Final answer:
The classic ultrasound appearance of a complete hydatidiform mole is a 'snowstorm' or 'cluster of grapes' pattern, with no fetus or gestational sac evident. Grossly, it appears as a collection of grape-like vesicles of varying sizes filled with clear to yellow fluid, giving a swollen, edematous appearance to placental tissue.
Step-by-step explanation:
A complete hydatidiform mole is a type of molar pregnancy which is a gestational trophoblastic disease. In a complete mole, there is an absence of an actual fetus and characteristic features are observed both in ultrasound and in the gross morphology of the extracted tissue. Ultrasound findings typically include a 'snowstorm' or 'cluster of grapes' pattern, with a heterogeneous mass containing numerous small cystic spaces giving the appearance of exaggerated placental tissue without a recognizable embryo or fetus.
The gross appearance of a complete mole often resembles a bunch of grapes. This aspect is due to the presence of vesicles, which are varying in size, ranging from very small to several centimeters in diameter and contain clear to yellow fluid. Together, these cysts create a swollen, edematous placental tissue with no normal placental villi apparent.