Vitrification is caused by the growth of placental chorionic trophoblast cells and swelling of the interstitial fluid, resulting in the formation of large and varied vesicles, which are then linked together by their stalks to form clusters that resemble grapes, also known as vesicular masses.
Grapes can be categorized as complete or partial. The most common symptom is vaginal bleeding after menopause.
Typical ultrasound image of complete hyperemesis gravidarum is that the uterus is larger than the corresponding gestational week, with no gestational sac or fetal heartbeat. The uterine cavity is filled with heterogeneous, dense or short echoes in the form of a “snow fall”, or a “honeycomb” when the bubbles are large. Ovarian cysts may be detected in both or one side of the uterus. The uterine artery may be rich in fluid, but there is no or only sparse fluid signal in the muscular layer of the uterus.
Partial gravidarians may show ultrasound changes in the placental area caused by focal vesicular masses, sometimes with fetal or peritoneal cavities, and often with fetal abnormalities.