·         Complete mole- Echogenic material fills the uterus, there is no fetal tissue, the mass is echogenic but does not cause a great deal of ultrasound beam attenuation. Vesicles are usually less than 1.5 cm in the first trimester but may be over 2 cm in diameter in the second trimester. Later confluent hypoechoic areas occur due to hemorrhage. Ovarian cysts may be evident (30—50%).

 

·         Partial mole- Coexistent mole and fetal parts. The fetus shows multiple anomalies and severe IUGR. There is a high incidence of chromosomal abnormalities in the fetus. Sonographic demonstration of molar vesicles together with a well formed fetus and a normal placenta suggest coexistent mole and fetus. Unlike partial moles these demonstrate the same potential for malignant change as the classical moles and may be due to a twin pregnancy, one fertilized product giving rise to the mole.

 

·         Invasive mole- Locally invasive hydatidiform mole accounts for up to 15% of cases sonographic1Y. This is seen as an enlarged uterus containing a molar mass with foci of increased echogenicitY extending into the myometrium. Anechoic areas may be present due to areas of hemorrhage and necrosis and appearances may be indistinguishable from other uterine tumours.

 

·         Hydropic degeneration of placenta- Hydropic degeneration IS not a hydatidiform mole variant because it involves the placenta without histologic evidence of tropho blastic proliferation. The overall appearances depend upon the extent of vesicular change, hemorrhage, necrosis and breakdown products of conception. It may be very difficult to differentiate from a partial mole sonographically.