The patient presents with a protrusion near the neck or between the ribs. The mass becomes prominent when the patient is straining or coughing. In asymptomatic individuals, lung hernia is incidentally detected in a chest X-ray taken for another reason. On physical examination, a prominence or mass is seen during Valsalva maneuver.

Lung hernia (Sibson hernia) is a protrusion of lung outside of thoracic wall. In 20% patients with lung hernia, the incidence is congenital. In 80% of the cases, the hernia is noted after chest trauma, thoracic surgery or certain pulmonary diseases. Congenital hernia occurs because of the weakness of the suprapleural membrane or neck muscles. In pulmonary diseases such as asthma, frequent coughing can lead to high intra thoracic pressure, causing the lung to herniate out. Lung hernia may occur near the neck (cervical), between the ribs (intercostal), near the vertebrae (paravertebral) or near the sternum (parasternal).

A scaphoid abdomen (sucked inwards) may be the presenting symptom in a newborn.

Treatment for a diaphragmatic hernia usually involves surgery, with acute injuries often repaired with monofilament permanent sutures.

The Bochdalek hernia, also known as a postero-lateral diaphragmatic hernia, is the most common manifestation of CDH, accounting for more than 95% of cases. In this instance the diaphragm abnormality is characterized by a hole in the postero-lateral corner of the diaphragm which allows passage of the abdominal viscera into the chest cavity. The majority of Bochdalek hernias (80–85%) occur on the left side of the diaphragm, a large proportion of the remaining cases occur on the right side. To date, it carries a high mortality and an active area of clinical research.

The diagnosis of congenital diaphragmatic eventration is used when there is abnormal displacement (i.e. elevation) of part or all of an otherwise intact diaphragm into the chest cavity. This rare type of CDH occurs because in the region of eventration the diaphragm is thinner, allowing the abdominal viscera to protrude upwards.

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.

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.

In normal Bochdalek hernia cases, the symptoms are often observable simultaneously with the baby's birth. A few of the symptoms of a Bochdalek Hernia include difficulty breathing, fast respiration and increased heart rate. Also, if the baby appears to have cyanosis (blue-tinted skin) this can also be a sign. Another way to differentiate a healthy baby from a baby with Bochdalek Hernia, is to look at the chest immediately after birth. If the baby has a Bochdalek Hernia it may appear that one side of the chest cavity is larger than the other and or the abdomen seems to be concave (caved in).

A Bochdalek hernia is one of two forms of a congenital diaphragmatic hernia, the other form being Morgagni hernia. A Bochdalek hernia is a congenital abnormality in which an opening exists in the infant's diaphragm, allowing normally intra-abdominal organs (particularly the stomach and intestines) to protrude into the thoracic cavity. In the majority of patients, the affected lung will be deformed, and the resulting lung compression can be life-threatening. Bochdalek hernias occur more commonly on the posterior left side (85%, versus right side 15%). This type of hernia was first studied and documented by the Czech Anatomist and Pathologist, Vincenz Alexander Bochdalek (1801–1883).

As differential diagnoses, a subphrenic abscess, bowel interposed between diaphragm and liver (Chilaiditi syndrome), and linear atelectasis at the base of the lungs can simulate free air under the diaphragm on a chest X-ray.

Hiatal hernia has often been called the "great mimic" because its symptoms can resemble many disorders. Among them, a person with a hiatal hernia can experience dull pains in the chest, shortness of breath (caused by the hernia's effect on the diaphragm), heart palpitations (due to irritation of the vagus nerve), and swallowed food "balling up" and causing discomfort in the lower esophagus until it passes on to the stomach. In addition, hiatal hernias often result in heartburn but may also cause chest pain or pain with eating.

In most cases however, a hiatal hernia does not cause any symptoms. The pain and discomfort that a patient experiences is due to the reflux of gastric acid, air, or bile. While there are several causes of acid reflux, it occurs more frequently in the presence of hiatal hernia.

In newborns, the presence of Bochdalek hernia can be recognised from symptoms such as difficulty breathing fast respiration, increased heart rate.

When present, pneumoperitoneum can often be seen on projectional radiography, but small amounts are often missed, and CT scan is nowadays regarded as a criterion standard in the assessment of a pneumoperitoneum. CT can visualize quantities as small as 5 cm³ of air or gas.

