Inguinal Hernia

Aka: Inguinal Hernia, Scrotal Hernia, Indirect Inguinal Hernia, Indirect Hernia, Direct Inguinal Hernia

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II. Definitions

  1. Groin Hernia
    1. Hernias surrounding or within Hesselbach's Triangle
    2. Groin Hernias include indirect and Direct Inguinal Hernias and Femoral Hernias
  2. Indirect Inguinal Hernia
    1. Protrusion of tissue through the Internal Inguinal Ring, lateral to the inferior epigastric vessels
  3. Direct Inguinal Hernia
    1. Protrusion of tissue through the Inguinal Canal's posterior wall, medial to the inferior epigastric vessels
  4. Femoral Hernia
    1. Protrusion of tissue below the inguinal ligament and medial to the femoral artery and vein

III. Epidemiology

  1. Incidence of Groin Hernias: 1.6 Million per year in U.S.
  2. Inguinal Hernia is the most common Hernia type
    1. Inguinal Hernia accounts for 75% of all Hernias
    2. Inguinal Hernia accounts for 96% Groin Hernias (other 4% are femoral)
    3. Results in 700,000 groin Hernia Repairs annually in U.S.
  3. Inguinal Hernias are bilateral in 20% of cases
  4. Gender predisposition
    1. Inguinal Hernias: Male by 9 to 1 ratio
    2. Femoral Hernias: More common in women
  5. Peak age: 40-59 years old
  6. Lifetime
  7. Lifetime Prevalence
    1. Groin Hernia: 27% in men, 3% in women
    2. Inguinal Hernia: 10%
  8. Children account for 5% of Inguinal Hernia cases
    1. See Inguinal Hernia in Children

IV. Risk Factors

  1. Men
    1. Hiatal Hernia (2 fold increased Inguinal Hernia risk)
    2. Normal weight or low BMI (lower risk in obese men)
    3. Radical Prostatectomy history
    4. Pelvic region Radiation Therapy
    5. Systemic Connective Tissue Disease
  2. Women
    1. Tall height
    2. Chronic Cough
    3. Umbilical Hernia
    4. Older age

V. Types

  1. Background: Anatomy
    1. See Hesselbach's Triangle
    2. See Inguinal Canal
  2. Indirect Inguinal Hernia (most common in men and women)
    1. Course
      1. Hernia sac passes outside Hesselbach's Triangle (lateral to the inferior epigastric vessels)
      2. Herniates via Inguinal Canal
        1. Enters through Internal Inguinal Ring (Lateral to inferior epigastric artery)
        2. See Inguinal Canal for anatomic course
        3. Canal carries spermatic cord in men and round ligament in women
      3. May result in Scrotal Hernia in males
      4. More commonly on right in males (due to right Testicle migration lags the left in development)
    2. Pathophysiology
      1. Nonobliterated processus vaginalis (congenital)
      2. Internal abdominal ring weakened fascia
      3. Decreased muscular tone
      4. Increased abdominal pressure
  3. Direct Inguinal Hernia
    1. Hernia sac passes within Hesselbach's Triangle (medial inguinal fossa)
    2. Breaches posterior inguinal wall
    3. Hernia develops medial to inferior epigastric vessels
    4. Pathophysiology
      1. Usually occurs in males
      2. Congenital weakness of medial inguinal fossa musculature in some cases
      3. Acquired deficiency in transversus abdominis Muscle

VI. Symptoms

  1. Asymptomatic in up to one third of patients (especially in direct Hernias)
  2. Groin Pain or (dull Sensation)
    1. Intensity varies from mild to severe
    2. Burning or dull ache Sensation may be present
    3. Increased pain with valsalva (coughing, straining, lifting)
    4. Severe acute pain may suggest Incarcerated Hernia
  3. Bulging, localized fullness or heaviness in the groin
    1. Progressively larger over time
    2. Increased with upright position and valsalva, coughing or straining
    3. Decreased when supine

