Date Approved


Graduate Degree Type


Degree Name

Physician Assistant Studies (M.P.A.S.)

Degree Program

Physician Assistant Studies


OBJECTIVE: Our goal was to evaluate whether a normal ultrasound following a positive triple marker serum screen reduces the risk of having a trisomy 18 fetus to a level that is less than the procedure-related risk for amniocentesis. STUDY DESIGN: A nonrandomized, non-concurrent cohort chart review was performed of all women who screened positive (risk > 1:250) for trisomy 18 by triple marker serum testing through Spectrum Health Downtown Genetic Screening Program from June 1996 through September 1999. Of the 13,618 serum samples screened, 158 were identified as being at an increased risk for trisomy 18. Pediatric outcome was obtained through office documentation, review of birth records, or phone contact with the mother. RESULTS: Four cases of trisomy 18 were identified and all had abnormalities on ultrasound. CONCLUSION: The presence of normal ultrasound was not associated with significant increased risk for trisomy 18. In this population, amniocentesis is not justified.


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