CYTOGENETIC ANALYSIS OF SPONTANEOUS-ABORTIONS - COMPARISON OF TECHNIQUES AND ASSESSMENT OF THE INCIDENCE OF CONFINED PLACENTAL MOSAICISM

Cytogenetic studies on spontaneous abortions traditionally have used o ne of two methodologies, direct preparations or longterm culture, to d etermine the chromosome constitution of either the cytotrophoblast or villous stroma, respectively. Few studies have utilized both technique s simultaneously to compare the relative efficiencies of each method a nd to assess the contribution of confined placental mosaicism (CPM), T he present report summarizes cytogenetic studies on 691 consecutive sp ontaneous abortions using long-term culture, direct preparations, or b oth, All 691 cases were analyzed by long-term culture and 177 cases we re analyzed using both long-term culture and direct preparation. The r esults indicate that the two methods have similar success rates, 82% f or long-term culture and 76% for direct preparation; however, the prop ortion of normal females was significantly increased in the culture me thod, presumably attributable to maternal contamination, In 107 cases, results were obtained from both methods with 22 discrepancies identif ied, However, most of these involved a 46,XX result in culture, consis tent with maternal contamination in the cultured preparation, Therefor e, to estimate the proportion of CPM we excluded cases with a 46,XX re sult in culture and found four (6.1%) of the remaining 65 cases to be consistent with CPM. These cases consisted of normal or mosaic aneuplo id cytotrophoblast and non-mosaic aneuploid villous stroma. These stud ies suggest that each method has specific advantages in the analysis o f spontaneous abortions, Direct preparations are less prone to materna l contamination, but certain chromosome abnormalities are more likely to be identified using long-term culture. (C) 1997 Wiley-Liss, Inc.