Monday, November 17, 2008

surg path basics

OK, I've been off surg path (and on autopsy) for a few weeks now, but I am finally getting around to posting about the service. Sorry for the delay. Yesterday, one of my friends in a surgery residency across the country called, asking me exactly what pathologists do regarding surgical specimens. I figure that's as good a topic as any to start this off with.

There are four main "duties" that pathology residents have during surg path. At my institution, we cycle through these every few days, then start over.

1. Frozen sections. Let's say a surgeon is dealing with a nasty invasive cancer. He cuts it out, but he wants to make sure he got all of it. He takes a margin (ie, a piece of tissue just past the edge of the tumor) and sends it to the frozen section room. There, the pathologist cuts the tissue up, freezes it with a special compound, uses a cryostat (a machine that holds the frozen tissue in place and cuts super-thin slices of it) to place a piece of the tissue on a slide, stains the slide with hematoxylin and eosin, then looks at it under the microscope to say whether there's cancer there. The slides this technique produces aren't quite as good as "permanent" slides (see below), but they'll do in a pinch. If there's cancer in the margin, the surgon has to go back and take out more tissue. Frozens are done for various other reasons, including transplant viability (they want to put a fresh liver in a patient -- how healthy is it?). Making a frozen section isn't terribly difficult, but some tissues are hard to orient or cut properly, and when five surgeons send you specimens all at at once and wonder what's taking the lazy pathologist so long (hint: you're fourth in line!), it can get quite hectic.

2. Grossing. Anything that gets taken out during surgery -- a gallbladder, a cancerous kidney, a diabetic leg, a jaw full of tumor -- gets sent to us for grossing. Basically, we inspect the tissue, describe it, cut it open, and take representative sections. For the gallbladder, that means one section of mucosa (to see if it's inflamed) and one section of the cystic duct margin (to see if it's blocked). For the cancerous kidney, we take sections of the cancer (to see what kind of cancer it is) and sections around the cancer (to see if the cancer invaded the capsule / fat around the kidney / draining system of the kidney / renal vein / etc.). And so forth. This is a lot harder than it sounds, especially with weird specimens (the aforementioned jaw), complicated specimens (a Whipple -- ie, parts of stomach, pancreas, duodenum, and sometimes more), and annoying specimens (any colon cancer requires that we find ten lymph nodes in the fat -- which means mashing through the fat and hunting for tiny lymph nodes, usually for 90-120 minutes per colon). These days can run long; the last processor cuts off at 9 p.m., and that deadline is sometimes missed. The pieces of tissue removed from these specimens get placed in a processor and fixed in formalin overnight. The next day, they are turned into "permanent" slides in a more controlled and clean version of the "frozen section" procedure described above. The histology technicians handle that part.

3. Previewing cases. Once the slides are out, the resident looks at them before signing out with the attending. A fourth-year resident can make most diagnoses and get all the paperwork in order without breaking a sweat. Me, as a first year? I'm usually happy if I can tell it's a cancer, any cancer. Forget identifying, staging, etc. We also have to look up clinical history on the patients, and sometimes we order special immunostains. These stains come in handy for diagnosis (is this skin lesion melanoma? order a S100 stain and see if it's positive) and/or prognosis (breast cancer, eh? is it ER and PR receptor positive?). Especially as a first year, these are actually your longest days. Just getting the paperwork in order takes forever, and if you're giving the slides a good honest look, be sure you brought some cash so you can get dinner and coffee from the hospital cafeteria.

4. Signing out cases. This involves sitting with the attending, giving them whatever information they may need about the clinical history or the gross findings, and listening to them teach you why something is what it is. Usually somewhat painless, though each attending has his own style of doing things, and you're always preoccupied handling the small tasks you forgot to take care of while you were previewing the day before.

There are other little things we have to do, including preparing surgery schedules for the next day so we always know what frozen sections to expect, but this covers the bare bones. In future posts, I'll dive into more detail on each of these points, as well as discuss the other crazy things that always pop up on the surg path service.

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