told me that Cincinnati Children’s counselors make it clear to prospective families that if they prefer, they could travel to CHOP, Vanderbilt, or UCSF, the U.S. sites with the most experience and best-documented track records.

It’s all a balance of risk and benefit.

–Mitchel L. Zoler (on Twitter @mitchelzoler)

Fetal Spina Bifida Surgery: Balancing Access and Outcomes