Possible causes are wide ranging, including trauma from a knife wound or eating a sharp object; a medical procedure such as a colonoscopy, cancers, ulcers or infections.
It can lead to sepsis and can be fatal.
The 48-year-old actor is an outspoken addiction recovery advocate after struggling with addictions to alcohol and several prescription drugs during his time on Friends.
In 1997 he completed a 28-day program for Vicodin addiction, later telling Larry King that he took the painkiller "mostly just to not drink as much as I was."
In 2001 he entered a rehab to recover from his use of Vicodin, methadone, amphetamines, and alcohol.
Perry became one of the most famous faces on the planet, playing one of the six Friends in the classic 90s sitcom alongside Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc and David Schwimmer, where each was commanding $1million per episode in the show's final seasons.
Earlier this year Perry sold his home in the Hollywood Hills for $12.5million, having bought a $20million luxury penthouse apartment in Century City last year.