Cedars-Sinai Medical Center's Prenatal Program Pushes the Frontiers of Diagnosis From the Second Trimester Into the First

March 16, 1999

LOS ANGELES (March 16, 1999) - With three-dimensional ultrasound, genetic testing procedures that can now be done in the first trimester of pregnancy, and a medical staff that is nationally recognized for its size and leadership in research, the prenatal diagnostics program at Cedars-Sinai Medical Center gives women access to the very latest techniques at the very earliest opportunity.

"We offer comprehensive services that extend from pre-pregnancy counseling through the entire pregnancy," said Lawrence D. Platt, M.D., chairman of the Department of Obstetrics and Gynecology, and chairman and director of the department's residency program. "We have a very strong interest in first trimester fetal diagnosis, moving the frontiers from the second to the first trimester. In fact, with our advances in ultrasound and our expertise in biochemical testing, we're now able to perform tests in the first trimester that previously had to wait until the second or even the third."

With the recruitment late last year of a new co-director of the department's division of reproductive genetics, Cedars-Sinai's program is clearly the largest first-trimester diagnostic center on the West Coast, offering a medical team that includes three physicians board-certified in obstetrics and gynecology, maternal-fetal medicine, and genetics. According to Dr. Platt, few if any other centers in the nation maintain this depth of expertise.

John Williams III, M.D., who has been a member of the Cedars-Sinai medical staff since 1982 and was a full-time faculty member until 1988, became co-director of Reproductive Genetics in November 1998. He joins Dru E. Carlson, M.D., who has served as director of the division since 1990. Like Dr. Carlson, Dr. Williams is certified in obstetrics and gynecology, maternal-fetal medicine (a subspecialty of obstetrics and gynecology), and medical genetics. Dr. Williams is also board certified in clinical cytogenetics, a subspecialty of medical genetics for chromosome analysis. This certification, earned in 1990, enabled him to direct his own laboratory while in private practice for 10 years before returning to the Cedars-Sinai faculty.

In their efforts to detect and diagnose potential genetic defects, physicians use a variety of techniques, depending on such factors as the age of the woman and the family's medical history. Typically, a woman who will be under age 35 at the time of delivery is offered a screening blood test that estimates the risk of the fetus having certain defects, including spina bifida, Down syndrome and other chromosomal abnormalities or structural defects. Depending on the results of this screening, the woman chooses whether or not to follow up with a diagnostic test. On the other hand, because certain birth defects are more common in the pregnancies of older women, a woman who will be 35 or older at the time of delivery (and anyone who has a family history of genetic defects) is encouraged to take advantage of diagnostic tests -- either amniocentesis or chorionic villus sampling.

While these two tests have a common goal -- the collection of fetal cells so that their chromosomes can be analyzed for defects -- they differ in terms of timing, the location from which fetal cells are withdrawn, and often the approach itself.

Amniocentesis has traditionally been performed at 15 to 18 weeks gestation. The physician inserts a thin needle through the abdomen, into the uterus and into the amniotic sac. A small amount of fluid -- which contains discarded cells from the developing fetus -- is withdrawn. The cells are later cultured and examined microscopically.

CVS can be done as early as 10 to 12 weeks gestation. Instead of removing amniotic fluid, however, the doctor takes a small sample from the mat of chorionic villi, or finger-like projections on the fetal side of the chorion frondosum, which is the placenta before it is technically called the placenta. Chorionic villi may be removed transabdominally, in much the same way amniocentesis is done. This also can be performed transcervically. The physician guides a small catheter through the cervix and into the chorionic villi. In either approach, as in amniocentesis, ultrasound imaging is used to direct the needle or catheter and ensure the safety of the fetus.

Cedars-Sinai's prenatal program is currently participating in a multi-center study funded by the National Institutes of Health that is comparing transabdominal CVS with early amniocentesis, which is defined as that performed before 15 complete weeks of gestation.

"There have been a number of reports suggesting that early amniocentesis is safer than chorionic villus sampling, but there have been no controlled studies to back that up," said Dr. Williams. "This study compares early amniocentesis with transabdominal CVS, both done at about the same time, 13 to 14 weeks."

In fact, said Dr. Williams, many people mistakenly believe CVS carries a greater risk than amniocentesis in general. These misconceptions come about, he said, because most miscarriages occur at an earlier gestational age.

"What happens is that the majority of women who were destined to miscarry have already done so by the time they get to 16 or 17 weeks. There is a higher baseline risk for miscarriage at 10 and 11 weeks, which is around the time we're doing CVS," said Dr. Williams. "If we subtract the baseline risk for having a miscarriage from the observed loss rate at the time of the procedure -- for both CVS and amniocentesis -- the difference is not statistically significant. In fact, as more women understand the true risks and benefits of CVS, many more will probably choose CVS over amnio."

Carrie Yoshida, a resident of Redondo Beach, had never heard of CVS until she was referred to Cedars-Sinai by her gynecologist. Pregnant for the first time at age 41, she was concerned about her baby's health not only because of her age but because she had been born with "webbed" fingers on her left hand -- some of the digits and knuckles were missing -- and she wanted to be sure this was not a genetic disorder likely to be passed on.

