Most surgeons ask for a short set of blood tests before an operation: a complete blood count (CBC), a metabolic panel (BMP or CMP), and, depending on your health and the procedure, clotting tests such as PT/INR and PTT. Some patients also need a blood sugar or HbA1c test, a type and screen, or a pregnancy test.
There is no single list that applies to everyone, though. The blood work you need depends on your age, medical conditions, medications, the type of surgery and anesthesia, and your surgeon’s or surgical facility’s own protocol. A healthy adult having a minor procedure may need very little. Someone with diabetes, kidney disease, or heart disease having a larger operation may need much more.
This guide explains each common pre-op blood test, what it looks for, who tends to need it, when to get it done, and how to keep your surgery date on track.
Surgery coming up in Las Vegas? Sahara West Urgent Care & Wellness offers walk-in pre-op clearance with lab work, EKGs, physical exams, and medication review. Bring your surgeon’s order form and call (702) 248-0554, or book an appointment.
Common Blood Tests Before Surgery at a Glance
| Test | What it checks | Why surgeons order it | Often ordered for |
| Complete blood count (CBC) | Red blood cells, hemoglobin, white blood cells, platelets | Detects anemia, possible infection, and low platelets that affect bleeding risk | Procedures with expected blood loss, older adults, anyone with anemia or bleeding history |
| Basic metabolic panel (BMP) | Glucose, electrolytes (sodium, potassium), kidney function | Kidney function affects how medications are cleared. Electrolytes affect heart rhythm | Older adults, hypertension, kidney disease, diabetes, diuretic use |
| Comprehensive metabolic panel (CMP) | Everything in a BMP plus liver enzymes, protein, and bilirubin | Liver function affects drug metabolism and clotting | Liver disease, heavy alcohol use, certain medications |
| PT/INR and PTT | How quickly your blood clots | Flags bleeding or clotting problems | Blood thinners like warfarin, liver disease, bleeding history, some procedures |
| HbA1c and/or glucose | Average blood sugar over 2–3 months, or current blood sugar | High blood sugar raises infection and wound-healing risks | Diabetes, prediabetes, or high glucose on other tests |
| Type and screen | Blood type and antibodies | Prepares for a possible transfusion | Surgeries with a higher chance of significant blood loss |
| Pregnancy test (hCG) | Whether you are pregnant | Anesthesia, medications, and imaging carry different risks in pregnancy | People who could be pregnant |
Your surgeon’s order is the source of truth. If your surgeon or surgical center sent a lab requisition or clearance form, that document defines what you need.
Are Blood Tests Required Before Every Surgery?
No. Requirements vary, and that is by design.
Large reviews have found that most routine pre-op tests in healthy patients come back normal and rarely change the surgical plan. For this reason, several medical societies through the Choosing Wisely initiative recommend against blanket testing before low-risk procedures in patients without symptoms or risk factors. The history and physical exam usually guide which tests, if any, are worthwhile.
What typically drives the order:
- Your age. Testing becomes more common as age increases.
- Your health conditions: diabetes, kidney disease, liver disease, heart disease, lung disease, anemia, or a bleeding disorder.
- Your medications: blood thinners, diuretics, blood pressure medications, and some supplements.
- The procedure: how invasive it is, how long it takes, and how much blood loss is expected.
- The anesthesia plan: general anesthesia, sedation, or local.
- Facility policy: some hospitals and surgery centers require a standard panel regardless of risk.
Cataract surgery, for example, often requires far less testing than a joint replacement or abdominal surgery. If you aren’t sure what your procedure requires, ask your surgeon’s office for the exact list.
The Core Pre-Op Blood Tests, Explained
Complete Blood Count (CBC)
The CBC measures your red cells, hemoglobin, white cells, and platelets. Surgeons use it to spot anemia (which can reduce oxygen delivery and affect recovery), signs of infection, and low platelet counts that could raise bleeding risk. It is one of the most commonly ordered pre-op tests, and it usually doesn’t require fasting.
Basic or Comprehensive Metabolic Panel (BMP/CMP)
A metabolic panel looks at your electrolytes, kidney function, and blood sugar, and the CMP adds liver markers. Your kidneys and liver process anesthesia and other medications, and electrolyte imbalances (especially potassium) can affect heart rhythm. These panels are especially relevant if you have high blood pressure, diabetes, kidney or liver disease, or take medications that affect electrolytes.
Coagulation Tests (PT/INR and PTT)
These measure how long your blood takes to clot. They matter most if you take a blood thinner, have liver disease, or have a personal or family history of unusual bleeding. Many healthy patients don’t need them for low-risk procedures, but some surgeons and facilities include them as standard.
