A subpulmonic effusion is excess fluid that collects at the base of the

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

, in the space between the

pleura The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls. The inner pleura, called the visceral pleura, covers the surface of each lung and dips bet ...

and diaphragm. It is a type of

pleural effusion A pleural effusion is accumulation of excessive fluid in the pleural space, the potential space that surrounds each lung. Under normal conditions, pleural fluid is secreted by the parietal pleural capillaries at a rate of 0.6 millilitre per kilog ...

in which the fluid collects in this particular space but can be "layered out" with decubitus chest radiographs. There is minimal nature of

costophrenic angle The costodiaphragmatic recess, also called the costophrenic recess or phrenicocostal sinus, costodiaphragmatic-recess Retrieved May 2011 Imaging In anatomy, the costophrenic angles are the places where the diaphragm (''-phrenic'') meets the ribs ...

blunting usually found with larger pleural effusions. The occult nature of the effusion can be suspected indirectly on

radiograph Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...

by elevation of the right diaphragmatic border with a lateral peak and medial flattening. The presence of the

gastric The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

bubble on the left with an abnormalagm of more than 2 cm can also suggest the

diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems engin ...

. Lateral decubitus views, with the patient lying on their side, can confirm the effusion as it will layer along the lateral chest wall. Subpulmonic space refers to the space below the lungs in which the subpulmonic fluid fills. Subpulmonic fluid is common particularly in trauma cases where the apparent

hemidiaphragm The thoracic diaphragm, or simply the diaphragm ( grc, διάφραγμα, diáphragma, partition), is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm is the mo ...

appears defeated and the apex is displaced laterally.

References

{{reflist Anatomy Lung disorders