A complete hydatidiform is another oddball complication of the menstrual cycle and pregnancy. Normally, in every menstrual cycle one competing follicle becomes the dominant follicle or Graafian Follicle. In the process of ovulation (see figure below) that follows the hormone luteinizing hormone (LH) promotes a sequence of events. Firstly it promotes the egg to undergo the first stage of meiosis, or generating a haploid or ½ set of chromosomes to combine with the haploid or ½ set coming from the fertilizing sperm. Secondly it promotes the formation of stigma or projection in the follicle to aid the eggs ovulation. Thirdly it promotes the production of digestive enzymes to burn a hole in the follicle, and fourthly it promotes the release or ovulation of the egg.
Rarely, this complicated set of events goes wrong. Usually ,due to an inappropriate LH peak. In complete hydatidiform mole meiosis or generation of a haploid set of ½ set of chromosomes fails. The result is an an empty egg is ovulated, or an egg without chromosomes to donate. This egg can be fertilized by one sperm, the sperms ½ set finds no egg ½ set to pair, the sperm ½ set duplicates itself, then fertilizes itself. Alternatively, 2 sperm can provide ½ sets or haploid sets (if cortical granules also fail, see “partial mole”). The end result is a fertilized embryo of diandrogenous or all male chromosome origin. This grows and develops to become an 8 cell morula. At the morula stage the first differentiation must occur into fetal and placental tissue. By default it becomes 100% placental tissue. This is a complete hydatidiform mole. A complete hydatidiform mole is identified in pregnancy by ultrasound. A classical snow flake picture is seen with no fetus. The complete hydatidiform mole placental mass must then be terminated by Dilation and Curettage. One complication of complete hydatidiform moles is invasive or persistent moles. Invasive or persistent moles occur in approximately one third of cases of complete hydatidiform mole.