Important: Never stop a blood thinner on your own before blood work or surgery. Your surgeon and the prescribing doctor will give you specific instructions.
Blood Glucose and HbA1c
Blood sugar that runs high around surgery is linked to more infections and slower healing. HbA1c shows your average blood sugar over the past two to three months, so it reveals control that a single glucose reading can miss. Thresholds vary by guideline and surgeon. Many use targets in the range of about 7% to 8.5%, and the American Diabetes Association’s recent standards suggest aiming below 8% when possible. If yours runs high, an early result gives your care team time to adjust treatment rather than delay surgery at the last minute.
Type and Screen
This identifies your blood type and checks for antibodies so blood can be matched quickly if a transfusion is needed. It is generally ordered for procedures where meaningful blood loss is possible, not for minor ones. Results can take longer than routine panels, and not every clinic performs it, so confirm availability before you go.
Pregnancy Test
If there is any chance you could be pregnant, a pregnancy test is standard before anesthesia and surgery. It is usually a quick blood or urine test.
Other Tests Your Surgeon May Add
Depending on your situation, you may also be asked for a urinalysis (a urine test, not blood), liver or thyroid tests, or additional cardiac or lung evaluation. Cholesterol panels are generally not part of standard pre-op testing unless your doctor wants them for another reason.
Blood Work Is Only One Part of Pre-Op Clearance
Surgeons rarely rely on labs alone. A full pre-op clearance usually also includes:
- A physical exam and vitals: heart, lungs, blood pressure, and oxygen levels
- Medical history review: chronic conditions, past anesthesia reactions, and family history
- Medication and supplement review: what to continue, what to hold
- An EKG: a quick, painless check of heart rhythm, common for older patients or those with heart risk factors
- Sometimes a chest X-ray, depending on your health and the procedure
Blood results are interpreted alongside your history and exam, so a standalone lab draw doesn’t always satisfy a surgeon’s clearance requirement. For a walk-through of the full appointment, see What Happens During Pre-Op Clearance? or What Tests Are Done for Pre-Op?
Who Is More Likely to Need Extra Blood Work?
You are more likely to be asked for additional or repeat tests if you:
- Are older or have several chronic conditions
- Have diabetes or prediabetes
- Have kidney disease, liver disease, or heart failure
- Take blood thinners or medications that affect kidney function or electrolytes
- Have a history of anemia, easy bruising, or bleeding problems
- Are having a longer or higher-blood-loss procedure, such as major abdominal, orthopedic, or vascular surgery
Having one of these doesn’t mean your surgery is at risk. It means your team wants a clearer picture so they can plan safely.
When Should You Get Pre-Op Blood Work Done?
Timing rules differ by surgeon and facility, so use the date on your order or clearance form. General patterns:
- Many facilities want labs and the physical within about 30 days of surgery.
- Some require labs closer to the date, such as within 7 to 14 days.
- Too early and results may expire, forcing a repeat.
- Too late and there’s no time to address a problem, such as low hemoglobin or high blood sugar.
A good rule: ask your surgeon’s office for the earliest and latest acceptable dates, then book your visit toward the earlier end of that window. If your date is close, see Can I Get Pre-Op Clearance if My Surgery Is Only a Few Days Away? and How Long Is Pre-Op Before Surgery?
Short on time? Sahara West Urgent Care takes walk-ins, so you don’t need to wait weeks for a primary care opening. Call (702) 248-0554 to confirm what to bring.
Do You Need to Fast Before Pre-Op Blood Work?
It depends on which tests are ordered. Routine tests like a CBC or clotting panel generally don’t require fasting. Some glucose or cholesterol tests do. Labs differ in what they ask, which is why you’ll see conflicting advice online.
Two things to keep straight:
- Fasting for the blood draw applies only if a specific test requires it. Your order or the clinic will tell you.
- Fasting on the day of surgery (no food or drink before anesthesia) is a separate set of instructions from your surgical team.
If you are unsure, ask when you call. Showing up fasted when it wasn’t needed is harmless, but eating before a test that requires fasting can force a redraw.
How to Prepare for Your Pre-Op Blood Work Visit
Bring:
- Your surgeon’s clearance packet, order form, or lab requisition (if provided)
- The surgery date, procedure name, and surgeon’s contact or fax information
- A complete list of medications, doses, and supplements
- Photo ID and your insurance card, if applicable
- A list of allergies and past surgeries or anesthesia reactions
If you don’t have a form yet, call us with your surgeon’s name and procedure. We’ll help confirm what the office needs. For a full checklist, see What Documentation Is Needed for Pre-Op Clearance?
What If Your Blood Work Is Abnormal?
