Intensive in-hospital monitoring reduces premature delivery of monoamniotic twins, improves survival

Monoamniotic twins: An 8-year experience

With intensive and constant in-hospital fetal monitoring of monoamniotic (MA) twins, delivery can be delayed to beyond 34 weeks, and the live discharge rate can approach that of other twin pregnancies. This is significant because, historically, twins who shared a common amniotic sac had only about a 50 percent chance of both twins surviving. Those who did survive were typically delivered prematurely, resulting in a higher risk of severe health challenges and lengthy stays in neonatal intensive care units.

The findings, presented today at the American College of Obstetricians and Gynecologists’ 51st Annual Clinical Meeting, are part of a study of the past eight years’ experience of managing monoamniotic twins at Cedars-Sinai Medical Center in Los Angeles.

Monoamniotic twins are identical twins who share the same amniotic sac, instead of each twin having his or her own sac. This very rare condition occurs in an estimated 1 in 25,000 to 1 in 60,000 pregnancies, and historically has resulted in the in-utero death of one or both babies in 50 to 70 percent of cases.

According to Neil Silverman, M.D., Medical Director of Inpatient Obstetric Services at Cedars-Sinai and senior investigator on this project, the study was a retrospective case-controlled chart review of 40 women who delivered twins between January 1994 and December 2001. Ten of the mothers gave birth to monoamniotic twins, while the other 30 randomly selected women, who served as the control group, were the mothers of same-sex dichorionic diamniotic (DD) twins (twins who each had their own amniotic sac).

In the study, the two types of twins were found to have comparable rates of preterm labor, premature rupture of membranes, growth discordance, preeclampsia and gestational diabetes.

However, differences did exist between the two groups of twins. Not surprisingly, monoamniotic twins were admitted to the hospital at a significantly lower mean gestational age than the control twins (28 weeks vs. 37.5 weeks). The difference in gestational age at delivery for the two groups was more comparable: 33.5 weeks for the MA twins and 36.6 weeks for the DD twins.

While the MA twins had lower birthweights at delivery, there were no intrauterine deaths in either group, and only one neonatal death, which occurred in the control group. This neonatal survival and hospital discharge rate of 100 percent for monoamniotic twins was significantly higher than any previously reported survival rates for this very high-risk twin situation, in studies where fetal monitoring was conducted via frequent but intermittent surveillance.

Identical twins occur when a single fertilized egg splits into two embryos. In most cases, this split occurs sometime between days 3 and 8 after conception. At this point, the sacs are formed, and each twin has his or her own sac for developing throughout the pregnancy. However, if the split does not occur until after day eight, a single sac has already formed around both embryos, and they will share it throughout pregnancy. In this shared environment, it is common for their umbilical cords to become entangled, or for one twin to compress the cord of the other, resulting in death to one or both. Historically, the longer the twins remained in the womb, the greater the likelihood that this could occur.

“In the past, because of this fear of unpredictable prenatal death, we would empirically deliver these infants early – between 30-34 weeks,” says Kimberly Gregory, M.D., Director of the Division of Maternal-Fetal Medicine at Cedars-Sinai. “However, studies started to show that closer surveillance improved outcome. We learned in this study that with careful, continuous in-hospital monitoring, we could safely maintain the pregnancies longer to decrease the complications associated with prematurity and improve these babies’ prognoses.”

According to Dr. Gregory, this study is important because it shows that highly specialized inpatient management allows for continuous monitoring of both babies. This means that instead of making an arbitrary decision for early delivery, the delivery date can be determined based on demonstrated lung maturity with an amniocentesis, or earlier if the constant monitoring indicates that one of the babies is medically compromised. This means that often the babies can remain in the womb longer and attain a higher degree of maturity before delivery.

Dr. Gregory points out that this level of inpatient management needs to occur in a dedicated and highly specialized unit such as Cedars-Sinai’s Maternal Fetal Care Unit (MFCU). It was there that Lisa and Carolyn spent a combined 17 weeks before delivering monoamniotic twins a week apart last month.

