Is a small amount of pleural effusion serious?

In the middle of the visceral and parietal pleura is an inconspicuous pleural cavity. Under normal circumstances, the pleural cavity contains trace amounts of fluid, which keeps the two layers of pleura moist during breathing, thereby reducing friction. Its production and absorption are often in a dynamic balance. Any pathological condition that delays its production or reduces its absorption will result in pleural effusion.

1. Clinical manifestations

1. Cough and chest pain are often dry coughs accompanied by stabbing pain in the chest. Chest pain worsens when coughing or taking a deep breath.

2. Difficulty breathing: When there is a small amount of effusion, the symptoms are not obvious, or there is a slight feeling of chest tightness; when there is a large amount of effusion, there is obvious difficulty breathing. At this time, chest pain may ease.

3. Systemic symptoms depend on the cause of pleural effusion.

4. Physical signs: There may be pleural friction sound when there is a small amount of effusion. Typical signs of effusion include fullness of the chest on the affected side, weakened respiratory movement, dullness on percussion, weakened or disappeared vocal fremitus and breath sounds. In moderate amount of effusion, bronchial breath sounds can sometimes be heard at the upper edge of the dullness on percussion. In large amount of effusion, the trachea is shifted to the healthy side.

2. Diagnostic Basis

1. Chest tightness, chest pain, and shortness of breath.

2. When the amount of pleural effusion is small, there may be no positive signs. When the amount of effusion is large, the respiratory movement of the affected side is weakened, the vocal fremitus disappears, percussion is dull or solid, the breath sounds are weakened or disappear, and the trachea, mediastinum, and heart move toward the healthy side.

3. When the amount of pleural effusion is 0.3 to 0.5 L, the X-ray only shows a blunting of the costophrenic angle; more effusion will show an effusion shadow with an arc-shaped upper edge extending outward and upward. When lying flat, the accumulated fluid disperses, reducing the transparency of the entire lung field. In hydropneumothorax, there is a fluid level in the effusion. When a large amount of fluid accumulates, the entire affected side becomes dark and the mediastinum is pushed toward the healthy side. The effusion often has smooth and full edges and is confined to the interlobar space or between the lung and the diaphragm. Ultrasound examination is helpful for diagnosis.

4. B-ultrasound can detect masses covered by pleural effusion and assist in the positioning of thoracentesis. CT examination can determine whether the pleural fluid is exudate, blood or pus based on the different densities of the pleural fluid. It can also show the mediastinum, paratracheal lymph nodes, lung masses, pleural mesothelioma and intrathoracic metastatic tumors. CT examination of pleural lesions has high sensitivity and density resolution. It is easier to detect small amounts of fluid that are difficult to show on plain X-ray films.

5. Thoracentesis is performed to extract fluid, and pleural fluid examinations are performed for routine, biochemical, immunological and cytological examinations.

The above evidence can confirm that it is exudate or transudate, which is helpful for diagnosing the cause.

Pleural effusion is a key disease of the chest and the whole body, so it is particularly important to find the cause and treat it. Transudate can often be absorbed and removed after the cause is changed. Therefore, a small amount of pleural effusion is not serious and there is no need to worry too much.