The diagnosis of a hiatus hernia is typically made through an upper GI series, endoscopy or high resolution manometry.

Incidence of hiatal hernias increases with age; approximately 60% of individuals aged 50 or older have a hiatal hernia. Of these, 9% are symptomatic, depending on the competence of the lower esophageal sphincter (LES). 95% of these are "sliding" hiatus hernias, in which the LES protrudes above the diaphragm along with the stomach, and only 5% are the "rolling" type (paraesophageal), in which the LES remains stationary, but the stomach protrudes above the diaphragm.

Hiatus hernia are most common in North America and Western Europe and rare in rural African communities. Some have proposed that insufficient dietary fiber and the use of a high sitting position for defecation may increase the risk.

One way to determine if a baby does in fact have a Bochdalek hernia, would be to have a pediatrician perform a physical on the infant. A chest x-ray can also be done to examine the abnormalities of not only the lungs but also the diaphragm and the intestine. In addition to these, a doctor can also take a blood test, drawing arterial blood to check and determine how well the baby is breathing and his or her ability to breathe. A chromosomal test (done by testing the blood) can also be performed to determine whether or not the problem was genetic. The doctors can also take an ultrasound of the heart (echocardiogram) to evaluate the health of the heart.

The diagnosis is largely a clinical one, generally done by physical examination of the groin. However, in obese patients, imaging in the form of ultrasonography, CT or MRI may aid in the diagnosis. An abdominal x-ray showing small bowel obstruction in a female patient with a painful groin lump needs no further investigation.

Several other conditions have a similar presentation and must be considered when forming the diagnosis: inguinal hernia, an enlarged inguinal lymph node, aneurysm of the femoral artery, saphena varix, and an abscess of the psoas.

Before birth, openings in the abdomen can usually be detected by a detailed ultrasound or AFP screening. In addition to the ultrasound or AFP scanning, it is also necessary for children with this defect to be checked for other birth defects because genetic disorders are usually associated with some of the abdominal wall defects. In looking for other genetic disorders that may be associated, Genetic counseling and further genetic testing, such as amniocentesis, are offered.

Congenital diaphragmatic hernia has a mortality rate of 40–62%, with outcomes being more favorable in the absence of other congenital abnormalities. Individual rates vary greatly dependent upon multiple factors: size of hernia, organs involved, additional birth defects, and/or genetic problems, amount of lung growth, age and size at birth, type of treatments, timing of treatments, complications (such as infections) and lack of lung function.

Bochdalek hernia can be a life-threatening condition. Approximately 85.3% of newborns born with a Bochdalek hernia are immediately high risk. Infants born with a Bochdalek hernia have a "high mortality rate due to respiratory insufficiency". Between 25–60% of infants with a Bochdalek hernia die. The lungs, diaphragm, and digestive system are all forming at the same time, so when a Bochdalek hernia permits the abdominal organs to invade the chest cavity rather than remain under the diaphragm in the correct position, it puts the infant in critical condition. These "foreign bodies" in the chest cavity compress the lungs, impairing their proper development and causing pulmonary hypoplasia. Since the lungs of infants suffering from a Bochdalek hernia have fewer alveoli than normal lungs, Bochdalek hernias are life-threatening conditions due to respiratory distress. Also, if the invasion of the intestine or stomach punctures the lung, then the lungs cannot fill completely with air. The baby will not be healthy or stable with this condition because he or she cannot take in enough air and oxygen to keep the body operating properly. Like the lungs, the intestines may also have trouble developing correctly. If the intestines are trapped within the lungs, then the lungs and intestines may not be receiving the amount of blood they need to stay healthy and function properly.

The benefits of the use of an external device to maintain reduction of the hernia without repairing the underlying defect (such as hernia trusses, trunks, belts, etc.) are unclear.

On chest radiography, a retrocardiac, gas-filled viscus may be seen in cases of intrathoracic stomach, which confirms the diagnosis. Plain abdominal radiography reveals a massively distended viscus in the upper abdomen. In organoaxial volvulus, plain films may show a horizontally oriented stomach with a single air-fluid level and a paucity of distal gas. In mesenteroaxial volvulus, plain abdominal radiographic findings include a spherical stomach on supine images and 2 air-fluid levels on erect images, with the antrum positioned superior to the fundus.

- Upper GI contrast studies:

The diagnosis of gastric volvulus is usually based on barium studies; however, some authors recommend computed tomography (CT) scanning as the imaging modality of choice.

Upper gastrointestinal (GI) contrast radiographic studies (using barium or Gastrografin) are sensitive and specific if performed with the stomach in the "twisted" state and may show an upside-down stomach. Contrast studies have been reported to have a diagnostic yield in 81–84% of patients.

