Placentas in late abortions associated with chromosomal abnormalities (trisomy 13, 18, 21 and monosomy X in particular) may show abnormal gross or histologic features.
The placenta may be either large or small for gestational age. Rarely cysts may be grossly recognizable.
Placenta in trisomy 13, pregnancy termination at 23 w.g.; placenta with scattered large vesicles: Placenta, syndrome Patau, Macro, autopsy (72868) Placenta, syndrome Patau, Macro, autopsy (72869)
These features are not neither specific or constant in chromosomal abnormalities and cannot be used for diagnosis as the only sign.
Placenta mimicking partial mole, huge hydropic villi, poor vascularization, no trophoblastic hyperplasia, normal villi: Placenta, trisomy 13, HE 20x (72806) Placenta, trisomy 13, HE 40x (72807)
Placenta in trisomy 21, 40-week stillborn infant, retardation of villous maturation, aberrant vasculary pattern, choriangiosis: Dystrophic placenta, Down syndrome, HE 20x (72866)