Hemothorax tends to occur following blunt or penetrating trauma to the thorax or thoracoabdominal area. It may also follow thoracic surgery, or may be spontaneous. Chest pain, dyspnea, and tachypnea are common presenting features. Other symptoms of hemothorax are dependent on the mechanism of injury, but may include:

- Cyanosis

- Decreased or absent breath sounds on affected side

- Tracheal deviation to unaffected side

- Dull resonance on percussion

- Unequal chest rise

- Tachycardia

- Hypotension

- Pale, cool, clammy skin

- Possible subcutaneous emphysema

- Narrowing pulse pressure

Although multiple definitions exist, a tension pneumothorax is generally considered to be present when a pneumothorax (primary spontaneous, secondary spontaneous, or traumatic) leads to significant impairment of respiration and/or blood circulation. Tension pneumothorax tends to occur in clinical situations such as ventilation, resuscitation, trauma, or in patients with lung disease.

The most common findings in people with tension pneumothorax are chest pain and respiratory distress, often with an increased heart rate (tachycardia) and rapid breathing (tachypnea) in the initial stages. Other findings may include quieter breath sounds on one side of the chest, low oxygen levels and blood pressure, and displacement of the trachea away from the affected side. Rarely, there may be cyanosis (bluish discoloration of the skin due to low oxygen levels), altered level of consciousness, a hyperresonant percussion note on examination of the affected side with reduced expansion and decreased movement, pain in the epigastrium (upper abdomen), displacement of the apex beat (heart impulse), and resonant sound when tapping the sternum. This is a medical emergency and may require immediate treatment without further investigations (see below).

Tension pneumothorax may also occur in someone who is receiving mechanical ventilation, in which case it may be difficult to spot as the person is typically receiving sedation; it is often noted because of a sudden deterioration in condition. Recent studies have shown that the development of tension features may not always be as rapid as previously thought. Deviation of the trachea to one side and the presence of raised jugular venous pressure (distended neck veins) are not reliable as clinical signs.

A primary spontaneous pneumothorax (PSP) tends to occur in a young adult without underlying lung problems, and usually causes limited symptoms. Chest pain and sometimes mild breathlessness are the usual predominant presenting features. People who are affected by PSPs are often unaware of potential danger and may wait several days before seeking medical attention. PSPs more commonly occur during changes in atmospheric pressure, explaining to some extent why episodes of pneumothorax may happen in clusters. It is rare for PSPs to cause tension pneumothoraces.

Secondary spontaneous pneumothoraces (SSPs), by definition, occur in individuals with significant underlying lung disease. Symptoms in SSPs tend to be more severe than in PSPs, as the unaffected lungs are generally unable to replace the loss of function in the affected lungs. Hypoxemia (decreased blood-oxygen levels) is usually present and may be observed as cyanosis (blue discoloration of the lips and skin). Hypercapnia (accumulation of carbon dioxide in the blood) is sometimes encountered; this may cause confusion and – if very severe – may result in comas. The sudden onset of breathlessness in someone with chronic obstructive pulmonary disease (COPD), cystic fibrosis, or other serious lung diseases should therefore prompt investigations to identify the possibility of a pneumothorax.

Traumatic pneumothorax most commonly occurs when the chest wall is pierced, such as when a stab wound or gunshot wound allows air to enter the pleural space, or because some other mechanical injury to the lung compromises the integrity of the involved structures. Traumatic pneumothoraces have been found to occur in up to half of all cases of chest trauma, with only rib fractures being more common in this group. The pneumothorax can be occult (not readily apparent) in half of these cases, but may enlarge - particularly if mechanical ventilation is required. They are also encountered in patients already receiving mechanical ventilation for some other reason.

Upon physical examination, breath sounds (heard with a stethoscope) may be diminished on the affected side, partly because air in the pleural space dampens the transmission of sound. Measures of the conduction of vocal vibrations to the surface of the chest may be altered. Percussion of the chest may be perceived as hyperresonant (like a booming drum), and vocal resonance and tactile fremitus can both be noticeably decreased. Importantly, the volume of the pneumothorax can show limited correlation with the intensity of the symptoms experienced by the victim, and physical signs may not be apparent if the pneumothorax is relatively small.

