Monday, September 03, 2007

Detecting Danger In Unborn Babies

BACKGROUND: Just like adults, fetuses need red blood cells to carry oxygen through their bodies while they're in the womb. And just like adults, fetuses can suffer from conditions like anemia while they're in the womb. Fetal anemia is a dangerous condition for unborn babies.

Gareth Seaward, M.D., from Mount Sinai Hospital in Toronto, says, "There is a wide spectrum of problems associated with fetal anemia beginning in the uterus and occurring after delivery as well." Babies can develop heart failure and actually die in the uterus. After birth, these babies can develop high bilirubin levels -- related to red blood cells and significant jaundice -- which can result in serious neurological damage.

DETECTING FETAL ANEMIA: Not all women are at risk for their babies developing fetal anemia in the womb. The most common cause of fetal anemia in unborn babies is the incompatibility between the baby's blood type and the mother's blood type. The majority of the population has Rh-positive blood, but about 15 percent of the population has Rh-negative blood. If a woman has Rh-negative blood and has a child with a man with Rh-positive blood, her baby is at risk for developing fetal anemia. For high-risk women, doctors will typically monitor the pregnancy with ultrasound and, if fetal anemia is suspected, the woman will generally have an amniocentesis to detect the condition. Dr. Seaward says, "[Amniocentesis] is not a benign procedure. You may trigger a miscarriage; later in the pregnancy, you may trigger premature rupture of membranes and/or preterm labor and delivery." Dr. Seaward tells his patients they have at least a 1-percent risk of losing the pregnancy every time he does an amniocentesis. A better way to detect fetal anemia is needed.

EASIER, SAFER DETECTION: Dr. Seaward and his colleagues recently studied 187 pregnant women whose babies were at risk of developing fetal anemia. He studied the use and reliability of Doppler ultrasound to detect fetal anemia in women. Doppler ultrasound detects the condition by measuring blood flow through the middle cerebral artery.

Dr. Seaward says, "We are specifically looking at blood flow velocity signals using color Doppler ultrasound to determine what the peak flow velocity is. With severe fetal anemia, or fetal anemia warranting intervention, the blood flow increases its velocity rapidly."

The study shows not only is Doppler ultrasound effective at detecting fetal anemia, it's significantly better at detecting it than amniocentesis. Doppler ultrasound is performed just like a regular ultrasound and is non-invasive.

Dr. Seaward says, "As a result of that study and ongoing work, we no longer use amniocentesis at all to diagnose fetal anemia in our setting here in Ontario."

Since the publication of the study in the New England Journal of Medicine in July, 2006, he says many centers specializing in the care of women who would be at risk of having babies with fetal anemia have abandoned amniocentesis in favor of Doppler ultrasound.

Important to point out -- if fetal anemia is confirmed, the treatment then becomes invasive and consists of a blood transfusion in the womb.

Jodi Salem
Media and Communications Specialist
Mount Sinai Hospital
Toronto, ON, Canada


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