NEW TEST MORE ACCURATE AT DIAGNOSING PRETERM LABOR
COLUMBUS, Ohio -- A simple, in-hospital biochemical test is a better predictor of whether a woman will go into labor prematurely than either her uterine contractions or cervical dilation, new research suggests.
The test, which is performed like a Pap smear, indicates the presence of a substance called fetal fibronectin -- a glue-like compound that connects the amniotic sac to the inner wall of the uterus during pregnancy. The test was approved by the Food and Drug Administration (FDA) in October.
"This test predicts much better than anything we have now who is likely to develop preterm labor and who isn't," said Jay D. Iams, professor of obstetrics and gynecology at Ohio State University and lead author of the study. "Ordinarily, fetal fibronectin doesn't leak out into the birth canal. When it does, it tells you that there's been a disturbance between the uterus and the amniotic sac and that the risk of early labor is there."
The lack of a valid, reliable tool to help diagnose early labor has long plagued obstetricians, Iams said.
"Preterm labor has been -- and continues to be -- both over-diagnosed and under-diagnosed," he said. Studies show that about 40 percent of women diagnosed as being in early labor are not actually in labor. However, studies also show that obstetricians miss the opportunity to diagnose premature labor early in about 15 to 20 percent of cases.
"The fetal fibronectin test helps with both problems," Iams said. "It's particularly good at eliminating the false diagnoses, but it's also a good tool for making sure we don't miss people."
Iams conducted this research with James A. McGregor, professor of obstetrics and gynecology at University of Colorado Health Science Center; T. Murphy Goodwin, an assistant professor of obstetrics and gynecology at the University of Southern California; Richard Lowensohn, professor of obstetrics and gynecology at Oregon Health Sciences University; Gillian Lockitch, professor of pathology at the University of British Columbia; David Casal, a scientist with Adeza Biomedical; and Usha Seshadri Kreaden, also with Adeza. The group's work was published in a recent issue of the American Journal of Obstetrics and Gynecology. For their study, the researchers examined regnant women with symptoms of preterm labor at five university medical centers (Ohio State University, University of Colorado, University of Southern California, Oregon Health Sciences University and University of British Columbia). The women were all between their 24th and 34th week of pregnancy; all had cervical dilation of less than three centimeters. The researchers used a cervical swab to test each woman for the presence of fetal fibronectin. In addition, they recorded each woman's cervical dilation and contraction frequency during the interval before delivery.
"These numbers tell us that the test predicts especially well who isn't going to deliver this week, who doesn't have a problem at all," Iams said.
Iams said the fetal fibronectin test may someday be used as an early pregnancy screening tool to identify those women at risk of giving birth too soon.
"The test does predict an increased chance of premature delivery," he said. "Right now, however, the problem with the test being used as a screening tool is that we don't know what to do with a positive reading. We're not sure how to treat a woman who has a positive fibronectin test, but no apparent symptoms of early labor."
Ohio State and the other medical centers involved in the study are addressing that question with current research, Iams said.
For now, however, Iams believes the fetal fibronectin test will reduce health care costs -- and human suffering -- by preventing both premature births and unnecessary treatment of preterm labor.
"A baby born prematurely typically costs about $100,000 -- and that's just the hospital care," he said. "That doesn't take into account the long-term consequences -- increased risk of cerebral palsy, blindness, deafness, chronic lung disease. With the fetal fibronectin test available, the potential for both saving money and saving babies from this fate is tremendous. On the other side of the coin, the problem of women being over-diagnosed as being in early labor is a huge one. If we can prevent some of those cases, the savings will be great.
Iams' research was funded, in part, by Adeza Biomedical, the manufacturer of the fetal fibronectin test. The findings reported in the American Journal of Obstetrics and Gynecology were also presented to the FDA as part of the test's approval process.
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Contact: Jay D. Iams, (614) 293-8736
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