An abnormal result doesn’t automatically cancel surgery. Often it means your team needs to understand it and plan around it. For example:
- Low hemoglobin may prompt a search for the cause, and treatment may follow before surgery.
- High HbA1c or glucose may lead to medication adjustments or a short delay to improve control.
- Abnormal kidney or electrolyte values may change medication choices or anesthesia planning.
- Prolonged clotting times may lead to a medication review or further evaluation.
This is the strongest reason not to leave labs to the last minute. An early result leaves room to fix a problem without moving your surgery date.
Where to Get Pre-Op Blood Work in Las Vegas
| Option | Works best when | Trade-off |
| Your primary care office | You have a doctor and plenty of time | Appointments can take weeks to schedule |
| Standalone lab draw site | You already have a signed order and a completed physical | Draws blood only. You still need the exam and paperwork elsewhere |
| Urgent care with pre-op services | Your date is approaching or you need the exam, labs, and EKG in one visit | Confirm your surgeon accepts the clinic’s clearance and that specialized tests are available |
Sahara West Urgent Care & Wellness at 6125 W Sahara Ave, Suite 1B, Las Vegas, NV 89146, serves patients across Las Vegas, including Summerlin and Spring Valley. Our pre-op clearance service includes a physical evaluation, lab testing, EKGs, and medication review, and we can send completed results and clearance documentation to your surgeon’s office.
A few practical notes:
- Walk-ins are welcome.
- Hours: Monday to Friday, 9 AM to 8 PM; Saturday, 9 AM to 3 PM.
- X-rays (if your surgeon requests a chest X-ray) are available on Tuesdays and Thursdays, walk-ins welcome.
- Specialized tests such as a type and screen may not be available on site, so call ahead if your order includes one.
- Insurance and self-pay: we welcome a range of insurance plans and offer self-pay options. Call for details on your situation.
Having surgery with a specific specialty? See our guides for cataract surgery clearance, dental surgery clearance, and blood tests before plastic surgery.
Get your pre-op blood work done before your window closes
Call (702) 248-0554, book an appointment, or walk in at 6125 W Sahara Ave. Bring your surgeon’s paperwork and medication list, and we’ll help you get everything completed and sent to your surgical team.
Frequently Asked Questions
What blood tests are typically done before surgery?
The most common are a complete blood count (CBC), a basic or comprehensive metabolic panel, and clotting tests (PT/INR, PTT). Depending on your health and procedure, your surgeon may add HbA1c or glucose, a type and screen, and a pregnancy test.
Are blood tests required before every surgery?
No. Healthy patients having low-risk procedures may need few or no blood tests. Requirements depend on your age, health conditions, medications, the type of surgery, and your surgeon’s or facility’s policy. Your surgeon’s order form is the final word.
Do I need to fast before pre-op blood work?
Only if a specific test requires it, such as certain glucose or cholesterol tests. CBC and clotting tests generally don’t. Ask when you schedule so you know exactly what to do.
How long before surgery should I get blood work?
Many facilities want results within about 30 days of surgery, and some require them within 7 to 14 days. Follow the window on your surgeon’s paperwork, and aim for the earlier end so any problem can be addressed.
How long do pre-op blood test results take?
It depends on the test. Many routine panels come back quickly, while specialized tests such as a type and screen may take longer. Ask at your visit when to expect results and how they’ll reach your surgeon.
Can urgent care do pre-op blood work?
Yes. At Sahara West Urgent Care, pre-op clearance includes lab testing, a physical exam, EKGs, and medication review in one walk-in visit, with documentation sent to your surgical team. Confirm with your surgeon’s office that they accept an urgent care clearance.
Can I get pre-op blood work without a doctor’s order?
Bring your surgeon’s order or clearance form if you have one. If you don’t, call us with your surgeon’s name and procedure, and we’ll help confirm what’s needed.
Should I stop my blood thinners before blood work?
No, don’t stop any prescribed medication on your own. Tell the provider what you take. Your surgeon and prescribing doctor will tell you if and when to hold anything before surgery.
Do I need to repeat blood work if I had labs recently?
Possibly. Many facilities only accept results from within a set window, often around 30 days. Check with your surgeon’s office before assuming older results will count.
What happens if my pre-op blood work is abnormal?
It doesn’t automatically cancel surgery. Your team may adjust medications, change the anesthesia plan, order follow-up testing, or briefly delay surgery to improve a value. Early testing gives you the most options.
This article is for general education and isn’t medical advice. Always follow the instructions from your surgeon and anesthesia team. Sahara West Urgent Care provides non-emergency care. For chest pain, trouble breathing, or another emergency, call 911.
