Sputum for acid fast bacilli
(AFB)

Sample type

• Sputum ( usually three sputum samples are collected early in the morning on different days. )

Uses

• AFB tests are most often used to diagnose an active tuberculosis (TB) infection. They may also be used to help diagnose other types of AFB infections. These include: Leprosy, a once feared, but now a rare and easily treatable disease that affects the nerves, eyes, and skin. Skin often becomes red and flaky, with loss of feeling.

Precautions

• To collect a sputum sample, you should do the following:

  1. Brush your teeth and rinse your mouth without using antiseptic mouthwash.

  2. Take a couple of long, deep breaths.

  3. Breathe deeply again and cough hard until sputum comes up.

  4. Spit out the sputum into the sample cup.

  5. Keep coughing up sputum until the cup is filled to the marker, which is approximately 1 teaspoon.

  6. Screw on the cup lid, and wash and dry the outside of it.

  7. Write your name, your date of birth, and the date of collection on the cup label.

Take the sample to the clinic or laboratory, as instructed. The sample can be refrigerated for up to 24 hours if needed. Don’t freeze it or store it at room temperature.

Interfering factors

• The night before the test, drink lots of fluids, such as water or tea, to help your body make more sputum overnight.

• Collecting your sputum in the morning makes the test more accurate. More bacteria are present first thing in the morning.

• If you still cannot cough up sputum, your doctor will do a bronchoscopy to collect sputum directly from your lungs.

Pre analytical errors

1) Inappropriate handling of the sputum

Corrective action

1) The sample can be refrigerated for up to 24 hours if needed. Don’t freeze it or store it at room temperature and keep it in specific container because the sample may be cause infection .

Post analytical errors

1) failure to report test results, delay in reporting, incorrect calculation, critical results not reported or delayed, and results sent to the wrong patient.

Corrective action

1) Suggesting strong information report system .

Reference ranges

• Positive or Negative