VII. Signs

  1. See Inguinal Canal Exam (for males)
  2. Palpable defect or swelling may be present
    1. Indirect Hernia may bulge at Internal Inguinal Ring
      1. Look for bulge site at mid-inguinal ligament
    2. Direct Hernia may bulge at External Inguinal Ring
      1. Look for bulge site at pubic tubercle
      2. Occurs just above inguinal ligament
      3. Seen medial and inferior to Indirect Hernia bulge
  3. Distinguishing indirect and direct Hernias difficult
    1. Experienced clinicians are incorrect in 30% of cases
    2. Indirect Inguinal Hernia palpation difficult in women
    3. Inguinal Hernias difficult to palpate in children

VIII. Differential Diagnosis

  1. See Groin Pain Causes
  2. See Scrotal Pain
  3. See Groin Swelling
  4. Athletic Pubalgia (Sports Hernia)
    1. Seen in high intensity athletes
    2. Hernia symptoms with no inguinal bulge on examination
    3. Pain reproduced with hip adduction against resistance
  5. Adductor Strain
  6. Osteitis Pubis
    1. Pain at Symphysis Pubis
  7. Testicular Torsion
    1. Especially in young males with unilateral Scrotal Pain

IX. Imaging

  1. Indications: Imaging is not required in most cases of Inguinal Hernia in men
    1. Distinguish from other causes of Groin Pain (e.g. Sports Hernia, Hydrocele)
    2. Groin Hernia evaluation in women
    3. Post-operative pain, recurrent Hernia or other post-operative complication
  2. Modalities
    1. Inguinal Ultrasound (excellent first-line study for diagnosis of occult Hernia)
      1. Color flow doppler differentiates Hernia from round ligament varicosities in pregnancy
      2. Test Sensitivity: 33 to 86%
      3. Test Specificity: 71 to 90%
    2. CT Pelvis
      1. Distinguishes inguinal from Femoral Hernias
      2. Test Sensitivity: 80%
      3. Test Specificity: 65%
    3. CT Pelvis with Herniography (contrast injection into Hernia sack)
      1. Test Sensitivity: 91%
      2. Test Specificity: 83%
    4. MRI Pelvis (performed with patient performing Valsalva Maneuver)
      1. Consider in Sports Hernia or occult Groin Hernia evaluation
      2. Test Sensitivity: 91%
      3. Test Specificity: 92%

X. Imaging: Inguinal Ultrasound

  1. Technique: Ultrasound in various patient positions
    1. Supine
    2. Upright
    3. Valsalva Maneuver
  2. Efficacy
    1. High Test Sensitivity: >90%
    2. High Test Specificity: 82-86%
      1. Distinguish Incarcerated Hernia from firm mass

XI. Management

  1. Small, first, incidental or minimally symptomatic Hernia
    1. Observation is reasonable if Hernia is easily reducible and function is not limited by pain
    2. Incarceration rate in 2 years is 0.3%
    3. Fitzgibbons (2006) JAMA 295(3):285-92 +PMID:16418463 [PubMed]
  2. Indications for repair without significant delay
    1. See Herniorrhaphy
    2. Non-pregnant women
      1. Higher risk for Femoral Hernias (associated with higher Strangulation risk)
    3. Large or recurrent Hernias
      1. Repair is recommended within one month of diagnosis

XII. Complications

  1. Incarcerated Hernia
    1. Painless entrapment of bowel (contrast with the pain and local inflammation of a Strangulated Hernia)
    2. Risk of Small Bowel Obstruction
    3. Reduced with patient lying supine in Trendelenburg position
      1. Examiner holds gentle pressure on the Herniated bulge for up to 15 minutes
      2. Stop and obtain immediate surgical Consultation for Strangulation if pain before or during the procedure
  2. Strangulated Hernia
    1. Surgical emergency with vascular compromise and high risk of infarcted bowel
  3. Richter Hernia
    1. Rare, but life-threatening complication of Groin Hernia in which part of intestinal wall is entrapped

XIII. References

  1. Degowin (1987) Diagnostic Examination, p. 489-96
  2. Goroll (2000) Primary Care Medicine, p. 431-4
  3. Stevens (2013) Crit Dec Emerg Med 27(9): 2
  4. Bax (2001) Am Fam Physician 59(4):143-56 [PubMed]
  5. LeBlanc (2013) Am Fam Physician 87(12): 844-8 [PubMed]
  6. Shakil (2020) Am Fam Physician 102(8): 487-92 [PubMed]

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