Font Size
A
A
A
2
...

Complete Blood Count (CBC) (cont.)

Complete Blood Count Procedure

The complete blood count may be done in many different health care settings including doctors' offices, clinics, urgent care facilities, emergency rooms, hospitals, and outpatient medical laboratories. It is typically done upon an order by a physician for a variety of reasons.

The complete blood count test is performed by drawing a few milliliters (one to two teaspoons) of blood from a vein. Most commonly, the sample is obtained from a vein that is visible from the skin, such as a vein on the back of the hand or the inner angle of the elbow (antecubital fossa).

A tourniquet is usually applied to the area proximal to the vein (closer to the center of the body than the vein itself). This technique will make the vein more visible and plump by limiting the blood from the vein going back toward the heart. The tourniquet is only applied for a brief period of time (a few minutes at the most) and it is removed as soon as blood is drawn.

The skin overlying the vein is cleaned using an alcohol pad, and then a needle is inserted through the area of cleansed skin into the vein below where the tourniquet is applied. The blood is then pulled from the vein via the needle by gently pulling the plunger on the syringe or by a connection of the needle to a special vacuum vial that collects the blood.

This sample is then taken to the laboratory for analysis, and the complete blood count results may be available within hours after collection. Prompt delivery of the blood sample to the laboratory for analysis is important. A sample that is not delivered in a timely manner may yield inaccurate results.

Medically Reviewed by a Doctor on 5/28/2014

Must Read Articles Related to Complete Blood Count (CBC)

Acute Kidney Failure
Acute Kidney Failure Kidney failure, or the ability of the kidneys to filter water and waste is caused by prerenal, postrenal, or renal problems with the kidney(s). Symptoms of kidn...learn more >>
Acute Respiratory Distress Syndrome
Acute Respiratory Distress Syndrome Acute respiratory distress syndrome (ARDS) is a severe lung condition caused by trauma, sepsis, pancreatitis, aspiration, drug overdose, and massive blood trans...learn more >>
Allergic Reaction
Allergic Reaction An allergic reaction is an overreaction to a harmless substance. Symptoms and signs of an allergic reaction include hives, rashes, swelling, itching, wheezing, ...learn more >>




Read What Your Physician is Reading on Medscape

Preoperative Testing »

Medical consultants are generally asked to assess preoperative risk in most patients who are to undergo surgery.

Read More on Medscape Reference »


Medical Dictionary