Inguinal and Femoral Hernia: Anatomy, Examination and Repair

A hernia is the protrusion of an organ or tissue through a weakness in the wall of the cavity that normally contains it. Groin hernias are the most common type. Most are inguinal, but femoral hernias are especially important because they are more likely to strangulate.

Anatomy made simple

The inguinal canal runs from the deep (internal) ring, just above the midpoint of the inguinal ligament, to the superficial (external) ring, above and medial to the pubic tubercle. It carries the spermatic cord in men and the round ligament in women.

Types of groin hernia

• Indirect inguinal hernia
  • the most common type at all ages
  • passes through the deep ring, lateral to the inferior epigastric vessels, along the canal
  • may reach the scrotum
  • caused by a patent processus vaginalis; common in children, especially preterm babies
• Direct inguinal hernia
  • pushes directly through the posterior wall of the canal, medial to the inferior epigastric vessels, in Hesselbach's triangle
  • seen in older men
  • caused by weakness of the abdominal wall
• Femoral hernia
  • passes through the femoral canal
  • the neck lies below and lateral to the pubic tubercle
  • more common in women, but inguinal hernias are still more common in women overall
  • its narrow neck gives a high risk of strangulation

Risk factors

• Male sex.
• Increasing age.
• Prematurity (in infants).
• Chronic cough, constipation and straining (for example with prostate enlargement).
• Heavy lifting.
• Obesity.
• Previous surgery.
• Family history.

Clinical features

• A groin lump that may come and go, often more obvious on standing or coughing.
• A dragging discomfort.
• Cough impulse on examination.
• Reducible: the lump goes back with gentle pressure or lying down.
• Irreducible (incarcerated): cannot be pushed back.
• Obstructed: irreducible with bowel obstruction (colicky pain, vomiting, distension, no flatus).
• Strangulated: the blood supply is cut off. The lump is tense, tender, red and painful, and the patient may be systemically unwell. This is a surgical emergency.

Examination tips

• Examine the patient standing and lying.
• Check the other side.
• Decide whether you can "get above" a scrotal swelling. If you cannot, it is a hernia.
• Assess reducibility.
• Deep ring occlusion test: controlling the hernia by pressing over the deep ring suggests an indirect hernia, but clinical tests are not very reliable for telling indirect from direct.
• Differential diagnosis of a groin lump:
  • lymph nodes
  • saphena varix
  • femoral aneurysm
  • hydrocele
  • undescended testis
  • lipoma
  • psoas abscess

Investigations

The diagnosis is usually clinical. Ultrasound helps in uncertain cases; CT is used in complex or obese patients, or when obstruction is suspected.

Management

• Symptomatic inguinal hernias: surgical repair is usually advised. Open Lichtenstein tension-free mesh repair, or laparoscopic repair (TEP or TAPP), especially for bilateral or recurrent hernias.
• Minimally symptomatic inguinal hernias in men: "watchful waiting" is an option in selected patients.
• Femoral hernias: repair promptly, because of the strangulation risk.
• Infants: repair inguinal hernias early (herniotomy).
• Strangulated or obstructed hernias: resuscitate, then emergency surgery, with bowel resection if it is not viable.

Exam pearls

• Indirect hernias lie lateral, and direct hernias medial, to the inferior epigastric vessels.
• Femoral hernias lie below and lateral to the pubic tubercle; inguinal hernias lie above and medial.
• Always examine the hernial orifices in a patient with bowel obstruction.

For more, see our Surgery Companion (abdominal wall chapter) and Exam Night Notes 1.0: Gastro Surgery.

Test yourself

5 exam-style single-best-answer questions. Choose your answer, then tap “Show answer”.

1. An indirect inguinal hernia passes:

   1. Lateral to the inferior epigastric vessels through the deep ring
   2. Through the femoral canal
   3. Through the umbilicus
   4. Through the obturator foramen
   5. Medial to the inferior epigastric vessels
   Show answer

   Answer: A. Lateral to the inferior epigastric vessels through the deep ring
   Indirect hernias enter the deep ring lateral to the inferior epigastric vessels.

2. A groin hernia lying below and lateral to the pubic tubercle is:

   1. Femoral
   2. Indirect inguinal
   3. Direct inguinal
   4. Umbilical
   5. Spigelian
   Show answer

   Answer: A. Femoral
   Femoral hernias lie below and lateral; inguinal above and medial to the pubic tubercle.

3. Why should femoral hernias be repaired promptly?

   1. High risk of strangulation due to a narrow neck
   2. They become malignant
   3. They are cosmetic
   4. They always resolve
   5. They cause infertility
   Show answer

   Answer: A. High risk of strangulation due to a narrow neck
   The narrow femoral canal makes strangulation more likely.

4. A tense, tender, red irreducible hernia in an unwell patient. Management?

   1. Reassure
   2. Antibiotics only
   3. Elective repair in 6 weeks
   4. Truss
   5. Resuscitate and emergency surgery
   Show answer

   Answer: E. Resuscitate and emergency surgery
   Strangulation is a surgical emergency; non-viable bowel may need resection.

5. Hesselbach's triangle is the site of which hernia?

   1. Indirect inguinal
   2. Incisional
   3. Obturator
   4. Direct inguinal
   5. Femoral
   Show answer

   Answer: D. Direct inguinal
   Direct hernias push through the weak posterior wall in Hesselbach's triangle.

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Disclaimer

For education and exam preparation only. This is not medical advice and must not be used to diagnose or treat patients. Always follow current clinical guidelines and the advice of qualified senior colleagues.