Often performed for an evaluation of acute abdominal pain, a computed tomography (CT) scan can offer immediate diagnosis by showing two bubbles with a transition line. Proponents of CT scanning in the diagnosis of gastric volvulus report several benefits, including:

1. the ability to rapidly diagnose the condition based on a few coronal reconstructed images,

2. the ability to detect the presence or absence of gastric pneumatosis and free air,

3. the detection of predisposing factors (i.e., diaphragmatic or hiatal hernias), and

4. the exclusion of other abdominal pathology.

- Endoscopy:

Upper gastrointestinal (GI) endoscopy may be helpful in the diagnosis of gastric volvulus. When this procedure reveals distortion of the gastric anatomy with difficulty intubating the stomach or pylorus, it can be highly suggestive of gastric volvulus. In the late stage of gastric volvulus, strangulation of the blood supply can result in progressive ischemic ulceration or mucosal fissuring.

The nonoperative mortality rate for gastric volvulus is reportedly as high as 80%. Historically, mortality rates of 30–50% have been reported for acute gastric volvulus, with the major cause of death being strangulation, which can lead to necrosis and perforation. With advances in diagnosis and management, the mortality rate from acute gastric volvulus is 15–20% and that for chronic gastric volvulus is 0–13%.

This condition can often be diagnosed before birth and fetal intervention can sometimes help, depending on the severity of the condition.

Infants born with diaphragmatic hernia experience respiratory failure due to both pulmonary hypertension and pulmonary hypoplasia. The first condition is a restriction of blood flow through the lungs thought to be caused by defects in the lung. Pulmonary hypoplasia or decreased lung volume is directly related to the abdominal organs presence in the chest cavity which causes the lungs to be severely undersized, especially on the side of the hernia.

Survival rates for infants with this condition vary, but have generally been increasing through advances in neonatal medicine. Work has been done to correlate survival rates to ultrasound measurements of the lung volume as compared to the baby's head circumference. This figure known as the lung to head ratio (LHR). Still, LHR remains an inconsistent measure of survival. Outcomes of CDH are largely dependent on the severity of the defect and the appropriate timing of treatment.

A small percentage of cases go unrecognized into adulthood.

Many people are managed through day surgery centers, and are able to return to work within a week or two, while intense activities are prohibited for a longer period. People who have their hernias repaired with mesh often recover within a month, though pain can last longer. Surgical complications include pain that lasts more than three months, surgical site infections, nerve and blood vessel injuries, injury to nearby organs, and hernia recurrence. Pain that lasts more than three months occurs in about 10% of people following hernia repair.

Because of its sensitivity, manometry (esophageal motility study) is considered the key test for establishing the diagnosis. A catheter (thin tube) is inserted through the nose, and the patient is instructed to swallow several times. The probe measures muscle contractions in different parts of the esophagus during the act of swallowing. Manometry reveals failure of the LES to relax with swallowing and lack of functional peristalsis in the smooth muscle esophagus.

Characteristic manometric findings are:

- Lower esophageal sphincter (LES) fails to relax upon wet swallow (<75% relaxation)

- Pressure of LES 100 is considered achalasia, > 200 is nutcracker achalasia.

- Aperistalsis in esophageal body

- Relative increase in intra-esophageal pressure as compared with intra-gastric pressure

Biopsy, the removal of a tissue sample during endoscopy, is not typically necessary in achalasia but if performed shows hypertrophied musculature and absence of certain nerve cells of the myenteric plexus, a network of nerve fibers that controls esophageal peristalsis.

Abdominal wall defects can be treated surgically if there is no accompanying anomalies. The surgical procedure also called omphalocele repair/closure or gastroschisis repair/closure is not overcomplicated. The organs are normal but are misplaced.

However, if the abdominal cavity is too small or when the organs are too large or swollen to close the skin, it may be difficult to fit all the viscera into the small abdominal cavity. In such cases, the surgeon will place a covering pouch generally made of silastic, commonly called a "silo" (because it's shaped like an agricultural silo), over the abdominal organs on the outside of the infant. The silo serves to conserve heat and prevent infection. The silo is spring-loaded so that the device can be attached to the inside of the abdominal wall without sutures. The top of the silo is secured in a way that causes it to stand upright, so that the bowels are gradually coaxed into the abdominal cavity by gravity. This process can take up to a week, and final closure may be performed a few weeks later. More surgery may be required to repair the abdominal muscles at a later time.