A hemothorax is a type of pleural effusion in which blood accumulates in the pleural cavity. This excess fluid can interfere with normal breathing by limiting the expansion of the lungs. The term is from "" + "thorax".

Presentation may be subtle; people with mild contusion may have no symptoms at all. However, pulmonary contusion is frequently associated with signs (objective indications) and symptoms (subjective states), including those indicative of the lung injury itself and of accompanying injuries. Because gas exchange is impaired, signs of low blood oxygen saturation, such as low concentrations of oxygen in arterial blood gas and cyanosis (bluish color of the skin and mucous membranes) are commonly associated. Dyspnea (painful breathing or difficulty breathing) is commonly seen, and tolerance for exercise may be lowered. Rapid breathing and a rapid heart rate are other signs. With more severe contusions, breath sounds heard through a stethoscope may be decreased, or rales (an abnormal crackling sound in the chest accompanying breathing) may be present. People with severe contusions may have bronchorrhea (the production of watery sputum). Wheezing and coughing are other signs. Coughing up blood or bloody sputum is present in up to half of cases. Cardiac output (the volume of blood pumped by the heart) may be reduced, and hypotension (low blood pressure) is frequently present. The area of the chest wall near the contusion may be tender or painful due to associated chest wall injury.

Signs and symptoms take time to develop, and as many as half of cases are asymptomatic at the initial presentation. The more severe the injury, the more quickly symptoms become apparent. In severe cases, symptoms may occur as quickly as three or four hours after the trauma. Hypoxemia (low oxygen concentration in the arterial blood) typically becomes progressively worse over 24–48 hours after injury. In general, pulmonary contusion tends to worsen slowly over a few days, but it may also cause rapid deterioration or death if untreated.

Pulmonary contusion and laceration are injuries to the lung tissue. Pulmonary laceration, in which lung tissue is torn or cut, differs from pulmonary contusion in that the former involves disruption of the macroscopic architecture of the lung, while the latter does not. When lacerations fill with blood, the result is pulmonary hematoma, a collection of blood within the lung tissue. Contusion involves hemorrhage in the alveoli (tiny air-filled sacs responsible for absorbing oxygen), but a hematoma is a discrete clot of blood not interspersed with lung tissue. A collapsed lung can result when the pleural cavity (the space outside the lung) accumulates blood (hemothorax) or air (pneumothorax) or both (hemopneumothorax). These conditions do not inherently involve damage to the lung tissue itself, but they may be associated with it. Injuries to the chest wall are also distinct from but may be associated with lung injuries. Chest wall injuries include rib fractures and flail chest, in which multiple ribs are broken so that a segment of the ribcage is detached from the rest of the chest wall and moves independently.

A pulmonary laceration is a chest injury in which lung tissue is torn or cut. An injury that is potentially more serious than pulmonary contusion, pulmonary laceration involves disruption of the architecture of the lung, while pulmonary contusion does not. Pulmonary laceration is commonly caused by penetrating trauma but may also result from forces involved in blunt trauma such as shear stress. A cavity filled with blood, air, or both can form. The injury is diagnosed when collections of air or fluid are found on a CT scan of the chest. Surgery may be required to stitch the laceration, to drain blood, or even to remove injured parts of the lung. The injury commonly heals quickly with few problems if it is given proper treatment; however it may be associated with scarring of the lung or other complications.

Hemopneumothorax, or haemopneumothorax, is a medical term describing the combination of two conditions: pneumothorax, or air in the chest cavity, and hemothorax (also called hæmothorax), or blood in the chest cavity.

