Hernia

A hernia is defined as the abnormal protrusion of an organ or tissue through a defect in the wall of the cavity in which it normally resides. The term originates from Latin meaning ‘rupture’. While most commonly referring to pathological protrusions in the abdominal region, the term is also used in embryology to describe the normal temporary projection of the midgut into the extraembryonic coelom around the seventh week of gestation. Hernias vary widely in type, presentation and risk, but they share the fundamental feature of a weakness or opening in a supporting structure that allows internal tissues to protrude.
Hernias occur most frequently in the abdomen and particularly in the groin. Groin hernias include inguinal and femoral types, with inguinal hernias being the most common. Other important forms include hiatal, incisional and umbilical hernias. The condition is common globally, and prevalence rises with age. A bulge at the hernia site and pain or discomfort, especially during physical activity or straining, are typical features. Severe complications such as strangulation of the bowel can occur, requiring urgent surgical intervention.

Types of Hernias

Hernias manifest in several anatomical regions and present with distinctive characteristics.

• Inguinal hernia: The most common type, arising when abdominal contents protrude through a weak point in the inguinal canal. They occur more often on the right side and are particularly common in men.
• Femoral hernia: A less common groin hernia seen more frequently in women, with a higher likelihood of complications.
• Hiatal hernia: Occurs when part of the stomach herniates into the mediastinum via the oesophageal hiatus, often causing reflux symptoms.
• Umbilical hernia: Involves protrusion near the umbilicus and is more common in infants and individuals with increased intra-abdominal pressure.
• Incisional hernia: Appears at the site of a previous surgical incision due to weakened tissue.
• Other varieties: Include rarer forms such as diaphragmatic or internal hernias, which may be more challenging to detect clinically.

Signs and Symptoms

Hernia symptoms depend on type and severity. Groin hernias commonly present with a noticeable bulge that becomes more apparent when standing, straining or coughing. Typical symptoms include:

• pain or discomfort in the groin or abdomen,
• a dragging or heavy sensation,
• swelling in the scrotum in males,
• a bulge that may be reducible on manipulation.

Incarcerated hernias are not reducible and risk progressing to strangulation, where the blood supply to the protruding tissue—usually bowel—is compromised. Strangulated hernias are painful and may produce nausea, vomiting, fever and changes in the colour of the hernia bulge. Hiatal hernias may cause heartburn, chest pain or discomfort when eating, due to displacement of gastric contents toward the oesophagus.
Imaging such as CT scanning provides detailed visualisation of the hernia sac, its contents and complications, particularly for deep or non-palpable hernias.

Pathogenesis

Herniation arises when the structural elements of the abdominal wall—muscles, fascia and tendons—are weakened or damaged. These structures act collectively as a supportive container for abdominal organs. When intra-abdominal pressure rises, they normally counteract the force to prevent protrusion. Weakness in the wall, whether due to inherited collagen defects, surgical incisions or acquired degeneration, allows tissues to push through under pressure. Once formed, hernias tend to enlarge over time because tension increases at the defect, exacerbating the problem.
Hiatal hernias involve a similar process but originate from weakening of the diaphragmatic hiatus, allowing upward displacement of the stomach.

Causes and Risk Factors

Hernias develop from a combination of mechanical stress and underlying tissue vulnerability. Contributing factors include:

• tobacco smoking,
• chronic obstructive pulmonary disease,
• obesity,
• pregnancy,
• peritoneal dialysis,
• collagen vascular diseases,
• previous abdominal surgery such as open appendectomy,
• genetic predisposition, including heritable connective tissue weakness.

Increased intra-abdominal pressure from straining during bowel movement or urination, constipation, chronic cough, or lifting heavy weights may contribute, although evidence linking heavy lifting to groin hernias is inconclusive. Poor nutrition, muscle overexertion and ascites also increase susceptibility.

Diagnosis

Diagnosis is generally clinical, relying on the presence of a bulge, reproducible symptoms and examination findings. Imaging is used when hernias are not palpable or when the diagnosis is uncertain. For hiatal hernias, endoscopy is commonly employed to visualise the oesophagogastric junction. CT imaging provides excellent anatomical detail for abdominal hernias.

Complications

Untreated hernias may lead to significant complications:

• Bowel obstruction: particularly in intestinal hernias when loops of bowel become trapped.
• Incarceration: inability to manually reduce the hernia into the abdominal cavity.
• Strangulation: impaired blood supply leading to tissue necrosis, a surgical emergency.
• Inflammation and obstruction: of organs entrapped within the hernia sac.
• Compromised organ function: due to increased pressure on incarcerated tissues.

Additionally, hiatal hernias may predispose to gastro-oesophageal reflux, oesophagitis and, in some cases, obstruction.

Management

Management varies by hernia type, patient factors and symptom severity. In asymptomatic males with groin hernias, watchful waiting is an accepted approach, although most eventually require surgery due to pain development. In women, surgical repair is generally recommended due to the higher likelihood of femoral hernias.
Surgical options include:

• Open hernia repair: which may be performed under local anaesthesia and allows direct reinforcement of the defect.
• Laparoscopic repair: associated with reduced postoperative pain and quicker recovery.

For hiatal hernias, conservative management includes lifestyle measures such as weight loss, elevating the head of the bed and dietary adjustments. Pharmacological treatment with H₂ blockers or proton pump inhibitors may reduce reflux symptoms. Refractory cases may require laparoscopic Nissen fundoplication.

Epidemiology

Hernias represent a significant global health burden. In 2019, over three billion individuals were estimated to have inguinal, femoral or abdominal hernias, with more than one billion new cases that year. Groin hernias affect around 27 per cent of males and 3 per cent of females during their lifetime. Mortality from inguinal, femoral and abdominal hernias accounted for approximately 59,800 deaths in 2015. Hiatal hernia prevalence varies widely, with North American estimates ranging from 10 to 80 per cent.
Hernias occur most frequently in early childhood and after the age of 50. Healthcare expenditure on abdominal wall hernias is considerable, reflecting the frequency of surgical repair and postoperative care.