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Inguinal Hernia

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Overview

An inguinal hernia describes the protrusion of abdominal or pelvic contents through the inguinal canal which often, but not always, exits the external inguinal ring resulting in a groin lump. Inguinal hernias are the most common type of abdominal hernia, making up 75% of cases.

Indirect vs. Direct Hernias

Clinical significance

Inguinal hernias can be described as direct or indirect, however, this distinction can only be confirmed reliably during surgery by identifying the hernia’s relations to the inferior epigastric vessels.

Trying to distinguish between two via a history and clinical examination is unreliable, and up to the point of surgery and treatment, patients are effectively managed the same, regardless of type.

Differences

For those who are interested, the anatomical differences are as follows:

  • Indirect inguinal hernias (~80%):
    • Due to protrusion through the processus vaginalis when it fails to close completely after embryonic testicular descent. The hernia can enter the scrotum and is more prone to causing scrotal pain.
    • Lateral to the inferior epigastric vessels
    • Often congenital, nearly always seen in paediatric cases, and can be seen in adults
  • Direct inguinal hernias (~20%):
    • Due to protrusion through a weak point in the posterior wall of the inguinal canal known as Hesselbach’s triangle.
    • Medial to the inferior epigastric vessels
    • Often seen in adults and more common with age as the abdominal wall weakens

Epidemiology

  • Inguinal hernias account for 75% of abdominal wall hernias
  • Men account for 90% of inguinal hernias
  • Incidence increases with age with a peak in >75 years old
  • Inguinal hernias can be present congenitally or in infants
    • Male infants are more commonly affected 

Risk Factors

  • Male sex – both in adults and infants
  • Older age (usually >75 years old)
  • Family history
  • Prematurity
  • Causes of increased intra-abdominal pressure such as:
    • Obesity
    • Pregnancy
    • Heavy lifting or straining
    • Frequent or hard coughing (e.g. secondary to COPD) and/or sneezing
    • Vomiting and/or straining during defecation
  • Connective tissue disorders: Marfan syndrome and Ehlers-Danlos syndrome

Presentation

Overview

The presentation of an inguinal hernia can be an asymptomatic groin swelling, a symptomatic groin swelling, a scrotal swelling, or in some cases, acute abdominal pain due to strangulation. Key features include:

  • A groin lump that is superior and medial to the pubic tubercle:
    • It may disappear when the patient lies down and may appear with lifting or causes of increased intra-abdominal pressure
    • They may have no pain but can cause discomfort and aches, particularly with activity
    • Indirect hernias are more likely to cause scrotal pain and a ‘dragging sensation’
  • A cough impulse may be seen:
    • Coughing increases intra-abdominal pressure, which may increase swelling and make the lump more prominent
  • The groin lump may be incarcerated:
    • The lump cannot be reduced, but there are no features of strangulation
  • In rare cases, complications may occur:
    • Strangulation may be present:
      • Features include severe abdominal pain, nausea, vomiting, and fever, the hernia may be tender, warm, and red or purple
    • Features of small bowel obstruction may be present if the hernia contains parts of the small bowel

Referral and Investigations

Referral

Arrange immediate hospital admission if a complication such as strangulation or bowel obstruction is suspected.

For all other patients where hospital admission is not needed:

  • If <18 years old – urgently refer to a paediatric surgeon to be seen within 2 weeks
  • If >18 years old – refer all patients to consider surgery:
    • If irreducible or partially reducible, make an urgent referral (seen within 2 weeks)
    • If symptomatic but reducible, routinely refer based on clinical judgement

Investigations

In secondary care, ultrasound scans may be used if there is diagnostic doubt. MRI or CT scanning may be performed.

Management

Inguinal hernias in adults

Due to the risk of complications including strangulation and bowel obstruction (even though they are rare in inguinal hernia), all patients should be offered surgery even if asymptomatic as long as they are fit to do so.

Overall, mesh repairs are associated with the lowest recurrence rates:

  • Unilateral inguinal hernias: generally repaired via an open approach
  • Bilateral/recurrent inguinal hernias: generally repaired via laparoscopy

Surgery is usually performed as a day case. For 7 days after, the patient should avoid driving and lifting. Patients can return to non-strenuous manual work after 2-3 weeks.

For people who are unfit for/refuse surgery, a hernia truss may be used, however, this is not recommended as a definitive form of treatment.

Paediatric inguinal hernia

  • If first few months of life – repair urgently due to high risk of strangulation
  • >1 year old – repair electively as the strangulation risk is lower

Complications

  • Hernia recurrence – may occur in up to 15% of cases
  • Chronic pain (>3 months) – may occur in up to 10% of cases
  • Incarceration, strangulation, and intestinal obstruction – rare, but possible

Prognosis

  • In most cases, the prognosis is excellent after surgery
  • Up to 10% of patients may have chronic groin pain after surgery. This is more common if patients had groin pain before surgery.

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