In addition to learning that the size of their family would soon double, the Walnut Creek, Calif., couple's emotional roller coaster continued when they learned that their girls were at risk for twin-to-twin transfusion syndrome (TTTS), a complication that affects up to 15 percent of identical twin pregnancies.
Because they share a single placenta, the blood supplies of identical twin fetuses are connected so that they share blood circulation; although each fetus uses its side of the placenta, the blood vessels connecting the twins allow blood to pass from one twin to the other. With TTTS, blood can be transferred disproportionately, causing the "donor" twin to have decreased blood volume, slowing development and growth, as well as decreased urinary output, leading to a lower than normal level of amniotic fluid. Conversely, the blood volume of the "recipient" is increased, which can strain the fetus's heart and eventually lead to heart failure, and also higher-than-normal urinary output, which can lead to excess amniotic fluid.
Although Jennifer and Chris had known a couple that had lost twins because of TTTS, Jennifer admits, "We really didn't think that much about it." An exam three weeks later, however, would raise the specter of TTTS again. At this visit, Jennifer's East Bay obstetrician discovered that there was now a 20 percent difference in the size of the twins — a typical sign of TTTS. Jennifer was immediately referred to the UCSF Fetal Treatment Center and was seen less than 48 hours later.
At UCSF, Jennifer received an ultrasound, confirming the TTTS diagnosis. Dr. Hanmin Lee, fetal surgeon and director of the UCSF Fetal Treatment Center, informed the Canovas of their options, which included fetoscopic laser ablation. The UCSF Fetal Treatment Center is the only facility in the Bay Area — and one of only a few nationwide — to perform this procedure. Through laser ablation, there is an 80 percent chance of saving one fetus and a 50 percent chance of saving both. Severe TTTS without treatment has a mortality rate of 60 to 100 percent.
Faced with all the statistics, risks and possible outcomes, Jennifer and Chris chose laser ablation as the best choice to try and save both of their babies and checked into the medical center on Mother's Day. During the following morning's surgery, Lee inspected the twins' placenta with a very thin telescope called a fetoscope. The minimally invasive tool was placed into Jennifer's uterus through a tiny hole in the skin and identified the twins' connecting blood vessels. Using laser light from a small fiber along the tip of the fetoscope, Lee closed the connecting blood vessels and stopped the abnormal blood flow between the two fetuses. The surgery took approximately 45 minutes.
According to Jennifer, results were almost immediate. "After the ablation, they took more than one liter of amniotic fluid from one of the girls, and the other's fluid began to rise right away. I couldn't believe how quickly everything began returning to normal."
"Fetoscopic laser ablation illustrates one of the things that UCSF does best — developing and using new technology in a responsible way," says Lee. "We are at the forefront of using emerging technologies to offer hope where there once was none."
Less than three months after the procedure, hope became reality when Jennifer gave birth to Julia and Samantha, two perfectly healthy girls. In fact, Samantha, who was the smaller "donor" twin in utero, was born a full ounce heavier than her sister.
"We couldn't be happier with the level of care we received," says Jennifer. "Seeing Julia and Samantha today, you would never know that anything was ever wrong."
Story written in April 2008.
Fetal Treatment Center
400 Parnassus Ave., A123
San Francisco, CA 94143
Phone: (415) 476-0445
Fax: (415) 502-0660