A hemothorax, pneumothorax or both can occur if the chest wall is punctured. To understand the ramifications of this it is important to have an understanding of the role of the pleural space. The pleural space is located anatomically between the visceral membrane, which is firmly attached to the lungs, and the parietal membrane which is firmly attached to the chest wall (a.k.a. ribcage and intercostal muscles, muscles between the ribs). The pleural space contains pleural fluid. This fluid holds the two membranes together by surface tension, as much as a drop of water between two sheets of glass prevents them from separating. Because of this, when the intercostal muscles move the ribcage outward, the lungs are pulled out as well, dropping the pressure in the lungs and pulling air into the bronchi, when we 'breathe in'. The pleural space is maintained in a constant state of negative pressure (in comparison to atmospheric pressure).

In 1988, a group led by R.B. Wagner divided pulmonary lacerations into four types based on the manner in which the person was injured and indications found on a CT scan. In type 1 lacerations, which occur in the mid lung area, the air-filled lung bursts as a result of sudden compression of the chest. Also called compression-rupture lacerations, type 1 are the most common type and usually occur in a central location of the lung. They tend to be large, ranging in size from 2–8 cm. The shearing stress in type 2 results when the lower chest is suddenly compressed and the lower lung is suddenly moved across the vertebral bodies. Type 2, also called compression-shear, tends to occur near the spine and have an elongated shape. Type 2 lacerations usually occur in younger people with more flexible chests. Type 3, which are caused by punctures from fractured ribs, occur in the area near the chest wall underlying the broken rib. Also called rib penetration lacerations, type 3 lacerations tend to be small and accompanied by pneumothorax. Commonly, more than one type 3 laceration will occur. Type 4, also called adhesion tears, occur in cases where a pleuropulmonary adhesion had formed prior to the injury, in which the chest wall is suddenly fractured or pushed inwards. They occur in the subpleural area and result from shearing forces at sites of transpleural adhesion.

If the chest wall, and thus the pleural space, is punctured, blood, air or both can enter the pleural space. Air/blood rushes into the space in order to equalise the pressure with that of the atmosphere. As a result, the fluid is disrupted and the two membranes no longer adhere to each other. When the rib cage moves out, it no longer pulls the lungs with it. Thus the lungs cannot expand, the pressure in the lungs never drops and no air is pulled into the bronchi. Respiration is not possible. The affected lung, which has a great deal of elastic tissue, shrivels in what is referred to as a collapsed lung.

Fibrothorax is diffuse fibrosis of the pleural space surrounding the lungs. It can have several causes including hemothorax, pleural effusion and tuberculosis. It may also be induced by exposure to certain substances, as with asbestos-induced diffuse pleural fibrosis. Idiopathic fibrothorax may also occur.

In fibrothorax, scar tissue is formed around the visceral pleura following inflammation due to pleural effusion or other pathology. The scar tissue lies in a sheet between the pleura, then fuses with the parietal pleura and the chest wall. Over time, generally the course of years, the fibrotic scar tissue slowly tightens, which results in the contraction of the entire hemithorax, and leaves the ribs immobilized. Within the chest, the lung is compressed and unable to expand, making it vulnerable to collapse. At the microscopic level, the scar tissue is composed of collagen fibers deposited in a basket weave pattern. The treatment for fibrothorax is decortication, the surgical removal of the fibrous layer of scar tissue. However, since many of the diseases and conditions resulting in fibrothorax are treatable, prevention remains the preferred method of managing fibrothorax.

Hydrothorax is a type of pleural effusion in which transudate accumulates in the pleural cavity. This condition is most likely to develop secondary to congestive heart failure, following an increase in hydrostatic pressure within the lungs. More rarely, hydrothorax can develop in patients with cirrhosis or ascites. Hepatic hydrothorax is often difficult to manage in end-stage liver failure and often fails to respond to therapy.

Pleural effusions may also develop following the accumulation of other fluids within the pleural cavity; if the fluid is blood it is known as hemothorax (as in major chest injuries), if the fluid is pus it is known as pyothorax (resulting from chest infections), and if the fluid is lymph it is known as chylothorax (resulting from rupture of the thoracic duct).

