Matt Hardy talks about his return to the ring, and the abdominal injury he worked through before and during his ten year WWE career, on his WWE Universe blog:

On a very interesting side note, August 21st, 2009, marks the first time I’ve ever actually wrestled a match with an abdominal tear/hernia. When I was in 7th grade, during a standard sports physical, I was diagnosed with a inguinal hernia on my lower left side of my abdomen. The doctor that performed my surgery also informed me that a had an abdominal tear on my right side as well that would one day probably need to be corrected. The Doc said it wasn’t bad enough to be fixed then, but any sports or physical contact would obviously make it worse. I discover wrestling. I fell in love with the idea of being a professional wrestling, particularly for the WWE. As I worked independent shows, my right side abdominal tear never bother me. I almost chalked it up to one of those things that I was just gonna be able to live with the rest of my life and it wouldn’t be a problem. Once I joined the WWE and started on a full-time schedule, once every few months my intestines would slightly bulge or swell, and I would just push them back in. And then it would be months before this happened again. So I figured it wasn’t that big of a deal, the last thing I wanted to do was take time off to get something fixed that really wasn’t even bothering me. Fast forward almost ten years.

Yes, he worked through intestinal bulging for years. He goes on to talk about how his appendicitis finally made his abdominal tear an issue he couldn’t ignore, and why he decided to work through that injury without telling WWE about it anyway:

I remember wrestling Jack Swagger at a live event and feeling a painful tear of my abdomen. I had to have this fixed. The pain and discomfort of this injury was affecting my physical look, my in ring work, my training in the gym, almost every aspect of my career.. Everyday was a hard day for me at this point. Next thing you know, I’m embroiled in one of Smackdown’s hottest issues that would ultimately lead to myself wrestling Jeff at Wrestlemania. There was no way in the world I was gonna miss that-another dream of ours as kids was to wrestle one another on the grandest stage of them all, Wrestlemania.

He also provides a graphic photo of his intestinal bulging after his abdominal tear in a match against Kofi Kingston and MVP for your viewing pleasure. He also has a disclaimer, for any impressionable types in the audience:

And just for the record, only 2 people knew about my condition, as I kept it hidden from WWE officials because I knew they would have pulled me from active duty immediately. Bottom line is this-kids don’t try this at home or do what I always do, LOL.

I mean, you don’t want intestinal bulging, do you?