Yoshida and her husband were first interviewed by genetics counselors at Cedars-Sinai, her hand was examined by Dr. Williams and a CVS was performed. She said her mind was eased when she learned that the problem with her hand most likely is not of genetic origin, and the results of the CVS indicated that the baby does not appear to be at high risk for birth defects. A subsequent high-resolution ultrasound showed what appears to be a perfectly healthy baby boy, due around the first of August.

She said the only discomfort she felt during the CVS was a sense of pressure against her bladder. "My husband came with me but he didn't even need to hold my hand," she said.

One of the benefits of CVS is the turnaround time on test results. "Once a woman has been told that she is at increased risk, she may tend to distance herself emotionally from the pregnancy until she gets the results," said Dr. Williams. "If the patient has an amniocentesis at 16 weeks, she will not be getting the results until about 18 weeks into the pregnancy. That's when, if it's good news, she'll begin to bond with that baby. But if the patient has CVS at 10 weeks, we can get preliminary results within a couple of working days. She gets her good news at 10 1/2 weeks, and that's when she bonds."

"The mother can also maintain her privacy more easily because most women are not obviously pregnant in the first trimester," said Dr. Williams. "Only those individuals who have a need to know would know that she's pregnant. Co-workers and distant relatives don't need to be aware of the pregnancy until after she has gotten her results."

Karen Mohr of Hermosa Beach chose CVS in part because she and her husband wanted to get the results quickly. The mother of two children, ages 8 and 10, Mohr is over age 35.

Getting the results within a couple of days, early in the pregnancy, greatly relieved her mind, and the procedure itself was easier than anticipated. "Everything went great. They had prepared me for it to be uncomfortable but it was nowhere near what they had described. It was more comfortable than having a Pap smear," said Mohr. The baby is due in August.

Despite having two previous miscarriages, she said she felt confident going into the procedure because of Dr. Williams' expertise. While amniocentesis is performed in medical centers and practices throughout the community, few sites specialize in CVS. The procedure has been available at Cedars since 1985 and Drs. Platt, Carlson and Williams all have extensive experience. Dr. Williams, for example, has performed about 9,000 CVS procedures to date.

Earlier screening and testing procedures are beneficial even when the results are not good news because they allow women to assess their options, protect their health, and get the support they need to deal with the emotional aspects of the situation.

"Not all women will terminate the pregnancy when faced with an abnormal diagnosis, but for those who do, the risks of terminating are about five-fold greater after 15 weeks versus before 15 weeks," said Dr. Williams. "Also, the complications that tend to occur are more severe in the later terminations than in the earlier terminations. By offering an earlier test, we can decrease the risk to the mother."

All genetics counselors in the program are board-certified, specifically trained to provide the best information and support. For patients who give birth to babies with abnormalities, the medical center also offers pediatric geneticists for follow-up.

In addition to its involvement in the study comparing early amniocentesis to CVS, Cedars-Sinai's prenatal program is the Los Angeles area's training site for an NIH-funded study looking at a noninvasive Down syndrome screening program based on maternal age, maternal biochemical markers measured from blood obtained by a finger stick, and a fetal ultrasound measurement.

Down syndrome, the result of a genetic defect that creates an extra copy of chromosome 21, is the most common chromosome anomaly, comprising about 50 percent of all chromosomally abnormal babies. The levels of two particular proteins in the blood of pregnant women have been found to be an indicator of risk for Down syndrome. If free beta human chorionic gonadotropin (hCG) is present in high concentrations, and pregnancy associated plasma protein A (PAPP-A) is low, the baby is considered to be at high risk. It also has been found that fetuses with Down syndrome and other abnormalities tend to have an excess of skin at the back of the neck (nuchal translucency), which can now be visualized by ultrasonography in the first trimester.

According to estimates, screening by maternal age and nuchal translucency now identifies more than 80 percent of fetuses with Down syndrome. When the maternal blood protein markers are taken into account, the detection rate may be as high as 90 percent. The current study was conceived to more precisely determine the value of combining blood protein measurements and nuchal translucency to determine the risk for genetic abnormalities. These non-invasive screenings enable physicians to make early recommendations for more invasive tests when appropriate.

One of the keys to these screenings is the quality of the ultrasound imaging. Under the direction of Dr. Platt, one of the most respected authorities on ultrasonography and president-elect of the American Institute of Ultrasound in Medicine, Cedars-Sinai's center offers the latest in both standard and 3-D ultrasound equipment. In fact, Dr. Platt and his associates work with manufacturers to research and develop the latest generations of equipment.

"We have the highest resolution systems available and they we have allowed us to make the earliest possible diagnoses," said Dr. Platt, who is board-certified in obstetrics and gynecology and in maternal-fetal medicine. The latest 3-D ultrasound system has been in place at Cedars-Sinai for more than a year. In studies, three dimensional images have not only been used to confirm suspected diagnoses, but in some instances to change a diagnosis because physicians were better able to visualize the fetus.

In addition to the work being done at Cedars-Sinai to make early screening and testing available to patients, the prenatal diagnostic center is the area coordinator for California's Expanded AFP program, which makes the alpha-fetoprotein (AFP) blood test available to high-risk patients in the second trimester. Unlike the first trimester blood test and ultrasound used in screening for the risk of Down syndrome, the AFP test can predict the presence of fetal neural tube defects, such as spina bifida.

To arrange an interview, please call 1-800-396-1002 (Thanks for not publishing this number in stories.)

Cedars-Sinai Medical Center

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