Ploidy analysis of products of conception by image and flow cytometry with cytogenetic correlation

Ploidy analysis of hydropic placentas is used in conjunction with morphology and clinical data to classify hydatidiform moles and hydropic abortuses. In most studies, ploidy has been assessed by flow cytometry (FCM). To validate image cytometry (ICM) as a method to determine ploidy in this setting, the authors used both FCM and ICM to study 19 hydropic placentas in which cytogenetic analysis was available. Nuclear suspensions from paraffin-embedded tissue were used for both ICM and FCM. Image cytometry of tissue sections was performed in some cases. Image cytometry and FCM were concordant in all 19 cases, but discordant with cytogenetics in 2 of 19 cases. Two hydropic abortuses (HA) with a diploid karyotype were triploid and tetraploid, respectively, by both ICM and FCM, which suggested that the cultured tissue was not representative. DNA indices were most accurate when an internal diploid control was used as the reference. In ICM, higher resolution was achieved by analyzing cell suspensions rather than tissue sections. This study shows that ICM is a valid method of determining ploidy of hydropic placentas and partial hydatidiform moles in archival tissue.