Signs that can be seen on projectional radiography are the "double wall sign" (also called "Rigler's sign") and the "football sign".

The "double wall sign" marks the presence of air on both sides of the intestine. However, a false double wall sign can result from two loops of bowel being in contact with one another. The sign is named after Leo George Rigler. It is not the same as Rigler's triad.

The "football sign" is when the abdomen appears as a large oval radiolucency reminiscent of an American football on a supine projectional radiograph. The football sign is most frequently seen in infants with spontaneous or iatrogenic gastric perforation causing pneumoperitoneum. It is also seen in bowel obstruction with secondary perforation, as in Hirschprung disease, midgut volvulus, meconium ileus and intestinal atresia. Iatrogenic causes like endoscopic perforation may also give football sign.

The syndrome has five characteristic findings:

- Omphalocele

- Anterior diaphragmatic hernia

- Sternal cleft with or without ectopia cordis

- Diaphragmatic pericardium defects (no diaphragmatic pericardium)

- Intracardiac defect: ventricular septal defect, diverticulum of the left ventricle, Tetralogy of Fallot

The following are risk factors that can result in a hiatus hernia.

- Increased pressure within the abdomen caused by:

- Heavy lifting or bending over

- Frequent or hard coughing

- Hard sneezing

- Violent vomiting

- Straining

- Stress

By far the most common hernias develop in the abdomen, when a weakness in the abdominal wall evolves into a localized hole, or "defect", through which adipose tissue, or abdominal organs covered with peritoneum, may protrude. Another common hernia involves the spinal discs and causes "sciatica". A hiatus hernia occurs when the stomach protrudes into the "mediastinum" through the esophageal opening in the diaphragm.

Hernias may or may not present with either pain at the site, a visible or palpable lump, or in some cases more vague symptoms resulting from pressure on an organ which has become "stuck" in the hernia, sometimes leading to organ dysfunction. Fatty tissue usually enters a hernia first, but it may be followed or accompanied by an organ.

Hernias are caused by a disruption or opening in the fascia, or fibrous tissue, which forms the abdominal wall. It is possible for the bulge associated with a hernia to come and go, but the defect in the tissue will persist.

Symptoms and signs vary depending on the type of hernia. Symptoms may or may not be present in some inguinal hernias. In the case of reducible hernias, a bulge in the groin or in another abdominal area can often be seen and felt. When standing, such a bulge becomes more obvious. Besides the bulge, other symptoms include pain in the groin that may also include a heavy or dragging sensation, and in men, there is sometimes pain and swelling in the scrotum around the testicular area.

Irreducible abdominal hernias or incarcerated hernias may be painful, but their most relevant symptom is that they cannot return to the abdominal cavity when pushed in. They may be chronic, although painless, and can lead to strangulation (loss of blood supply), obstruction (kinking of intestine), or both. Strangulated hernias are always painful and pain is followed by tenderness. Nausea, vomiting, or fever may occur in these cases due to bowel obstruction. Also, the hernia bulge in this case may turn red, purple or dark and pink.

In the diagnosis of abdominal hernias, imaging is the principal means of detecting internal diaphragmatic and other nonpalpable or unsuspected hernias. Multidetector CT (MDCT) can show with precision the anatomic site of the hernia sac, the contents of the sac, and any complications. MDCT also offers clear detail of the abdominal wall allowing wall hernias to be identified accurately.

An epigastric hernia is a type of hernia which may develop in the epigastrium (upper, central part of the abdomen). Epigastric hernias usually appear in adults.

Unlike the benign diastasis recti, epigastric hernia may trap fat and other tissues inside the opening of the hernia, causing pain and tissue damage.

Complications may arise post-operation, including rejection of the mesh that is used to repair the hernia. In the event of a mesh rejection, the mesh will very likely need to be removed. Mesh rejection can be detected by obvious, sometimes localized swelling and pain around the mesh area. Continuous discharge from the scar is likely for a while after the mesh has been removed.

