Typical characteristics of complete and partial hydatidiform moles
| Characteristic | Complete hydatidiform mole | Partial hydatidiform mole |
| Ploidy | Diploid | Triploid |
| Genome | Diandric | Diandric monogynic |
| Karyotype | 46 XX/XY | 69 XXX/XXY/XYY |
| Ultrasound imaging | Enlarged uterus, bilateral theca lutein cysts, diffuse villous hydrops | Enlarged placenta, focal cystic spaces, growth restricted fetus |
| hCG (IU/L) | >100 000 | <100 000 |
| Pathology | Fetal tissue usually absent; diffuse enlargement of villi; cisterns; diffuse trophoblast hyperplasia; trophoblast pseudoinclusions; bulbous, cauliflower-like villous outlines in earlier gestations; villous stromal karyorrhexis in earlier gestations. | Fetus with anormalies; mixed population of enlarged and small villi; occasional cisterns; focal trophoblast hyperplasia; trophoblast pseudoinclusions; very irregular villi with fjord-like invaginations. |
| p57 immunohistochemistry | Loss of p57 staining in cytotrophoblast and villous stromal cells. | No loss of p57 staining. |
| Risk of GTN progression1–3 | 15-20% | 0.5-1% |
hCG=human chorionic gonadotrophin. GTN=gestational trophoblastic neoplasia.