Aortic enlargement in 5 mo. old

Recently we had what we thought were routine tests run on our 5 month old to check for any heart conditions. Her father has Marfan Syndrome. Although our child has not shown any significant signs of having Marfan, testing is of course recomended. My question or issue is this: Are echocardiograms easy to misread?? Our daughter's heart was checked via an in-depth ultrasound when I was 25 weeks pregnant. Test result were "fantastic". No worries. She was checked again yesterday. She had blood pressure checks, heart rate checks, and ekg, and an echo. When all the tests were read, we sat down with the doctor who told us that all the results looked great. He told us he wanted to see us in one year, etc. etc. When he left the room, we started dressing our daughter. Within 5 minutes, the doctor was back in the room saying his practicing partner looked at the test results and found a 2.6 dialation and this was considered mildly enlarged. They have determined from this one test that she has Marfan Syndrome and want to enroll her in a clinical trial.

How could one doctor read the exact same test results and find it OK, and the next one finds a problem? They were both LOOKING for the same thing. All other heart factors are 100% fine. No valve issue, no flow issues, whatever. Just a slightly enlarged aorta. Does this sound 100% sign, sealed and delivered, or should I be seeking a second opinion??? I have read elsewhere that 2 to 3 cm is considered normal??? What is the deal?

[crystalhanzelka]

I know nothing about this really.  But if it were my child I would deff get another opinion.  And yes two different doctors could interpret differently.