A surgically treated hernia can lead to complications such as inguinodynia, while an untreated hernia may be complicated by:

- Inflammation

- Obstruction of any lumen, such as bowel obstruction in intestinal hernias

- Strangulation

- Hydrocele of the hernial sac

- Hemorrhage

- Autoimmune problems

- Irreducibility or Incarceration, in which it cannot be reduced, or pushed back into place, at least not without very much external effort. In intestinal hernias, this also substantially increases the risk of bowel obstruction and strangulation.

Ectopia cordis (Greek: ""away / out of place"" + Latin: ""heart"") is a congenital malformation in which the heart is abnormally located either partially or totally outside of the thorax. The ectopic heart can be found along a spectrum of anatomical locations, including the neck, chest, or abdomen. In most cases, the heart protrudes outside the chest through a split sternum.

Mendelson's syndrome is characterised by a bronchopulmonary reaction following aspiration of gastric contents during general anaesthesia due to abolition of the laryngeal reflexes. The main clinical features are signs of general hypoxia, two to five hours after anaesthesia. Such features may include cyanosis, dyspnea, fever, pulmonary wheeze, crepitant rales, rhonchi, and tachycardia with a low blood pressure. Decreased arterial oxygen tension is also likely to be evident. Pulmonary edema can cause sudden death or death may occur later from pulmonary complications.

Petit's hernia is a hernia that protrudes through the lumbar triangle. This triangle lies in the posterolateral abdominal wall and is bounded anteriorly by the free margin of external oblique muscle, posteriorly by the latissimus dorsi and inferiorly by the iliac crest. The neck (the spot where the hernia protrudes into the opening) is large, and therefore this hernia has a lower risk of strangulating than some other hernias.

Petit's hernia occurs more often in males than in females and more often on the left side than on the right.

Flat-chested kitten syndrome (FCKS), is a disorder in cats, wherein kittens develop a compression of the thorax (chest/ribcage) caused by lung collapse. This is a soft-tissue problem and is not caused by vertebral or bony malformation. However lung collapse can be a secondary symptom caused by bony deformity affecting the thorax such as pectus excavatum. In mild cases, the underside of the chest becomes flattened (hence the name of the condition); in extreme cases the entire thorax is flattened, looking as if the kitten has been stepped on. The kitten will appear to go from normal to flat in the space of about 2–3 hours, and will usually then stabilise.

FCKS is most frequently caused by collapsed lungs (and not as formerly believed, by a muscle spasm in the intercostal muscles). There are numerous causes for lung collapse, and therefore numerous causes for FCKS. One possible cause for flat chestedness that develops soon after birth is atelectasis.

Causes of atelectasis include insufficient attempts at respiration by the newborn, bronchial obstruction, or absence of surfactant (a substance secreted by alveoli that coats the lungs and prevents the surfaces from sticking together). Lack of surfactant reduces the surface area available for effective gas exchange causing lung collapse if severe. There can be many reasons for atelectasis in kittens, but probably the commonest cause is prematurity. Newborn atelectasis would not be unusual in a very large litter of kittens (such as 10), where the size of the litter may lead all the kittens to be small and mildly underdeveloped.

Unlike human babies, kittens are born very immature: blind, deaf, the intestinal tract not fully developed etc., so even slight prematurity may tip them over the edge from being viable to non viable. Many FCKS kittens may have fallen just the wrong side of this boundary in their development at the time of birth. Further, if a kitten does not scream or open its lungs well enough at birth, even if it is fully mature and has sufficient surfactant, it may end up with atelectasis. Patches of atelectasis in the lungs mean that part of a lung is not operating properly. If the kitten goes to sleep and its respiratory rate drops, the patches of atelectasis can slowly expand until large areas of the lung collapse and cannot be reinflated. Good advice to any breeder therefore would be to ensure that kittens cry loudly when they are born, to make sure that the airways are clear, but also that the lungs expand as fully as possible. (This was the reason newborn babies were always held upside down immediately after birth (so that any residual fluid drains downwards) and smacked to make them cry strongly.)

Some kittens suffer from congenital 'secondary' atelectasis, which presents shortly after birth. There have been no reports of kittens born flat (primary atelectasis). Hyaline membrane disease is a type of respiratory distress syndrome of the newborn in which there is formation of a hyaline-like membrane lining the terminal respiratory passages, and this may also be a (rarer) cause of FCKS. Pressure from outside the lung from fluid or air can cause atelectasis as well as obstruction of lung air passages by mucus resulting from various infections and lung diseases – which may explain the development of FCKS in older kittens (e.g. 10 days old) who are not strong enough to breathe through even a light mucus, or who may have inhaled milk during suckling.

