Because in any instance where a prelim dx would be desired is way too important to have a trainee giving it. Radiology is more of a triage field while pathology is a definitive field. Wrong prelim dxs could cause umpteen problems in many cases. Heck ,we hear about groups that don't want anyone without five years post training experience. There is a reason for that. Even after residency we are still apt to cause problems. Imagine a 2nd year resident. Yes first year and second year rad residents can read middle of the night films, but they don't give chem or chop of limb or tell someone they have cancer based on radiology
I think pathstudent makes a very strong point here.
Interesting, because although I feel I understand the argument, I don't really agree. If you don't think imaging is "definitive" in terms of determining the next step in management, ask someone who gets their skull, chest, or abdomen opened when it turns out there was nothing to treat. And, really, I've seen and heard many cases where imaging + clinical correlation = cancer diagnosis, without bothering with a tissue diagnosis -- mostly individuals with other problems who generally go straight to palliative care, but that's a pretty significant decision in and of itself, no? I do, however, think that most surgeons/physicians performing a significantly invasive procedure without waiting for a final report (trauma, acute hemorrhage/perforation, etc.) take at least a half second to look at the images themselves before sinking steel into flesh. They may be wrong or the images misleading, but they share responsibility. In pathology they often don't, despite the common comment "clinical correlation is recommended" or in this case "preliminary interpretation only, final results are pending."
Of course, I also think that with rare exceptions a "prelim" pathologic diagnosis can and should be ignored by clinicians for immediate treatment purposes until a "final" is released. It's NOT that hard to NOT tell a patient "there's no tumor!" until the final is actually available, but it still allows clinicians to begin to mentally prepare for a possible next step -- exactly what, I think, prelims are for. If the final is that important to them, they'll call, and give residents all the more opportunity to learn what to do (and not to do) for next time.
That pretty much leaves frozen sections and peripheral smears in some circumstances, where a rapid confidently accurate interpretation makes a significant difference, which I think can be addressed without cutting the legs out from under pathology residents trying to become independent pathologists.