The differential diagnosis of gastric outlet obstruction may include: early gastric carcinoma hiatal hernia, gastroesophageal reflux, adrenal insufficiency, and inborn errors of metabolism.

Symptomatic epigastric hernias are repaired with surgery. Even if they are asymptomatic, they can be surgically corrected for cosmetic reasons. In general, cosmetic surgery on infants is delayed until the infant is older and better able to tolerate anaesthesia.

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

The most confirmatory investigation is endoscopy of upper gastrointestinal tract.

Laboratory

- Individuals with gastric outlet obstruction are often hypochloremic, hypokalemic, and alkalotic due to loss of hydrogen chloride and potassium. High urea and creatinine levels may also be observed if the patient is dehydrated.

Abdominal X-ray

- A gastric fluid level may be seen which would support the diagnosis.

Barium meal and follow through

- May show an enlarged stomach and pyloroduodenal stenosis.

Gastroscopy

- May help with cause and can be used therapeutically.

Femoral hernias, like most other hernias, usually need operative intervention. This should ideally be done as an elective (non-emergency) procedure. However, because of the high incidence of complications, femoral hernias often need emergency surgery.

There is currently no medical recommendation about how to manage an inguinal hernia condition in adults, due to the fact that, until recently, elective surgery used to be recommended. The hernia truss is intended to contain a reducible inguinal hernia within the abdomen. It is not considered to provide a cure, and if the pads are hard and intrude into the hernia aperture they may cause scarring and enlargement of the aperture. In addition, most trusses with older designs are not able effectively to contain the hernia at all times, because their pads do not remain permanently in contact with the hernia. The more modern variety of truss is made with non-intrusive flat pads and comes with a guarantee to hold the hernia securely during all activities. Although there is as yet no proof that such devices can prevent an inguinal hernia from progressing, they have been described by users as providing greater confidence and comfort when carrying out physically demanding tasks. A truss also increases the probability of complications, which include strangulation of the hernia, atrophy of the spermatic cord, and atrophy of the fascial margins. This allows the defect to enlarge and makes subsequent repair more difficult. Their popularity is likely to increase, as many individuals with small, painless hernias are now delaying hernia surgery due to the risk of post-herniorrhaphy pain syndrome. The elasticised pants used by athletes also provide useful support for the smaller hernia.

Traditional "open" repair of incisional hernias can be quite difficult and complicated. The weakened tissue of the abdominal wall is re-incised and a repair is reinforced using a prosthetic mesh. Complications, particularly infection of the incision, frequently occur because of the large size of the incision required to perform this surgery. A mesh infection after this type of hernia repair most frequently requires a complete removal of the mesh and ultimately results in surgical failure. In addition, large incisions required for open repair are commonly associated with significant postoperative pain. Reported recurrence rates after open repair are up to 20% and influenced by mesh size and fixation type.

Laparoscopic incisional hernia repair is a new method of surgery for this condition. The operation is performed using surgical microscopes and specialized instruments. The surgical mesh is placed into the abdomen underneath the abdominal muscles through small incisions to the side of the hernia. In this manner, the weakened tissue of the original hernia is never re-incised to perform the repair, and one can minimize the potential for wound complications such as infections. In addition, performance of the operation through smaller incisions can make the operation less painful and speed recovery. Laparoscopic repair has been demonstrated to be safe and a more resilient repair than open incisional hernia repair.

In some communities mothers routinely push the small bulge back in and tape a coin over the palpable hernia hole until closure occurs. This practice is not medically recommended as there is a small risk of trapping a loop of bowel under part of the coin resulting in a small area of ischemic bowel. This "fix" does not help and germs may accumulate under the tape, causing infection. The use of bandages or other articles to continuously reduce the hernia is not evidence-based.

An umbilical hernia can be fixed in two different ways. The surgeon can opt to stitch the walls of the abdominal or he/she can place mesh over the opening and stitch it to the abdominal walls. The latter is of a stronger hold and is commonly used for larger defects in the abdominal wall. Most surgeons will not repair the hernia until 5–6 years after the baby is born. Most umbilical hernias in infants and children close spontaneously and rarely have complications of gastrointestinal-content incarcerations.

How far the projection of the swelling extends from the surface of the abdomen (the belly) varies from child to child. In some, it may be just a small protrusion; in others it may be a large rounded swelling that bulges out when the baby cries. It may hardly be visible when the child is quiet and or sleeping.

Normally, the abdominal muscles converge and fuse at the umbilicus during the formation stage, however, in some cases, there remains a gap where the muscles do not close and through this gap the inner intestines come up and bulge under the skin, giving rise to an umbilical hernia. The bulge and its contents can easily be pushed back and reduced into the abdominal cavity.

