Patient decisions regarding prenatal aneuploid fluorescence in situ hybridization results

Objective: To determine an appropriate risk cut-off to offer prenatal aneuploid FISH, and if FISH results affect patient decisions regarding pregnancy management. Method: Retrospective evaluation of 707 patients presenting for diagnostic prenatal testing. Studied parameters included gestational age, indication for testing, aneuploid risk, procedure performed, FISH (whether offered, requested, and/or performed), result turn-around time, karyotype results, decision after obtaining results, and the timing of that decision. Patients who were offered FISH were compared to those not offered FISH (student T-test). Results: Twenty-five clinically significant abnormalities were detected by karyotype and/or FISH analysis. Thirteen out of 17 patients electing pregnancy interruption had FISH performed. There were no differences between the group that interrupted following FISH (n=7) and the group that interrupted following final karyotype results (n=6). Turn-around times for those abnormal samples with FISH testing was significantly shorter than for those without FISH testing (p=0.02). Risk thresholds of >= 0.5%, >= 1 %, >= 2%, or >= 3%, would detect 92%, 84%, 48%, and 32% of the clinically significant anomalies with 663, 317, 118, and 66 FISH analyses performed, respectively. Conclusion: Acting on FISH results alone afforded a significantly shorter interval between test and pregnancy interruption. A risk cut-off >= 1 % appears to optimize the detection rate and the yield of abnormal results. (c) 2006 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.