A chylothorax (or chyle leak) is a type of pleural effusion. It results from lymph formed in the digestive system called chyle accumulating in the pleural cavity due to either disruption or obstruction of the thoracic duct.

In people on a normal diet, this effusion can be identified by its turbid, milky white appearance, since chyle contains high levels of triglycerides. It is important to distinguish chylothorax from pseudochylothorax (pleural effusions high in cholesterol), which has a similar appearance, but is caused by more chronic inflammatory processes, and has a different treatment.

The condition is rare but serious, and appears in all mammals. It results from leakage of lymph fluid from the thoracic duct (or one of its tributaries). This can result from direct laceration (e.g., from surgery) or from nontraumatic causes. The most common nontraumatic cause is malignancy, especially lymphoma. Less common is left-heart failure, infections, and developmental abnormalities such as Down syndrome and Noonan syndrome.

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).

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.

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.

Signs and symptoms of spontaneous subcutaneous emphysema vary based on the cause, but it is often associated with swelling of the neck and chest pain, and may also involve sore throat, neck pain, difficulty swallowing, wheezing and difficulty breathing. Chest X-rays may show air in the mediastinum, the middle of the chest cavity. A significant case of subcutaneous emphysema is easy to detect by touching the overlying skin; it feels like tissue paper or Rice Krispies. Touching the bubbles causes them to move and sometimes make a crackling noise. The air bubbles, which are painless and feel like small nodules to the touch, may burst when the skin above them is palpated. The tissues surrounding SCE are usually swollen. When large amounts of air leak into the tissues, the face can swell considerably. In cases of subcutaneous emphysema around the neck, there may be a feeling of fullness in the neck, and the sound of the voice may change. If SCE is particularly extreme around the neck and chest, the swelling can interfere with breathing. The air can travel to many parts of the body, including the abdomen and limbs, because there are no separations in the fatty tissue in the skin to prevent the air from moving.

The average age of onset is the early to mid 30s. Exertional dyspnea and spontaneous pneumothorax have been reported as the initial presentation of the disease in 49% and 46% of patients, respectively.

Diagnosis is typically delayed 5 to 6 years. The condition is often misdiagnosed as asthma or chronic obstructive pulmonary disease. The first pneumothorax precedes the diagnosis of LAM in 82% of patients. The consensus clinical definition of LAM includes multiple symptoms:

- Fatigue

- Cough

- Hemoptysis (rarely massive)

- Chest pain

- Chylous complications arising from lymphatic obstruction, including

- Chylothorax

- Chylous ascites

- Chylopericaridium

- Chyloptysis

- Chyluria

- Chyle in vaginal discharge

- Chyle in stool.

- Angiomyolipomas (fatty kidney tumors) are present in about 30% of patients with sporadic LAM and up to 90% of patients with TSC-LAM. Angiomyolipomas can sometimes spontaneously bleed, causing pain or hypotension.

- Cystic lymphangiomas or lymph nodes with hypodense centers, which mimic necrotizing lymphomas, ovarian or renal cancers, or other malignancies can occur in the retroperitoneum, pelvis or mediastinum.

Lung destruction in LAM is a consequence of diffuse infiltration by neoplastic smooth muscle-like cells that invade all lung structures including the lymphatics, airway walls, blood vessels and interstitial spaces. The consequences of vessel and airway obstruction include chylous fluid accumulations, hemoptysis, airflow obstruction and pneumothorax. The typical disease course displays progressive dyspnea on exertion, spaced by recurrent pneumothoraces and in some patients, chylous pleural effusions or ascites.

Most people have dyspnea on exertion with daily activities by 10 years after symptom onset. Many patients require supplemental oxygen over that interval.

