Blues singer Etta James is in stable condition in a Los Angeles hospital, suffering from complications following abdominal surgery, her manager said on Wednesday.

The 69-year-old rock 'n' roll pioneer was admitted to Cedars-Sinai Medical Center, following the mid-June surgery, Lupe De Leon wrote in an email to Reuters. James hopes to be well enough by the end of August to join blues icon B.B. King and soul veteran Al Green on a tour that began in Florida on Tuesday.

"If it had been left solely up to her, she would have checked herself out of the hospital and started the tour regardless of her delicate health," De Leon said. "However, her doctor advised that were she to do so, it would put her at very great risk."

R&B singer Chaka Khan is substituting for James on the tour.

James helped pioneer rock 'n' roll in the mid-1950s with tunes such as "The Wallflower" and "Good Rockin' Daddy." She diversified into mainstream blues, soul and R&B during the 1960s, after signing with Chess Records. The three-time Grammy winner was inducted into the Rock and Roll Hall of Fame in 1993, and remains an active recording artist.