Pneumonia - Diagnosis

Diagnosis

Diagnostic Difficulties in Community-Acquired Pneumonia (CAP). It is important to determine whether the cause of CAP is a bacterium, atypical bacterium, or virus, because they require different treatments. In children, for example, S. pneumoniae is the most common cause of pneumonia, but respiratory syncytial virus may also cause the disease. Although symptoms may differ, they often overlap, which can make it difficult to identify the organism by symptoms alone. The cause of CAP is found in only about half of cases.

Nevertheless, in many cases of mild-to-moderate CAP, the physician is able to diagnose and treat pneumonia based solely on a medical history and physical examination.

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Diagnostic Difficulties with Hospital-Acquired (Nosocomial) Pneumonia. Diagnosing pneumonia is particularly difficult in hospitalized patients for a number of reasons:

• Many hospitalized patients have similar symptoms, including fever or abnormal x-rays.
• In hospitalized patients, sputum or blood tests often show bacteria or other organisms, but such agents do not necessarily indicate pneumonia.

Medical and Personal History

The patient's history is an important part of making a pneumonia diagnosis. Patients should report any of the following:

• Alcohol or drug abuse
• Exposure to people with pneumonia or other respiratory illnesses (such as tuberculosis)
• History of smoking
• Occupational risks
• Recent or chronic respiratory infection
• Recent antibiotic therapy
• Recent outpatient wound care
• Home infusion therapy or dialysis
• Recent travel
• Exposure to birds, bats, or other animals

Physical Examination

Use of the Stethoscope. The most important diagnostic tool for pneumonia is the stethoscope. Sounds in the chest that may indicate pneumonia include:

• Rales, a bubbling or crackling sound. Rales on one side of the chest or that are heard while the patient is lying down strongly suggest pneumonia.
• Rhonchi, abnormal rumblings indicating that there is sputum in the large airways.
• A dull thud. The physician will use a test called percussion, in which the chest is tapped lightly. A dull thud, instead of a hollow drum-like sound, indicates certain conditions that suggest pneumonia. These conditions include consolidation (in which the lung becomes firm and inelastic) and pleural effusion (fluid build-up in the space between the lungs and the lining around it).