Complete Blood Count (CBC)

A complete blood count (CBC) is a common blood test that measures the cells circulating in your blood, including red blood cells, white blood cells, and platelets. It gives your health care team important information about your overall health and can help detect a wide range of conditions, from anemia and infections to blood disorders.

The acid-fast stain test is a laboratory examination that looks for acid-fast bacteria in your sputum. Acid-fast bacteria have a unique waxy coating that makes them resistant to standard staining methods. The most common acid-fast bacterium is Mycobacterium tuberculosis, which causes tuberculosis (TB). This test uses special dyes and procedures to make these bacteria visible under a microscope.

Your doctor may order a CBC as part of a routine checkup, before surgery, or if you have symptoms such as fatigue, weakness, fever, unusual bruising, or unexplained bleeding. The results help screen for conditions like anemia, infection, and blood cancers, and can also be used to monitor an ongoing illness or check how well a treatment is working.

Your healthcare provider ordered this test because you have symptoms that could indicate tuberculosis, such as a persistent cough lasting more than three weeks, coughing up blood, fever, night sweats, or unexplained weight loss. This test helps determine if you have an active TB infection in your lungs.

A health care professional will clean the skin on the inside of your elbow or the back of your hand, then use a small needle to draw a sample of blood into a tube. The process usually takes less than five minutes. Afterward, a bandage is placed on the site and the sample is sent to a laboratory for analysis. No special preparation is needed for this test.

You will need to provide a sputum sample, which is mucus that comes from deep inside your lungs when you cough. For this test (the second specimen), you will be asked to cough deeply and spit into a special sterile container. It is important to produce sputum from your lungs, not saliva. You may be asked to rinse your mouth with water before providing the sample to reduce contamination. The sample is then sent to a laboratory where it is treated with special stains and examined under a microscope.

This test is very safe and carries few risks. You may feel a quick sting when the needle goes in, and the site may be slightly sore or bruised for a day or two. Serious complications such as excessive bleeding, infection, or feeling faint are rare. If you notice ongoing bleeding, increasing pain, or swelling at the puncture site, contact your health care provider.

This test carries minimal risk. The main discomfort is the effort required to produce a proper sputum sample from the lungs. If you have difficulty producing sputum, your healthcare provider may recommend other collection methods.