A patient came in last month, nervous, the week before a knee replacement. Her surgeon had said the words "clearance" and "labs," and she wasn't sure what either meant. Was something wrong with her? Did she fail a test she didn't know she'd taken?
Nothing was wrong. She was doing exactly the right thing.
A pre-op laboratory panel is a set of blood tests we run before surgery to make sure your body is ready for the stress of a procedure and the medications that come with it. It isn't a test you pass or fail. It's a snapshot — a way for me, your surgeon, and your anesthesiologist to see what's happening under the hood before anyone makes the first incision. In my Los Angeles practice, I think of it as preparing the ground so that surgery day holds as few surprises as possible.
What does a pre-op laboratory panel actually check?
A pre-op laboratory panel checks the things that most affect how you'll handle surgery: your blood, your organ function, your clotting, and your chemistry. The exact tests depend on you — your age, your health history, the type of surgery, and what medications you take.
That said, a few show up often:
- A complete blood count (CBC) looks for anemia or infection and gives us a baseline platelet count, which matters for clotting and bleeding.
- A complete metabolic panel (CMP) checks kidney function, liver function, blood sugar, and electrolytes — all of which influence how your body processes anesthesia.
- Coagulation studies tell us how well your blood clots, especially if you take a blood thinner.
Depending on the situation, I may add thyroid testing, an A1c if you have diabetes, or a few others. Tailoring matters. Ordering every test on every patient isn't thorough — it just generates noise.
Why do I need bloodwork if I feel fine?
Because some of the conditions that complicate surgery are quiet ones, and bloodwork is how we catch them early. Mild anemia rarely announces itself. Neither does a kidney quietly working at lower capacity, or a thyroid that's drifted out of range.
I've had patients who felt perfectly healthy and turned out to have borderline numbers worth addressing first. Finding that a week or two before surgery is a small inconvenience. Finding it on the operating table is a real problem.
This is the heart of being medically optimized — fixing the small, fixable things in advance so your body shows up to surgery in the best shape it can.
How is a pre-op panel different from pre-op clearance?
The lab panel is the bloodwork; clearance is the larger judgment that uses it. The labs are one piece of evidence. Pre-operative risk assessment pulls together your history, your physical exam, sometimes an EKG, and these results into a single picture of how ready you are.
So when your surgeon asks for "clearance," they're really asking: has someone looked carefully at the whole patient? The lab panel helps me answer that honestly.
How should I prepare for the blood draw?
For most pre-op panels, very little — but always check whether yours requires fasting, since some tests do. Bring an updated list of every medication and supplement you take, including the ones you might not think to mention, like fish oil or a daily aspirin. Those affect bleeding and timing more than people expect.
Here's what I tell patients about timing: don't wait until the last minute. We want the results back with enough runway to act on anything we find. If a number needs a recheck or a quick adjustment, we'll have room to do it calmly.
What happens if something comes back abnormal?
An abnormal result almost never means surgery is off — it usually means we have a small problem to solve first. Maybe your iron is low and we treat the anemia. Maybe a blood thinner needs a careful pause and restart, coordinated with your surgical team. Maybe a number was off and a simple repeat test sets it right.
My job is to walk you through what we found, what it means, and what we'll do about it. You should never leave that conversation confused. If you do, ask me again — I'd rather repeat myself than have you worry over the weekend.
If you've got surgery on the horizon and you're not sure where to start with your labs, I'd genuinely like to help. Reach out and let's talk — we'll figure out exactly what you need, get it scheduled with time to spare, and make sure you walk into your procedure feeling prepared rather than anxious. That's the whole point.