CPT® Code 78120

1. Indications

The red cell volume determination procedure (CPT® Code 78120) is indicated for a variety of clinical conditions that require assessment of red blood cell volume. These indications include:

• Hypovolemia - A condition characterized by decreased blood volume, which can lead to inadequate tissue perfusion.
• Hypervolemia - An increase in blood volume that may result in fluid overload and associated complications.
• Anemia - A deficiency in the number or quality of red blood cells, leading to reduced oxygen transport in the body.
• Polycythemia - An excess of red blood cells, which can increase blood viscosity and the risk of thrombosis.
• Orthostatic Hypotension - A form of low blood pressure that occurs when standing up from sitting or lying down, often related to blood volume issues.
• Hypertension - High blood pressure that may be influenced by blood volume status.
• Heart Failure - A condition where the heart is unable to pump effectively, often associated with fluid volume imbalances.
• Shock/Acute Blood Loss - A critical condition resulting from significant blood loss, necessitating rapid assessment of blood volume.
• Dialysis - Patients undergoing dialysis may require monitoring of blood volume to manage fluid status effectively.
• Blood Transfusion - Assessment of red cell volume may be necessary before and after transfusions to ensure appropriate volume replacement.
• Volume Replacement - Evaluation of blood volume status in patients receiving volume replacement therapies.

2. Procedure

The procedure for red cell volume determination (CPT® Code 78120) involves several critical steps to ensure accurate measurement of red blood cell volume. The process begins with the collection of the patient's height and weight, which are essential for calculating the red cell volume accurately. Following this, venous access is established to facilitate blood sampling. A baseline blood sample is obtained to serve as a reference point for subsequent measurements. After the baseline sample is collected, a radiolabeled pharmaceutical, typically technetium 99m red blood cells (Tc-99m RBC), is injected into the patient. This tracer is allowed to circulate within the body for a specified period, enabling it to mix with the patient's red blood cells. Once the tracer has circulated adequately, venipuncture is performed again to draw a blood sample. This can be done as a single sample or through multiple samplings at predetermined intervals, depending on the specific requirements of the assessment. The microhematocrit is then measured from each blood sample to determine the proportion of red blood cells present. The remaining blood is subjected to centrifugation, which separates the plasma from the red blood cells, allowing for further analysis. The data obtained from the patient sample is calculated using established formulas that compare the dilution factors of the radiolabeled tracer with standardized samples. These calculations take into account the patient's height, weight, and hematocrit levels to derive an accurate assessment of red cell volume.

3. Post-Procedure

After the completion of the red cell volume determination procedure, patients may be monitored for any immediate reactions to the radiolabeled tracer, although such reactions are typically rare. The results of the test will be analyzed and interpreted by the healthcare provider, who will consider the findings in conjunction with the patient's clinical history and other diagnostic tests. Depending on the results, further evaluation or treatment may be necessary to address any identified issues related to blood volume. Patients may be advised on any specific follow-up care or additional testing that may be required based on the outcomes of the procedure. It is essential to ensure that the patient is informed about the significance of the results and any subsequent steps in their care plan.