William Mason remained in intensive care Thursday at Yuma Regional Medical Center, two days after the accident, the Yuma Daily Sun reported.
"We'll have to see how the surgery goes to learn the extent of his injuries. It was a horrible accident," Caroline Ashley, Mason's mother-in-law, told the newspaper. "He's in very serious condition. We don't even know if he will live. We're all praying for him."
Ashley said Mason also suffered a broken leg and 146 cactus spines had been removed from his body.
Mason, 40, a water distribution technician, and other members of a crew were working on a leak when the 14-foot cactus tipped over on him. Full-grown saguaros weigh from 3,200 to 4,800 pounds and are held in place by a network of shallow roots, anchored by a single deep tap root.