Anyone else??? (Fluid in chest cavity)

KMom14

We've been having ultrasounds every 2-3 weeks for different things they've found "wrong" with LO...it started with a hole in his heart, then he was measuring 2-3 weeks small, and today they found a little lymphatic fluid on one side of his chest cavity that wasn't there previously.  They're not too concerned with his heart (we have a pediatric cardiologist lined up to monitor him after birth), and his movement & blood flow are good, so they're monitoring his size.  The doctor couldn't tell me why the fluid was appearing now...he gave me every possible outcome from it will go away on it's own, to it needing to be drained, to it possibly signaling a chromosomal abnormality (we opted out of genetic testing earlier in the pregnancy).  Has anyone had experience with something like this??? If so, what was the outcome?  I'm not having much luck googling this, and I'd appreciate any insight right now!  Thank you!