Nasal Bone Check Improves Trisomy 21 Detection
Adding check to combined testing detects 90 percent of cases with 2.5 percent false-positive rate
TUESDAY, July 18 (HealthDay News) -- Assessing the nasal bone during first-trimester trisomy 21 screening detects nine of 10 cases, with a 2.5 percent false-positive rate, researchers report in the July issue of the American Journal of Obstetrics & Gynecology.
Simona Cicero, M.D., of King's College Hospital in London, U.K., and colleagues compared integrated first-semester screening for all patients and first-stage screening of all patients using fetal nuchal translucency thickness and maternal serum, plus second-stage nasal bone assessment only for those with intermediate second-stage risk.
The researchers found that first-trimester nuchal translucency added to serum testing yielded a 90 percent detection rate, and a 5 percent false-positive rate. Including the nasal bone in combined testing cut the false-positive rate to 2.5 percent.
"If the expertise for examination of the nasal bone is not available in the primary screening center, the patients in the intermediate-risk category could be referred to a more specialist unit to undergo such examination and readjustment of risk," the authors write.
In an accompanying editorial, Yves Ville, M.D., Ph.D., of Paris-Ile-de-France-Ouest Medical School in Poissy, France, writes that "standardization of nasal bone imaging is a critical step."