Products of Conception, Ploidy by Flow Cytometry

Diagnostic Data: Flow cytometry can be used to help identify partial hydatidiform moles. Partial moles are usually triploid while complete moles are diploid, tetraploid, or aneuploid [Clinical Medicine: Pathology, 2008;1:61-67; Gynecol Oncol, 2001;81:67-70]. However, most products of conception are diploid, so a diploid histogram does not suggest a complete mole unless supported clinically and microscopically.

Prognostic Data: Persistent trophoblastic disease occurs in about 20% of diploid and tetraploid complete moles. Aneuploid complete moles may be associated with less risk for persistent disease [Gynecol Oncol, 2001;81:67-70]. The risk of persistent trophoblastic disease after a triploid mole is very low (0 out of 105 cases) [Obstet Gynecol, 2006;107:1006-1011]. In rare cases, a triploid result can also be due to nonmolar triploidy (digynic triploidy) where the extra haploid set of chromosomes are maternal. Nonmolar digynic triploid pregnancies are not associated with gestational trophoblastic disease and do not lead to an increased risk of recurrent molar pregnancy. Differentiating between a triploid partial mole and nonmolar triploid pregnancy requires clinical, microscopic, and molecular genetic testing correlation. [Clin Case Rep. 2020;8(5):785-789].