Little is known about how the marketplace for hospital send-out testing is divided among national laboratory competitors.These rankings mark the second year THE DARK REPORT has attempted to measure the market for hospital esoteric and reference testing. This ranking does not include niche or specialty laboratory companies which provide specific lines of testing to hospital laboratories. Each company had the opportunity to make corrections and provide additional input as appropriate. Further, some of these national laboratories do not track hospital send-out testing as a separate category. Thus, even self-reporting has certain inaccuracies which must be acknowledged.