A pleural effusion is excess fluid that accumulates in the pleural cavity, the fluid-filled space that surrounds the lungs. This excess can impair breathing by limiting the expansion of the lungs. Various kinds of pleural effusion, depending on the nature of the fluid and what caused its entry into the pleural space, are hydrothorax (serous fluid), hemothorax (blood), urinothorax (urine), chylothorax (chyle), or pyothorax (pus). A pneumothorax is the accumulation of air in the pleural space, and is commonly called a "collapsed lung."

Various methods can be used to classify pleural fluid.

By the origin of the fluid:

- Serous fluid (hydrothorax)

- Blood (haemothorax)

- Chyle (chylothorax)

- Pus (pyothorax or empyema)

- Urine (urinothorax)

By pathophysiology:

- Transudative pleural effusion

- Exudative pleural effusion

By the underlying cause (see next section).

Onset of lung collapse is less than 72 hours after menstruation. Typically, it occurs in women aged 30–40 years, but has been diagnosed in young girls as early as 10 years of age and post menopausal women (exclusively in women of menstrual age) most with a history of pelvic endometriosis.

Catamenial pneumothorax is the most common form of thoracic endometriosis syndrome, which also includes catamenial hemothorax, catamenial hemoptysis, catamenial hemopneumothorax and endometriosis lung nodules, as well as some exceptional presentations.

Breath sounds on the side of the rupture may be diminished, respiratory distress may be present, and the chest or abdomen may be painful. Orthopnea, dyspnea which occurs when lying flat, may also occur, and coughing is another sign. In people with herniation of abdominal organs, signs of intestinal blockage or sepsis in the abdomen may be present. Bowel sounds may be heard in the chest, and shoulder or epigastric pain may be present. When the injury is not noticed right away, the main symptoms are those that indicate bowel obstruction.

Exposure to asbestos fibers reach the pleura of the lungs through the lymphatic channels or blood stream. Historically, ship builders and insulation workers are at greater risk.

Affected persons are usually asymptomatic.

On radiological studies, pleural plaques are visualized using conventional chest x-rays and computed tomography scans (CT scans). The locations of the lesions are mostly in the parietal pleura of the lungs, especially in the posterior/lateral regions of the thorax, diaphragmatic domes, and lung fissures. In some cases, calcifications are also evident, especially with CT scans.

No treatment is required since pleural plaques are benign. However, studies have demonstrated that pleural plaques are an independent risk factor for developing bronchogenic carcinoma and/or mesothelioma.

Initial formation of a pleural effusion causes retraction of the lung lobules and widening of the fissures. This widening of the fissures allows the accumulation of liquid and the formation of a well-defined lenticular lesion.

Affected persons usually present with signs of systemic fluid overload due to conditions such as congestive heart failure (CHF), cirrhosis or renal insufficiency.

On radiological studies, a pleural pseudotumor is visualized as a biconcave or lenticular lesion using conventional chest x-rays and CT scans. The lesion is most commonly located in the minor (horizontal) fissure of the lung. A pleural pseudotumor is also associated with the presence of dependent pleural effusions.

Diuretics causes regression of the lesion.

Treatment of hydrothorax is difficult for several reasons. The underlying condition needs to be corrected; however, often the source of the hydrothorax is end stage liver disease and correctable only by transplant. Chest tube placement should not occur. Other measures such as a TIPS procedure are more effective as they treat the cause of the hydrothorax, but have complications such as worsened hepatic encephalopathy.

The defining symptom of pleurisy is a sudden sharp, stabbing, burning or dull pain in the right or left side of the chest during breathing, especially when one inhales and exhales. It feels worse with deep breathing, coughing, sneezing, or laughing. The pain may stay in one place, or it may spread to the shoulder or back. Sometimes, it becomes a fairly constant dull ache.

