The Management of Gestational Trophoblastic Disease

Molar pregnancies can be subdivided into complete (CM) and partial moles (PM) based on genetic and histopathological features. Complete moles are diploid and androgenic in origin, with no evidence of fetal tissue. Complete moles usually (75–80%) arise as a consequence of duplication of a single sperm following fertilisation of an ‘empty’ ovum. Some complete moles (20–25%) can arise after dispermic fertilisation of an ‘empty’ ovum. Partial moles are usually (90%) triploid in origin, with two sets of paternal haploid genes and one set of maternal haploid genes. Partial moles occur, in almost all cases, following dispermic fertilisation of an ovum. Ten percent of partial moles represent tetraploid or mosaic conceptions. In a partial mole, there is usually evidence of a fetus or fetal red blood cells.