"To be clear, I blame Larry Nassar and I also blame an entire system that enabled and perpetrated his abuse," she said before the US Senate Judiciary Committee alongside fellow gymnasts McKayla Maroney, Aly Raisman and Maggie Nichols.
USA Gymnastics said that Biles would make a decision later this week on the one remaining event she is qualified for, the beam.
The 24-year-old, however, might yet make another appearance at the Tokyo Games having not ruled herself out for floor exercise on Monday and beam on Tuesday.
Biles' quest to become the greatest female Olympian took a bizarre twist, when she dropped out of the women's team event after one vault.
The American squeezed into the uneven bars final thanks to an Olympic rule that limits only two finalists per nation, with two higher-placed Russians missing out.
USA Gymnastic tagged the wrong account rather than the four-time Olympic champion's verified account. Three hours later, Biles issued a tweet of her own.
Two falls on an 'off day' did not prevent Biles from becoming the first woman to win four all-around titles at the Gymnastics World Championships in Doha.