Thursday, October 9, 2003

Down syndrome tests show promise


Combo finds defect better, sooner

By Linda A. Johnson
The Associated Press

A new combination of blood tests and ultrasound can detect fetuses with Down syndrome sooner and more accurately than standard U.S. screening tests, offering parents-to-be more peace of mind and more time to decide whether to end a pregnancy, researchers say.

The study of 8,216 women at a dozen U.S. medical centers confirms findings in England and elsewhere, where the combination is already widely used.

"It's earlier by about a month, so we've moved the standard testing to the first trimester and improved its accuracy," said lead researcher Dr. Ronald Wapner, chairman of obstetrics and gynecology at Drexel University College of Medicine in Philadelphia. "The absolute biggest advantage is this allows women to make private decisions" before they are visibly pregnant.

The usual blood screenings done in this country identify up to 75 percent of Down syndrome babies, but do not yield results until about 20 weeks into pregnancy, when abortion is more dangerous for women and often difficult to obtain.

The new combination - two blood tests, ultrasound and the mother's age - correctly identified 85 percent of fetuses with Down syndrome and yielded results at about 12 weeks.

Nine percent of the time, it incorrectly indicated a fetus probably had Down syndrome.

When the four indicators together show a high probability of Down syndrome, women can choose a definitive - and invasive - test. In chorionic villus sampling, cells are withdrawn from the placenta with a needle, usually at 10 to 12 weeks of pregnancy. In amniocentesis, which is more commonly done in this country, fluid is drawn from the amniotic sac with a needle; it is done at 14 weeks or later. Both techniques carry about a 1 percent risk of miscarriage.

The study was reported in today's New England Journal of Medicine.

Dr. Mark Evans, director of the Institute for Genetics and Fetal Medicine at St. Luke's's/Roosevelt Hospital Center in New York, said the study will cause a gradual shift from second-trimester screening to this method.

"There have been literally hundreds of thousands of patients evaluated worldwide who confirm these data," said Evans, president of the Fetal Medicine Foundation of America.

But in an accompanying editorial, Drs. Michael Mennuti and Deborah Driscoll of the University of Pennsylvania School of Medicine wrote that second-trimester screening should continue to be the standard until detailed guidelines can be developed for using the ultrasound and other tests.

Because women 35 or older have a higher risk of having a Down syndrome baby - one chance in 270 - most get one of the invasive tests.

In addition to looking at the mother's age, the screening combination tested by Wapner and colleagues looks for low levels of a protein called pregnancy-associated plasma protein A, and for high levels of a type of the hormone human chorionic gonadotropin. The ultrasound test looks for telltale high levels of fluid in the fetus' neck.

Evans, who has researched the ultrasound test and been using it for a decade, said it is the single best marker of Down syndrome. But he also warned that correctly reading the ultrasound requires specialized training and experience. It is available at some U.S. academic medical centers.

Wapner said doctors might cut in half the number of invasive tests by using the combined screening to correctly identify normal as well as Down syndrome fetuses.

The new combination of blood tests and ultrasound also proved highly effective at detecting the second most common of the severe chromosome abnormalities that do not usually kill the fetus, a condition known as trisomy 18.




TOP STORIES
Ohio tuition program on hold
Miami U. service workers end strike
Blue Ash may require helmets
Firefighters hold memorial march

IN THE TRISTATE
I-75: No easy fix to woes
Bomb victim, 10, here for treatment
Delhi infantryman remembered as a hero
Council hopefuls fail to inspire
Thrifty solution way too costly
Art museum extends invitation to Colerain
Ex-priest awaits decision
Down syndrome tests show promise
Pet a pig, try kettle corn at Blue Ash fest
Juror mouths off, officers get off in Lawrenceburg
Ruling based on religion tossed
Mayor urges city action to get cop report released
Records request argued
Regional Report

ENQUIRER COLUMNISTS
Pulfer: At NKU, it's really not about the buildings at all
Howard: Good Things Happening

BUTLER, WARREN, CLERMONT
Evidence re-checked in slaying
Hamilton to add officers for 911
Before exit can be planned, there's plenty of spadework
Something blue: Dress-less brides
Program spells out spelling
Mason waits on 3rd St. plan
Free-storage perk is over

OBITUARIES
John W. Devanney, 87, teacher, surgeon
Kentucky obituaries

OHIO
Cop killer challenges Ohio death penalty
50 years late, vet gets his medal
Ohio has to pay millions to drunk drivers
Dayton nervous over nerve gas residue
Lakefront owners, Ohio grapple over land rights
Ohio moments

KENTUCKY
Diocese suspends pastor in Gallatin Co.
Kentucky News Briefs
State Dems want Fletcher to pay for Bush's visit
Patton order to equalize state workers' health premiums
Cool-headed teenagers save bus driver
Memory expert gives tips to learn more, study less
Insurance tax draws seniors' fire
Kentucky to do
Turtles get lift back to sea