Symptoms that arise from disease of the cardiothoracic region include a chronic cough, wheezing, dyspnea (shortness of breath)—especially serious when occurring at rest or when lying down—fever, chest pain, rapid heartbeat, dizziness, anxiety, and coughing up blood or chyle. As the deranged lymphatic vessels invade the organs and tissues in the chest they put stress on the heart and lungs, interfering with their ability to function normally. Additionally, these lymphatic vessels may leak, allowing fluid to accumulate in the chest, which puts further pressure on the vital organs, thus increasing their inability to function properly. Accumulations of fluid and chyle are named based on their contents and location: pulmonary edema (the presence of fluid and/or chyle in the lung), pleural effusions (fluid in the lung lining), pericardial effusions (fluid in the heart sack), chylothorax (chyle in the pleural cavity); and chylopericardium (chyle in the heart sack).

Subcutaneous emphysema is a common result of certain types of surgery; for example it is not unusual in chest surgery. It may also occur from surgery around the esophagus, and is particularly likely in prolonged surgery. Other potential causes are positive pressure ventilation for any reason and by any technique, in which its occurrence is frequently unexpected. It may also occur as a result of oral surgery, laparoscopy, and cricothyrotomy. In a pneumonectomy, in which an entire lung is removed, the remaining bronchial stump may leak air, a rare but very serious condition that leads to progressive subcutaneous emphysema. Air can leak out of the pleural space through an incision made for a thoracotomy to cause subcutaneous emphysema. On infrequent occasions, the condition can result from dental surgery, usually due to use of high-speed tools that are air driven. These cases result in usually painless swelling of the face and neck, with an immediate onset, the crepitus (crunching sound) typical of subcutaneous emphysema, and often with subcutaneous air visible on X-ray.

One of the main causes of subcutaneous emphysema, along with pneumothorax, is an improperly functioning chest tube. Thus subcutaneous emphysema is often a sign that something is wrong with a chest tube; it may be clogged, clamped, or out of place. The tube may need to be replaced, or, when large amounts of air are leaking, a new tube may be added.

Since mechanical ventilation can worsen a pneumothorax, it can force air into the tissues; when subcutaneous emphysema occurs in a ventilated patient, it is an indication that the ventilation may have caused a pneumothorax. It is not unusual for subcutaneous emphysema to result from positive pressure ventilation. Another possible cause is a ruptured trachea. The trachea may be injured by tracheostomy or tracheal intubation; in cases of tracheal injury, large amounts of air can enter the subcutaneous space. An endotracheal tube can puncture the trachea or bronchi and cause subcutaneous emphysema.

Lymphangiomatosis is a multi-system disorder. Symptoms depend on the organ system involved and, to varying degrees, the extent of the disease. Early in the course of the disease patients are usually asymptomatic, but over time the abnormally proliferating lymphatic channels that constitute lymphangiomatosis are capable of massive expansion and infiltration into surrounding tissues, bone, and organs. Because of its slow course and often vague symptoms, the condition is frequently under-recognized or misdiagnosed.

Early signs of disease in the chest include wheezing, cough, and feeling short of breath, which is often misdiagnosed as asthma. The pain that accompanies bone involvement may be attributed to "growing pains" in younger children. With bone involvement the first indication for disease may be a pathological fracture. Symptoms may not raise concern, or even be noted, until the disease process has advanced to a point where it causes restrictive compression of vital structures. Further, the occurrence of chylous effusions seems to be unrelated to the pathologic "burden" of the disease, the extent of involvement in any particular tissue or organ, or the age of the patient. This offers one explanation as to why, unfortunately, the appearance of chylous effusions in the chest or abdomen may be the first evidence of the disease.

Following are some of the commonly reported symptoms of lymphangiomatosis, divided into the regions/systems in which the disease occurs:

As with other forms of pulmonary edema, the hallmark of SIPE is a cough which may lead to frothy or blood-tinged sputum. Symptoms include:

- Shortness of breath out of proportion to effort being expended.

- Crackles, rattling or ‘junky’ feelings deep in the chest associated with breathing effort – usually progressively worsening with increasing shortness of breath and may be cause for a panic attack

- Cough, usually distressing and productive or not of a little pink, frothy or blood-tinged sputum (hemoptysis)

The wetsuit may feel as though it is hindering breathing ability.

