What is the characteristic appearance of gestational trophoblastic disease (GTD) on ultrasound?

Choice A rationale Gestational trophoblastic disease (GTD), specifically a hydatidiform mole (molar pregnancy), is characterized by the overgrowth of placental tissue. On ultrasound, this manifests as a uterine cavity filled with numerous cystic spaces representing edematous chorionic villi. This distinctive sonographic pattern is often described as a "snowstorm" or "grape-like clusters" appearance, due to the absence of a viable fetus and cystic transformation of the villi. Choice B rationale Multiple small cysts in the ovaries are characteristic of conditions like Polycystic Ovary Syndrome (PCOS) or physiologic follicular cysts. Although Theca-lutein cysts are ovarian cysts that can occur in women with GTD due to hyperstimulation from high levels of human chorionic gonadotropin (hCG), they are a secondary ovarian complication and not the characteristic uterine appearance of the GTD itself. Choice C rationale Enlargement of the fallopian tubes is typically associated with conditions such as ectopic pregnancy (tubal pregnancy) or pelvic inflammatory disease (PID) (e.g., hydrosalpinx, pyosalpinx). Gestational trophoblastic disease is primarily a uterine pathology involving the abnormal proliferation of placental trophoblasts. Tubal enlargement is not the characteristic ultrasound finding for GTD. Choice D rationale Thickening of the uterine lining (endometrial thickening) is a non-specific finding that can be seen in normal pregnancy, endometrial hyperplasia, or endometrial cancer. While GTD involves abnormal growth within the uterus, the thickening is specifically due to cystic, hydropic villi which gives the unique "snowstorm" pattern, rather than a simple uniform thickening of the lining seen in other conditions.