Preparing for surgery: pre-op blood work

Preparing for surgery: pre-op blood work

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It’s important to be as healthy as possible at the time of surgery, which is why a pre-operative appointment for blood work is a standard practice. Some blood tests prior to surgery are routine for all patients, while others may only be done if the patient has a history of certain medical conditions.

Your surgeon will go over your medical history with you during your appointment, but you may also need to see an anesthesiologist at the hospital’s pre-op clinic prior to surgery. Your pre-op blood work is most commonly done at this time, typically a few days to a week before surgery. At that time, you should also receive any special instructions about stopping certain medications, which medications to take on the day of surgery, any special skin prep solution to use, and not eating or drinking prior to surgery.

Here’s an overview of the most common pre-op tests we order.

Complete Blood Count (CBC) Panel

A CBC panel is done for all scheduled, non-emergency surgeries and checks four main components.

  • White blood cells, which are your infection-fighting cells. If the count is high, that typically means there’s an infection in your body somewhere. That could mean a urinary tract infection, skin infection, or abscessed tooth, for example. Sometimes the patient isn’t even aware of the infection. If there is an infection, you’ll be treated with antibiotics to clear up the infection prior to surgery.
  • Hemoglobin and hematocrit are two separate measures of your red blood cells. Hemoglobin carries oxygen to your tissues, which is important for healing, so it’s important to have a normal level prior to surgery. Hematocrit measures the volume of red blood cells compared to total blood volume. Low hemoglobin and hematocrit typically means a patient has anemia, often due to an iron deficiency. Some blood loss occurs in any surgery, so it’s important for a patient to start with adequate blood levels. If your pre-op blood work shows anemia, you may be prescribed iron pills or other medications to help increase red blood cells before surgery.
  • Platelets are important for clotting. Any wound, including a surgical incision, needs adequate platelets to form a clot and heal the wound. If platelets are too low, a platelet transfusion can be done to increase the level prior to surgery to ensure appropriate clotting. Sometimes high platelets can be another sign of infection somewhere in the body, and low platelets often indicate liver problems, such as hepatitis or cirrhosis.

Complete Metabolic Panel (CMP)

Also known as a “chemistry” or “chem panel,” the CMP includes what most people think of as electrolytes, including sodium, potassium, calcium, and many others. These different electrolytes have different roles in the body, and an imbalance can indicate that something is going on somewhere in the body. If an electrolyte is too low, it can usually be replaced. If it’s too high, an electrolyte with an opposing function is often given to help balance the body.

Coagulation Labs

Coagulation labs include PT and PTT/INR and measure your body’s ability to stop bleeding. These make sure you don’t have an unusually high bleeding tendency. If you take blood thinners for another medical condition, it’s important to discuss that with your doctor well in advance of your surgery. Common blood thinners include Coumadin, Warfarin, Eliquis, Pradaxa, and Xarelto. It’s generally recommended to stop taking blood thinners prior to surgery, but the specific type of medication and the condition it’s treating will impact how long before surgery you’re asked to stop taking it.


A urinalysis is another test used to look at possible infection, as you do not want to undergo surgery with an infection present. If an infection is already present in your body, that bacteria will travel to the surgical site as well.

Hemoglobin A1C

This test measures glucose levels over the past several weeks and helps determine whether a person’s diabetes is well controlled. Typically, A1C should be lower than 8 prior to a scheduled surgery. Uncontrolled diabetes can increase the risk of infection and complicate the wound healing process. It’s not unusual in pre-op blood work to identify someone who is diabetic and didn’t know it. If the A1C is too high, a patient will be referred back to their primary care physician to help control the diabetes before surgery.

Chest X-Ray

Many hospitals require a chest x-ray prior to surgery to scan for public health issues like tuberculosis (TB). In older patients, the chest x-ray can also be used to show possible pneumonia, collapsed air sacs in the lungs, an enlarged heart, or hardening of the arteries, all of which can increase anesthetic risk.


An EKG, or electrocardiogram, measures the electrical activity of your heart. It’s typically done for patients over the age of 35 unless younger patients have a cardiac history or another reason to require an EKG. The test can help ensure there are no underlying cardiac issues, such as an abnormal heart rhythm or a prior heart attack the patient didn’t know about. If the EKG shows anything of concern, the patient may be referred back to their primary care physician and/or a cardiologist prior to surgery.

If you have questions about the pre-op process or want to discuss whether an existing medical condition affects your ability to have surgery, contact the Oklahoma Shoulder Center today for a consultation appointment.