In minor injuries with little bleeding, there may be abdominal pain, tenderness in the epigastrium and pain in the left flank. Often there is a sharp pain in the left shoulder, known as Kehr's sign. In larger injuries with more extensive bleeding, signs of hypovolemic shock are most prominent. This might include a rapid pulse, low blood pressure, rapid breathing, paleness, and anxiety.

Lymphangioleiomyomatosis (LAM) is a rare, progressive and systemic disease that typically results in cystic lung destruction. It predominantly affects women, especially during childbearing years.

Swimming induced pulmonary edema (SIPE), also known as immersion pulmonary edema, occurs when fluids from the blood leak abnormally from the small vessels of the lung (pulmonary capillaries) into the airspaces (alveoli).

SIPE usually occurs during exertion in conditions of water immersion, such as swimming and diving. With the recent surge in popularity of triathlons and swimming in open water events there has been an increasing incidence of SIPE. It has been reported in scuba divers, apnea (breath hold) free-diving competitors combat swimmers, and triathletes. The causes are incompletely understood at the present time.

A splenic injury, which includes a ruptured spleen, is any injury to the spleen. The rupture of a normal spleen can be caused by trauma, such as a traffic collision.

Most people who develop SCSFLS feel the sudden onset of a severe and acute headache. It is a headache usually made worse by standing, typically becoming prominent throughout the day, with the pain becoming less severe when lying down. Orthostatic headaches can become chronic and disabling to the point of incapacitation. Some patients with SCSFLS will develop headaches that begin in the afternoon. This is known as "second-half-of-the-day headache". This may be an initial presentation of a spontaneous CSF leak or appear after treatment such as an epidural patch, and likely indicates a slow CSF leak.

Apart from headache, about 50% of patients experience neck pain or stiffness, nausea, and vomiting. Other symptoms include dizziness and vertigo, facial numbness or weakness, unusually blurry or double vision, neuralgia, fatigue, or a metallic taste in the mouth. Leaking CSF can sometimes be felt or observed as a discharge from the nose or ear.

Lack of CSF pressure and volume can allow the brain to sag and descend through the foramen magnum (large opening) of the occipital bone, at the base of the skull. The lower portion of the brain is believed to stretch or impact one or more cranial nerve complexes, thereby causing a variety of sensory symptoms. Nerves that can be affected and their related symptoms are detailed in the table at right.

SCSFLS is classified into two main types, cranial leaks and spinal leaks. The vast majority of leaks are spinal. Cranial leaks occur in the head. In some of these cases, CSF can be seen dripping out of the nose, or ear. Spinal leaks occur when one or more holes form in the dura along the spinal cord. Both cranial and spinal spontaneous CSF leaks cause neurological symptoms as well as spontaneous intracranial hypotension, diminished volume and pressure of the cranium. While referred to as "intracranial hypotension", the intracranial pressure may be normal, with the underlying issue instead being low-volume CSF. For this reason SCSFLS is referred to as "CSF hypovolemia" as opposed to "CSF hypotension".

Traumatic pneumorrhachis is a medical condition in which air has entered the spinal canal.

Traumatic pneumorrhachis is very rare phenomenon. Only eight cases with pneumorrhachis extending to more than one spinal region had been reported in the literature. Gordon had initially described the phenomenon of intraspinal air. The term "pneumorrhachis" was used for the first time by Newbold et al. The two subtypes of pneumorrhachis, which includes epidural or subarachnoid, are difficult to distinguish even with CT scanning. However, the presence of pneumocephalus goes more in favor of subarachnoid subtype. Goh and Yeo in their study have reported that the epidural pneumorrhachis is self-limited, whereas the more common subarachnoid pneumorrhachis type may be complicated by tension pneumocephalus and meningitis. Traumatic subarachnoid pneumorrhachis is almost always secondary to major trauma and is a marker of a severe injury. The pathophysiology described for it states that the penetrated air, which had led to the formation of pneumocephalus might have been forced caudally due to the raised intracranial pressure as a consequence of severe brain injury and patient's horizontal position allowing the entrapped air to pass through the foramen magnum into the spinal canal. Due to its rareness, asymptomatic presentation and myriad etiologies, no guidelines for its treatment or care has been described. Pneumorrhachis typically resolves spontaneously but occasionally it can have serious complications. Patient with subarachnoid pneumorrhachis should be treated meticulously and a temporary lumbar drainage may be required if they have concomitant cerebro-spinal fluid leak.

