FILTRATION AND RECIRCULATION OF EARLY AMNIOTIC-FLUID - EVALUATION OF CELL-CULTURES FROM 100 DIAGNOSTIC CASES

Due to the low cell concentration, cultures from early amniotic fluid specimens usually require 2-3 weeks in culture prior to karyotyping. T he purpose of this study was to evaluate the culture quality of amniot ic fluid cells from early pregnancy, obtained by a new filter techniqu e. The hypothetical advantage of the technique was that the increased cell yield might reduce the culture time before karyotyping. Culture q uality was assessed by the number of colonies, the percentage of colon ies containing mitoses in filter and control cultures, and the culture time. The setting was a consecutive clinical trial. One hundred sampl es were obtained from ongoing pregnancies at 11-14 weeks of gestation (mean 12.8 weeks). By circulating a mean of 26 ml of amniotic fluid th rough a cell filter system leading the cell-free fluid back to the amn iotic cavity, the cell yield was increased in the sample of 7 ml corre sponding to the dead space of the filter system. The culture results w ere compared with control cultures from 5 ml samples drawn from the sa me pregnancies prior to recirculation. The cultures from the first flu shing of the Biter system yielded 26 times more colonies and in total 4.2 times more colonies were found in the three cultures grown from ea ch filter sample when compared with the control cultures. Moreover, th e filter cultures showed significantly more colonies with mitoses. The mean culture time was 8.0 days for the filter cultures, from which th e karyotypes were analysed. The controls would have needed more time i n culture to fulfil the diagnostic criteria for karyotyping. One case of 47,XY, +21 was found; the rest had normal karyotypes. We conclude t hat the filter technique improves the culture quality of early amnioti c fluid samples and allows early arrest of the cultures.