In contrast to an inguinal hernia, the complication incidence is very low, and in addition, the gap in the muscles usually closes with time and the hernia disappears on its own. The treatment of this condition is essentially conservative: observation allowing the child to grow up and see if it disappears. Operation and closure of the defect is required only if the hernia persists after the age of 3 years or if the child has an episode of complication during the period of observation like irreducibility, intestinal obstruction, abdominal distension with vomiting, or red shiny painful skin over the swelling. Surgery is always done under anesthesia. The defect in the muscles is defined and the edges of the muscles are brought together with sutures to close the defect. In general, the child needs to stay in the hospital for 2 days and the healing is complete within 8 days.

At times, there may be a fleshy red swelling seen in the hollow of the umbilicus that persists after the cord has fallen off. It may bleed on touch, or may stain the clothes that come in contact with it. This needs to be shown to a pediatric surgeon. This is most likely to be an umbilical polyp and the therapy is to tie it at the base with a stitch so that it falls off and there is no bleeding. Alternatively, it may be an umbilical granuloma that responds well to local application of dry salt or silver nitrate but may take a few weeks to heal and dry.

In dogs, perineal hernia usually is found on the right side. Most cases are in older intact (not neutered) male dogs (93 percent in one study). Breeds that may be at risk include Welsh Corgis, Boxers, Australian Kelpies, Boston Terriers, Collies, Dachshunds, Old English Sheepdogs, and Pekingese. Perineal hernias are rare in female dogs and uncommon in cats.

Dogs with benign prostatic hyperplasia have been found to have increased relaxin levels and suspected subsequent weakening of the pelvic diaphragm. In cats, perineal hernias are seen most commonly following perineal urethrostomy surgery or secondary to megacolon. Medical treatment consists of treatment of the underlying disease, enemas, and stool softeners. Because only about 20 percent of cases treated medically are free of symptoms, surgery is often necessary. Recurrence is common with or without surgery.

Several surgeries have been described for perineal hernias in dogs. The current standard involves transposition of the internal obturator muscle. This technique has a lower recurrence and complication rate than traditional hernia repair. A new technique uses porcine small intestinal submucosa as a biomaterial to help repair the defect. This is can also be done in combination with internal obturator muscle transposition, especially when that muscle is weak.

Surgical correction of inguinal hernias is called a hernia repair. It is not recommended in minimally symptomatic hernias, for which watchful waiting is advised, due to the risk of post herniorraphy pain syndrome. Surgery is commonly performed as outpatient surgery. There are various surgical strategies which may be considered in the planning of inguinal hernia repair. These include the consideration of mesh use (e.g. synthetic or biologic), open repair, use of laparoscopy, type of anesthesia (general or local), appropriateness of bilateral repair, etc. Laparoscopy is most commonly used for non-emergency cases, however, a minimally invasive open repair may have a lower incidence of post-operative nausea and mesh associated pain. During surgery conducted under local anaesthesia, the patient will be asked to cough and strain during the procedure to help in demonstrating that the repair is without tension and sound.

Constipation after hernia repair results in strain to evacuate the bowel causing pain, and fear that the sutures may rupture. Opioid analgesia makes constipation worse. Promoting an easy bowel motion is important post-operatively.

Surgical correction is always recommended for inguinal hernias in child.

Emergency surgery for incarceration and strangulation carry much higher risk than planned, "elective" procedures. However, the risk of incarceration is low, evaluated at 0.2% per year. On the other hand, surgery has a risk of inguinodynia (10-12%), and this is why males with minimal symptoms are advised to watchful waiting. However, if they experience discomfort while doing physical activities or they routinely avoid them by the fear of pain, they should seek surgical evaluation. For female patients, surgery is recommended even for asymptomatic patients.

Navels with the umbilical tip protruding past the umbilical skin ("outies") are often mistaken for umbilical hernias, which are a completely different shape. Treatment for cosmetic purposes is not necessary, unless there are Incarceration refers to the inability to reduce the hernia back into the abdominal cavity. Prolonged incarceration can lead to tissue ischemia (strangulation) and shock when untreated.

Umbilical hernias are rare. With a study involving Africans, 92% of children had protrusions, 49% of adults, and 90% of pregnant women. However, a much smaller amount actually suffered from hernias: only 23% of children, 8% of adults, and 15% of pregnant women.

When the orifice is small (< 1 or 2 cm), 90% close within 3 years (some sources state 85% of all umbilical hernias, regardless of size), and if these hernias are asymptomatic, reducible, and don't enlarge, no surgery is needed (and in other cases it must be considered).