Moderately increased risks of Down's syndrome (1/51-1/270) identified on first trimester sequential screening: what do patients do with this information?

OBJECTIVE: To document patient decisions after being informed of a first trimester sequential screen Down's syndrome risk between 1/51 and 1/270. SETTING: A database analysis of sequential screen results for patients seen in the Philadelphia, PA (USA) area between January 2006 and March 2008 was examined. METHODS: All patients with first trimester sequential screen Down's syndrome risks in the 1/51-1/270 range were identified. Patient decisions regarding invasive testing (prior to completing the second trimester stage of the sequential screen), completion of the second trimester blood draw or no additional testing were tabulated. RESULTS: A total of 10,850 patients underwent first trimester sequential screening during this interval. Five hundred and fifty-seven patients (5.1%) met the study inclusion criteria and had risks between 1/51 and 1/270. Ninety-three percent of these patients completed the sequential screening process before making any decisions regarding invasive testing. Four percent did not elect an invasive prenatal diagnosis procedure, but also did not complete the second trimester sequential screening blood draw and only 3.2% elected an invasive procedure based on their first trimester risk without completing the second trimester blood draw. Five women (0.9%) with low risks after the second stage screen chose to have an amniocentesis. CONCLUSION: The vast majority (97%) of patients in the moderately increased Down's syndrome risk range (1/51-1/270) following first trimester sequential screening did not pursue an invasive procedure based on their first trimester sequential screen risk. Using a > or = 1/50 risk cut-off in the first trimester is an effective screening policy for sequential screening.

Biochemical screening for aneuploidy in ovum donor pregnancies.

OBJECTIVE: The purpose of this study was to compare the screening efficacy for aneuploidy detection in ovum donor pregnancies with the use of either the age of the ovum donor or the ovum recipient. STUDY DESIGN: Second-trimester biochemical screening for aneuploidy with alpha-fetoprotein, unconjugated estriol, and human chorionic gonadotropin was performed on maternal serum samples that were submitted prospectively from singleton ovum donor pregnancies. The calculation of aneuploidy risks were performed separately with the age of the ovum donor or the ovum recipient. Risks of >1 in 295 and >1 in 100 were used as cutoff values for the identification of screen-positive pregnancies for Down syndrome and trisomy 18, respectively. RESULTS: Samples from 93 ovum donor pregnancies were identified. The mean ages of the ovum donors and recipients were 27 years (range 20-38.5 years) and 43.6 years (range, 25.9-54.3 years), respectively. When the age of the ovum donor was used in the determination of aneuploidy risk, there were 9 screenpositive pregnancies (9.7%), whereas the use of the age of the ovum recipient resulted in 76 screen-positive pregnancies (82%). With the use of the McNemar test for paired observations, the proportion of screenpositive pregnancies with the age of the ovum donor (9.7%) compared with the age of the ovum recipient (82%) was statistically significant (P <.0001). The odds of being affected, given a positive result, were 1 in 9 (11%) with the age of the ovum recipient and 1 in 76 (1.3%) with the age of the ovum donor. The only fetus with aneuploidy (trisomy 18) was identified as being screen positive in both the ovum donor and ovum recipient calculations. CONCLUSION: In ovum donor pregnancy aneuploidy risk calculations, the use of the age of the ovum donor instead of the ovum recipient reduces the false-positive rate and improves screening efficacy.