A pancreatic fistula is an abnormal communication between the pancreas and other organs due to leakage of pancreatic secretions from damaged pancreatic ducts. An "external" pancreatic fistula is one that communicates with the skin, and is also known as a pancreaticocutaneous fistula, whereas an internal pancreatic fistula communicates with other internal organs or spaces. Pancreatic fistulas can be caused by pancreatic disease, trauma, or surgery.

Anasarca, edema, is a medical condition characterized by widespread swelling of the skin due to effusion of fluid into the extracellular space.

It is usually caused by liver failure (cirrhosis of the liver), renal failure/disease, right-sided heart failure, as well as severe malnutrition/protein deficiency. The increase in salt and water retention caused by low cardiac output can also result in anasarca as a long term maladaptive response.

It can also be created from the administration of exogenous intravenous fluid. Certain plant-derived anticancer chemotherapeutic agents, such as docetaxel, cause anasarca through a poorly understood capillary leak syndrome.

In Hb Barts, the high oxygen affinity results in poor oxygen delivery to peripheral tissues, resulting in anasarca.

A cerebrospinal fluid leak (CSFL) is a medical condition where the cerebrospinal fluid(CSF) in the brain leaks out of the dura mater. This can be due to a spontaneous cerebrospinal fluid leak or result from different causes such as a lumbar puncture or physical trauma. While high CSF pressure can make lying down unbearable, low CSF pressure due to a leak can be relieved by lying flat on the back.

The most common symptoms of a CSFL is extremely high pressure in the head when sitting, standing, or bending down which can be lessened by laying down flat.

A myelogram can be used to help identify a CSFL by injecting a dye to further enhance the imaging allowing the location of the leak to be found. If it is a slow leak it may not appear on a single myelogram so more than one may be needed. Due to the ease of the procedure no anesthesia is used however a local anesthetic is given.

An epidural blood patch is the normal treatment for a CSFL, the patient's blood is drawn and it is then injected into the lumbar spine. Patients are told to lie flat without moving from 2 to 24 hours after the blood patch is done. A blood patch can be used to patch a CSFL in the cervical neck although it is rare for it to be done in that location, though it may take more than one blood patch to fully close the leak. Anesthesia is also uncommon for blood patch procedures. If you have a low pain tolerance it would be a good idea to have anesthesia for all of the procedures.

If the leak is strong or fast, the loss of CSF fluid can cause the brain to drop inside the skull due to the body's inability to replenish the CSF fluid at a quick enough pace, which would show up on a MRI of the brain. This is called a Chiari malformation where the brain is lower in the skull almost in the spinal canal.

An external pancreatic fistula is an abnormal communication between the pancreas (actually pancreatic duct) and the exterior of the body via the abdominal wall.

Loss of bicarbonate-rich pancreatic fluid via a pancreatic fistula can result in a hyperchloraemic or normal anion gap metabolic acidosis. Loss of a small volume of fluid will not cause a problem but an acidosis is common if the volume of pancreatic fluid lost from the body is large.

Penile Artery Shunt Syndrome (PASS) is an iatrogenic clinical phenomenon first described by Tariq Hakky, Christopher Yang, Jonathan Pavlinec, Kamal Massis, and Rafael Carrion within the Sexual Medicine Program in the Department of Urology, at the University of South Florida, and Ricardo Munarriz, of Boston University School of Medicine Department of Urology in 2013. It may be a cause of refractory Erectile Dysfunction in patients who have undergone Penile Revascularization Surgery.

Another cause of severe water retention is kidney failure, where the kidneys are no longer able to filter fluid out of the blood and turn it into urine. Kidney disease often starts with inflammation, for instance in the case of diseases such as nephrotic syndrome or lupus. Once again, this type of water retention is usually visible in the form of swollen legs and ankles.