Large Upper Abdominal Incisional Hernia?

Here's the background:

In Spring 2008, I had a giant paraesophageal hiatal hernia repaired. This required a full breastbone to navel incision. The stomach and part of large intestine were herniated above the diaphragm. No mesh was used anywhere in this repair, including the abdominal incision.

This seemed to be OK until Fall 2008, when I went to the ER with an incisional (ventral) hernia, just above the navel. This was repaired with an open incision, and mesh was applied in the lower abdominal area. This was a different surgeon than the hiatal hernia repair in the spring.

For about two months this seemed to be healing fine. Then around New Years, the upper abdomen along the incision line, above the incisional repair, between the (about 6 inches long) started swelling. The entire upper abdomen is now swollen, hard and distended - about 2 inches, at least. Very sore.

The surgeon who did the repair sent me for a Cat-scan. He thought the upper part of the incision was herniated too, by examination. But upon review of the Cat-scan, he and the radiologist both claim that he sees no hernia! I have reviewed the scans and at that section, it sure looks like the upper abdominal wall is split apart, to my untrained eyes.

I am going to see this surgeon again, but I am quite concerned about this situation.

Questions:

Is it possible to not be able to see a massive upper abdominal hernia with a cat-scan?

If it ISN'T a hernia, I feel I should be asking for some plan or direction to diagnose this. What sort of specialist would one see to get to the root cause or upper abdominal swelling?

I am assuming it IS a giant ventral hernia, nothing else really makes sense.

Has anyone here have an upper abdominal ventral hernia repair? My understanding is that this can be a very difficult area to repair, with a significant risk of recurrence.

Thanks.