Dave Meltzer of Wrestling Observer Radio reported Rousey suffered a broken hand in her Triple Threat match with Becky Lynch and Charlotte Flair, per Marc Middleton of WrestlingInc.
Rousey lost her Raw Women's Championship when she was rolled up and pinned by Lynch in a controversial finish. Sean Ross Sapp of Fightful reported the finish was unplanned and that Rousey was angered because "the situation made her look bad."
It's unclear if the finish was a botch or planned to be "controversial." It was Rousey's first loss in a WWE ring, and she was clearly upset at the end of the match, though that could have been part of the storyline.
If WWE was trying to start its post-WrestleMania program with the finish to set up a Lynch-Rousey match, it appears that will have to wait. The extent of Rousey's injury is unknown at this time—hand breaks take varying levels of time to heal, depending on location and severity—but odds are she'll be out for several weeks.
Meltzer's report says the planned ending was for Lynch to roll Rousey up and win the match but her shoulders coming up at the end was unplanned. The original plan was reportedly for her to be "really pinned" by the roll-up.
Rousey is currently being advertised for an appearance on Monday's Raw at Barclays Center.