14.1  Diagnostic methods

In Study Session 13 you learnt about the clinical symptoms of TB. They are a cough for two or more weeks, spitting up blood in the sputum, weight loss, fever or night sweats for three or more weeks, fatigue, and loss of appetite, chest pains or difficulty breathing.

  • If a person comes to you complaining of a persistent cough that has lasted for over two weeks and they are also producing whitish sputum, what should you do?

    Sputum is a secretion coughed up from the lungs and expectorated (expelled) through the mouth.

  • This person is showing symptoms that are consistent with an active TB infection. You should obtain sputum samples from this individual to send for sputum examination to confirm the diagnosis.

Remember, taking a history from the person you suspect of having TB will allow you to determine if they need to be referred for a sputum examination.

If you ask the right questions and make the right observations, you will be able to identify those individuals who you suspect of having TB. What to look for depends on the type of TB involved. The key symptoms of both forms of TB are summarised in Box 14.1.

Box 14.1  Key symptoms of both forms of TB

Active Pulmonary TB disease (PTB)

A low grade fever is defined as a slight increase in body temperature that does not exceed 38.5oC.

Pulmonary TB has several manifestations. The most common and obvious one is a persistent cough that lasts for two weeks or more which is usually accompanied with the production of whitish sputum.

Other key symptoms are spitting of blood, weight loss, low grade fever, loss of appetite, night sweating, chest pain and shortness of breath or difficulty in breathing. Any person with persistent cough of two or more weeks (with or without any of these other symptoms) should be suspected of having TB and you should refer them for a sputum examination.

Extra-Pulmonary TB disease (EPTB)

Persons with one or more of these symptoms should be investigated for extra-pulmonary TB and referred urgently to a health facility.

The symptoms of EPTB will vary depending on the organ affected (this was summarised in the previous Study Session in Table 13.2), but they can include: back pain, swelling on the spine, long-lasting bone infection, painful joint swelling (usually affecting one joint), painful urination, blood in urine, frequent urination, hoarseness of voice, pain on swallowing, headache, fever, neck stiffness, vomiting, irritability, convulsions, swelling of the lymph node with draining pus and long-lasting ulcers resistant to antibiotic treatment.

We will now describe in more detail different methods used to diagnose tuberculosis and other procedures that are used to diagnose extra-pulmonary tuberculosis (EPTB). Diagnosis of tuberculosis is made at health centres and hospitals, but you will make a vital contribution by identifying those individuals who may be infected with TB and referring them for investigation. Part of your role is to provide information and counsel those who are about to undergo diagnostic investigation and treatment.

Learning Outcomes for Study Session 14

14.1.1  Microscopic examination of sputum smears