Should I order an ultrasound of the scrotum or inguinal canal to assess for inguinal hernia?

Ultrasound for Inguinal Hernia Assessment

Ultrasound of the scrotum and inguinal region is the recommended first-line imaging modality for assessing suspected inguinal hernias, offering high sensitivity without radiation exposure. 1, 2

Diagnostic Approach for Inguinal Hernias

Initial Assessment

• Physical examination is usually sufficient to diagnose inguinal hernias in most cases, especially in men, by feeling for a bulge or impulse while the patient coughs or strains 1, 3
• Ultrasound is indicated when:
  • Physical findings are inconclusive 3, 4
  • The patient is female (hernias are more difficult to diagnose on physical exam) 1
  • There is suspicion of a recurrent hernia 2, 3
  • Complications are suspected (strangulation, incarceration) 4
  • An acute scrotum is present 4

Benefits of Ultrasound Evaluation

• Provides both anatomical detail and assessment of blood flow through Duplex Doppler imaging 2
• Can identify the contents of the hernia sac (bowel, omentum, reproductive organs) 4, 5
• Helps evaluate for potential vascular complications and perfusion status 2, 4
• Can detect inflammatory changes in surrounding structures 2
• Particularly valuable in pediatric patients due to non-invasive nature and absence of radiation 4, 5

Ultrasound Technique

• Grayscale ultrasound identifies structural abnormalities and hernia contents 2
• Color Doppler assessment evaluates:
  • Testicular perfusion in males 2, 4
  • Intestinal perfusion if bowel is present in the hernia 4, 5
  • Hyperemia suggesting inflammatory processes 2

When to Consider Advanced Imaging

• MRI has higher sensitivity (94.5%) and specificity (96.3%) than ultrasound (92.7% and 81.5% respectively) for diagnosing inguinal hernias 6
• Consider MRI when:
  • Ultrasound findings are equivocal or nondiagnostic 2, 6
  • Clinical suspicion remains high despite negative ultrasound 1, 6
  • There is concern for occult hernias 1
• CT abdomen and pelvis should be considered as a second-line imaging modality when there is suspicion of a more extensive process extending into the abdomen or pelvis 2

Special Considerations

• In pediatric patients, inguinal hernias are more common in males (>90%) than females due to embryological differences in development 7, 8
• Ultrasound is particularly valuable in pediatric patients with suspected inguinal hernia to evaluate for:
  • Intestinal obstruction 5
  • Strangulation (indicated by akinetic dilated bowel loop) 4
  • Impaired testicular/ovarian perfusion 4
• Contralateral involvement should be assessed with ultrasound in pediatric patients with unilateral hernias, as bilateral hernias are common 4

Common Pitfalls

• Failing to use Doppler assessment, which is crucial for evaluating vascular complications 2, 4
• Not examining the patient in both supine and standing positions, as some hernias may reduce when supine 3
• Missing small hernias that may only be visible during Valsalva maneuver 1, 6
• Overlooking female inguinal hernias, which are less common but still clinically significant 8, 1