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).

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.

It involves three major defects:

- A failure of the diaphragm to completely close during development

- Herniation of the abdominal contents into the chest

- Pulmonary hypoplasia

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.

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).

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.

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.

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

Hernias present as bulges in the groin area that can become more prominent when coughing, straining, or standing up. They are rarely painful, and the bulge commonly disappears on lying down. Mild discomfort can develop over time. The inability to "reduce", or place the bulge back into the abdomen usually means the hernia is 'incarcerated' which requires emergency surgery.

Significant pain is suggestive of strangulated bowel (an incarcerated indirect inguinal hernia).

As the hernia progresses, contents of the abdominal cavity, such as the intestines, liver, can descend into the hernia and run the risk of being pinched within the hernia, causing an intestinal obstruction. If the blood supply of the portion of the intestine caught in the hernia is compromised, the hernia is deemed "strangulated" and gut ischemia and gangrene can result, with potentially fatal consequences. The timing of complications is not predictable.

The causes of umbilical hernia are congenital and acquired malformation, but an apparent third cause is really a cause of a different type, a paraumbilical hernia.

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.

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

They typically present when standing erect as a groin lump or bulge, which may differ in size during the day, based on internal pressure variations of the intestine. The bulge or lump typically is smaller or may not be visible in a prone position.

They may or may not be associated with pain. Often, they present with a varying degree of complication ranging from irreducibility through intestinal obstruction to frank gangrene of contained bowel. The incidence of strangulation in femoral hernias is high. A femoral hernia has often been found to be the cause of unexplained small bowel obstruction.

The obvious finding may be a lump in the groin. Cough impulse is often absent and should not be relied on solely when making a diagnosis of femoral hernia. The lump is more globular than the pear shaped lump of the inguinal hernia. The bulk of a femoral hernia lies below an imaginary line drawn between the anterior superior iliac spine and the pubic tubercle (which essentially represents the inguinal ligament) whereas an inguinal hernia starts above this line. Nonetheless, it is often impossible to distinguish the two preoperatively.

Importantly, an umbilical hernia must be distinguished from a paraumbilical hernia, which occurs in adults and involves a defect in the midline near to the umbilicus, and from omphalocele.

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

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

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.

The direct inguinal hernia enters through a weak point in the fascia of the abdominal wall, and its sac is noted to be medial to the inferior epigastric vessels. Direct inguinal hernias may occur in males or females, but males are ten times more likely to get a direct inguinal hernia.

A direct inguinal hernia protrudes through a weakened area in the transversalis fascia near the medial inguinal fossa within an anatomic region known as the inguinal or Hesselbach's triangle, an area defined by the edge of the rectus abdominis muscle, the inguinal ligament and the inferior epigastric artery. These hernias are capable of exiting via the superficial inguinal ring and are unable to extend into the scrotum.

When a patient suffers a simultaneous direct and indirect hernia on the same side, the result is called a "pantaloon" hernia (because it looks like a pair of pants, with the epigastric vessels in the crotch), and the defects can be repaired separately or together.

Since the abdominal walls weaken with age, direct hernias tend to occur in the middle-aged and elderly. This is in contrast to indirect hernias which can occur at any age including the young, since their etiology includes a congenital component where the inguinal canal is left more patent (compared to individuals less susceptible to indirect hernias). Additional risk factors include chronic constipation, overweight/obesity, chronic cough, family history and prior episodes of direct inguinal hernias.

Clinically, incisional hernias present as a bulge or protrusion at or near the area of a surgical incision. Virtually any prior abdominal operation can develop an incisional hernia at the scar area (provided adequate healing does not occur due to infection), including large abdominal procedures such as intestinal or vascular surgery, and small incisions, such as (appendix removal or abdominal exploratory surgery). While incisional hernias can occur at any incision, they tend to occur more commonly along a straight line from the xiphoid process of the sternum straight down to the pubis, and are more complex in these regions. Hernias in these areas have a high rate of recurrence if repaired via a simple suture technique under tension. For this reason, it is especially advised that these be repaired via a tension free repair method using a synthetic mesh.

Incisional hernias are usually caused by a weakness of the surgical wounds, which may be caused by hematoma, seroma, or infection, all of which result in decreased wound healing. They may also be caused by increased intra-abdominal pressure due to a chronic cough (as in COPD), constipation, urinary obstruction (as in BPH), pregnancy, or ascites. They can also result from poor surgical technique.

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.

Perineal hernia is a hernia involving the perineum (pelvic floor). The hernia may contain fluid, fat, any part of the intestine, the rectum, or the bladder. It is known to occur in humans, dogs, and other mammals, and often appears as a sudden swelling to one side (sometimes both sides) of the anus.

A common cause of perineal hernia is surgery involving the perineum. Perineal hernia can be caused also by excessive straining to defecate (tenesmus). Other causes include prostate or urinary disease, constipation, anal sac disease (in dogs), and diarrhea. Atrophy of the levator ani muscle and disease of the pudendal nerve may also contribute to a perineal hernia.

In humans, a major cause of perineal hernia is perineal surgery without adequate reconstruction. In some cases, particularly surgeries to remove the coccyx and distal sacrum, adequate reconstruction is very difficult to achieve. The posterior perineum is a preferred point of access for surgery in the pelvic cavity, particularly in the presacral space. Surgeries here include repair of rectal prolapse and anterior meningocele, radical perineal prostatectomy, removal of tumors including sacrococcygeal teratoma, and coccygectomy. Perineal hernia is a common complication of coccygectomy in adults, but not in infants and children (see coccygectomy).

The standard surgical technique for repair of perineal hernia uses a prosthetic mesh, but this technique has a high rate of failure due to insufficient anchoring. Promising new techniques to reduce the rate of failure include an orthopedic anchoring system, a gluteus maximus muscle flap, an acellular human dermis graft, and an acellular pig collagen graft.

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 Spigelian hernia (or lateral ventral hernia) is a hernia through the Spigelian fascia, which is the aponeurotic layer between the rectus abdominis muscle medially, and the semilunar line laterally. These are generally interparietal hernias, meaning that they do not lie below the subcutaneous fat but penetrate between the muscles of the abdominal wall; therefore, there is often no notable swelling.

Spigelian hernias are usually small and therefore risk of strangulation is high. Most occur on the right side. (4th–7th decade of life.) Compared to other types of hernias they are rare.