Tumors and inhaled objects (possible if bedding contains loose fluff) can also cause obstruction or irritation of the airway, leading to lung collapse and secondary atelectasis. In an older cat the intercostal muscles are so well developed, and the ribs rigid enough that the ribcage will not flatten if the lung collapses: in kittens the bones are much more flexible, and the tendons and muscles more flaccid, allowing movement of the thorax into abnormal positions.

Other causes of lung collapse can include diaphragmatic hernia, or diaphragmatic spasm (breeders report the position of the gut and thorax as appearing to be like a 'stalled hiccup'). Diaphragmatic spasm is easily checked by pinching the phrenic nerve in the neck between the fingertips. Kittens with this type of FCKS will improve almost immediately, but may require repeated pinching to prevent the spasm from recurring.

Computed tomography scans of the suspected areas with intravenous contrast can assist in diagnosis.

Pentalogy of Cantrell (or thoraco-abdominal syndrome) is a rare syndrome that causes defects involving the diaphragm, abdominal wall, pericardium, heart and lower sternum.

Its prevalence is less than 1 in 1000000.

It was characterized in 1958.

A locus at Xq25-26 has been described.

A hernia is caused by the protrusion of a viscus (in the case of groin hernias, an intraabdominal organ) through a weakness in the containing wall. This weakness may be inherent, as in the case of inguinal, femoral and umbilical hernias. On the other hand, the weakness may be caused by surgical incision through the muscles of the abdominal/thoracic wall. Hernias occurring through these are called incisional hernias.

Femoral hernias occur just below the inguinal ligament, when abdominal contents pass through a naturally occurring weakness called the femoral canal. Femoral hernias are a relatively uncommon type, accounting for only 3% of all hernias. While femoral hernias can occur in both males and females, almost all of them develop in women because of the wider bone structure of the female pelvis. Femoral hernias are more common in adults than in children. Those that do occur in children are more likely to be associated with a connective tissue disorder or with conditions that increase intra-abdominal pressure. Seventy percent of pediatric cases of femoral hernias occur in infants under the age of one.

A reducible femoral hernia occurs when a femoral hernia can be pushed back into the abdomen, either spontaneously or with manipulation, but most likely, spontaneously. This is the most common type of femoral hernia and is usually painless.

An irreducible femoral hernia occurs when a femoral hernia becomes stuck in the femoral canal. This can cause pain and a feeling of illness.

An obstructed femoral hernia occurs when a part of the intestine becomes intertwined with the hernia, causing an intestinal obstruction. The obstruction may grow and the hernia can become increasingly painful. Vomiting may also result.

A strangulated femoral hernia occurs when a femoral hernia blocks blood supply to part of the bowel - the loop of bowel loses its blood supply. Strangulation can happen in all hernias, but is more common in femoral and inguinal hernias due to their narrow "necks". Nausea, vomiting, and severe abdominal pain may occur with a strangulated hernia. This is a medical emergency. A strangulated intestine can result in necrosis (tissue death) followed by gangrene (tissue decay). This is a life-threatening condition requiring immediate surgery.

A femoral hernia may be either reducible or irreducible, and each type can also present as either (or both) obstructed or strangulated.

The term incarcerated femoral hernia is sometimes used, but may have different meanings to different authors and physicians. For example: "Sometimes the hernia can get stuck in the canal and is called an irreducible or incarcerated femoral hernia." "The term 'incarcerated' is sometimes used to describe an [obstructed] hernia that is irreducible but not strangulated. Thus, an irreducible, obstructed hernia can also be called an incarcerated one." "Incarcerated hernia: a hernia that cannot be reduced. May lead to bowel obstruction but is not associated with vascular compromise."

A hernia can be described as reducible if the contents within the sac can be pushed back through the defect into the peritoneal cavity, whereas with an incarcerated hernia, the contents are stuck in the hernia sac.

However, the term "incarcerated" seems to always imply that the femoral hernia is at least irreducible.