Lisa, age 34 and a former CNN and EXTRA news reporter and producer, says she first learned that she would be delivering twins after undergoing an AFP test at 15 weeks gestation. Her doctor called to tell Lisa that she had found an abnormality in the test and wanted to perform an ultrasound right away. The ultrasound showed that there were twins, but it also showed that there was no separating membrane between them. Lisa was immediately referred to a perinatologist near her home in Northridge for a second opinion. He confirmed the diagnosis, suggesting that Lisa terminate the pregnancy and telling her that only about half of such pregnancies survive.

She was in disbelief. “I’d just spent the previous 45 minutes looking at two perfect babies on an in-depth ultrasound image,” she says. Unwilling to give up, she was referred to Dr. Silverman at Cedars-Sinai, who specializes in high-risk pregnancies. He confirmed the original diagnosis, but was much more optimistic, offering her hope and encouragement. “He cautioned us that this pregnancy would represent a huge commitment on our part,” Lisa remembers.

“He explained that once the babies reached a viable age – probably around 28 weeks – I would need to be admitted to the hospital for constant monitoring until the babies were born – hopefully not until at least 34 weeks. He also told us honestly that at any time before week 28, one or both of the twins could die if their cords became intertwined or if one of them compressed the cord of the other.” Once the twins reached the age of viability, and once Lisa was on constant monitoring, the babies’ odds of surviving with perfect health jumped to 80 percent, Dr. Silverman explained.

Those weeks up until the time of her hospital admission were extremely stressful, Lisa remembers. “Every minute of every day I was wondering if they were tangling themselves up, if they were moving, or if they were still alive. Once I was admitted to the hospital, that load of worry was lifted.”

Carolyn agrees. “It was very scary,” she says. “It was not until I was admitted to the hospital during week 27 that I could take a deep breath and not worry.”

In the Maternal Fetal Care Unit at Cedars-Sinai, both women were confined to their rooms – on six-foot leads which were attached to various monitors. “My weekly ‘outing’ was walking down the hall to get weighed,” Carolyn says with a chuckle.

“Believe it or not, it wasn’t that bad,” Lisa explains. The Maternal Fetal Care Unit rooms are designed for long-term patients. “I had a telephone and television, along with high-speed Internet access,” she says. “Plus, they let us decorate the rooms how we wanted to, so mine was like a little home, and I was actually able to do some work from the hospital. Friends came to visit and brought me special foods. It was fun.”

Carolyn, a genetics researcher at a Los Angeles hospital, also enjoyed the amenities during this time of necessary inactivity – using the time to read and to make revisions on a scientific manuscript she had submitted to the Journal of Virology. Her manuscript was accepted while she was in the hospital.

But the main point that both women emphasize is the unparalleled level of care they received on the MFCU – the bonds they established with their care teams. “The nurses, residents and physicians are all highly specialized,” says Carolyn. “It’s not easy to be confined, but they took great care of me and did everything they could to keep my spirits up. They kept me involved in the process and explained everything.”

“I can’t say enough to thank the nurses, residents and physicians on the MFCU,” says Lisa. “They made everything just great for me. They spent so much time with me explaining things, and they were so kind, so skilled. The bonds I formed with my ‘clinical partners’ there are truly special. Being confined really didn’t bother me because they were all great.”

Lisa, who also has a 6-year-old and a 3-year-old, gave birth to William Jude and Jonathan Gregory on March 18. Four days later she took her babies home – neither one with health problems of any kind.

Two days after Lisa went home, Carolyn’s twin daughters, Teri and Diana, were born. They went home from the Neonatal Intensive Care Unit on April 3, and both are in perfect health, their mother reports, with no need for special monitors.

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Cedars-Sinai is one of the largest nonprofit academic medical centers in the Western United States. For the fifth straight two-year period, it has been named Southern California’s gold standard in health care in an independent survey. Cedars-Sinai is internationally renowned for its diagnostic and treatment capabilities and its broad spectrum of programs and services, as well as breakthroughs in biomedical research and superlative medical education. Named one of the 100 “Most Wired” hospitals in health care in 2001, the Medical Center ranks among the top 10 non-university hospitals in the nation for its research activities.