Depending on its cause, pleuritic chest pain may be accompanied by other symptoms:

- Dry cough

- Fever and chills

- Rapid, shallow breathing

- Shortness of breath

- Fast heart rate

- Sore throat followed by pain and swelling in the joints

Diaphragmatic rupture (also called diaphragmatic injury or tear) is a tear of the diaphragm, the muscle across the bottom of the ribcage that plays a crucial role in respiration. Most commonly, acquired diaphragmatic tears result from physical trauma. Diaphragmatic rupture can result from blunt or penetrating trauma and occurs in about 5% of cases of severe blunt trauma to the trunk.

Diagnostic techniques include X-ray, computed tomography, and surgical techniques such as laparotomy. Diagnosis is often difficult because signs may not show up on X-ray, or signs that do show up appear similar to other conditions. Signs and symptoms included chest and abdominal pain, difficulty breathing, and decreased lung sounds. When a tear is discovered, surgery is needed to repair it.

Injuries to the diaphragm are usually accompanied by other injuries, and they indicate that more severe injury may have occurred. The outcome often depends more on associated injuries than on the diaphragmatic injury itself. Since the pressure is higher in the abdominal cavity than the chest cavity, rupture of the diaphragm is almost always associated with herniation of abdominal organs into the chest cavity, which is called a traumatic diaphragmatic hernia. This herniation can interfere with breathing, and blood supply can be cut off to organs that herniate through the diaphragm, damaging them.

Air or gas also can build up in the pleural space. This is called a pneumothorax. It can result from acute lung injury or a lung disease like emphysema. Lung procedures, like surgery, drainage of fluid with a needle, examination of the lung from the inside with a light and a camera, or mechanical ventilation, also can cause a pneumothorax.

The most common symptom is sudden pain in one side of the lung and shortness of breath. A pneumothorax also can put pressure on the lung and cause it to collapse.

If the pneumothorax is small, it may go away on its own. If large, a chest tube is placed through the skin and chest wall into the pleural space to remove the air.

Thoracic endometriosis is characterised by onset of the following clinical situations within 24 hours prior to and 72 hours after onset of menses.

- Catamenial pneumothorax: this is the most common clinical manifestation, present in 80% of cases. Catamenial pneumothorax is defined as a recurrent pneumothorax that occurs within the first 72 hours after menstruation. It may not necessarily occur with every menstrual cycle and in most cases is one-sided and right side. There are particular cases of catamenial pneumothorax on the left side, and on very rare occasions there may be a bilateral catamenial pneumothorax. Symptoms are the same as for any other pneumothorax: chest pain, cough and breathlessness. Symptoms are usually mild but there may be severe presentations.

- Catamenial hemothorax: this is a rare manifestation of thoracic endometriosis, occurring in 14% of cases. Almost always, the right side is involved but has reported one case of a bilateral catamenial hemothorax. The most common presenting symptoms are nonspecific and include cough, chest pain and shortness of breath. In some cases, signs may mimic pulmonary embolism. The quantity of blood loss varies, but severe anemia is possible. In almost all cases, chest x-ray shows the presence of pleural effusion without specific characteristics. A CT scan may show additional features such as nodular lesions of the pleura, multiloculated effusions, or bulky pleural masses.

- Cyclic haemoptysis: haemoptysis during menstruation is extremely rare, with about 30 case reports in medical literature. Currently, there have been no reports of massive haemoptysis or death. Cyclic haemoptysis is a sign of pulmonary parenchymal endometriosis; ectopic endometrial tissue in the lung responds to cyclical hormonal variation, bleeding along with the normal endometrium located in the uterus.

- Pulmonary nodules: nodules are common radiological features in patients with thoracic endometriosis; most cases are associated with catamenial haemoptysis.

Apart from the previously mentioned clinical manifestations, the patient may suffer from dysmenorrhoea and irregular menses.

Pneumothorax and haemothorax are discussed above, and are rarely life-threatening. Otherwise, the most common complication is progressive tissue damage or scarring related to inflammation, and in extremely rare cases malignant transformation of the endometrial tissue.