My DS had surgery at CHOP this AM (all is well), and had to go under general anesthesia. They told me to BF up to 3 hours before, and water up to 2 hours before. If he were formula fed, that would have stopped 6 hours before.
These guidelines are in line with LLL recommendations, but the 4-2 hr recommendation you got is supported by a lot of other organizations, including the Anesthesioloists Society. You could share with them the guidelines CHOP uses and try to get the extra hour, but I don't think you'll be successful getting them to let you BF 2 hours before. It's not like they're treating BM as equivalent to formula, as fluids go.
best of luck to you and your LO. If it's any consolation, there were 3 babies this morning. The two BF babies had a MUCH easier time when they woke up, b/c they could nurse. The poor FF baby had to get apple juice in her bottle, and she was screaming so hard, it sounded like she was gargling!
Poor thing! So, BM will make a BIG difference following the surgery.