Differential Diagnosis of Inguinal Hernias
The key conditions that mimic inguinal hernias include femoral hernias, hydroceles, lymphadenopathy, lipomas, undescended testes (in males), and in athletes, sportsman's hernia (athletic pubalgia). 1, 2
Primary Differential Considerations
Femoral Hernias
- Femoral hernias are the most critical differential diagnosis because they have a higher risk of strangulation and require urgent surgical intervention 1
- These hernias pass posterior to the inguinal ligament, while inguinal hernias pass anterior to it 3, 4
- On CT imaging, femoral hernias characteristically show a localized sac lateral to the pubic tubercle with compression of the femoral vein (100% sensitivity in one study) 4
- Femoral hernias are more common in women and present lower in the groin, below the inguinal ligament 5
Hydroceles
- Present as scrotal swelling that transilluminates with light, unlike hernias 2
- Ultrasonography is particularly useful to differentiate hydroceles from inguinal hernias when the diagnosis is uncertain 1, 2
- In infants, congenital hydroceles result from patent processus vaginalis and usually resolve spontaneously within 18-24 months 6
Lymphadenopathy
- Inguinal lymph nodes can enlarge due to infection, malignancy, or inflammatory conditions 2
- Unlike hernias, lymph nodes are firm, non-reducible, and do not change with coughing or straining 2
- Multiple nodes may be palpable rather than a single bulge 2
Lipomas of the Cord
- Present as soft, non-reducible masses in the inguinal region 5
- Do not demonstrate an impulse with coughing or Valsalva maneuver 2
Specialized Differential Diagnoses
Sportsman's Hernia (Athletic Pubalgia)
- Occurs in athletes without a palpable bulge or impulse on physical examination 1, 5
- Presents with chronic groin pain exacerbated by activity 5
- MRI has higher sensitivity and specificity than ultrasonography for diagnosing occult hernias when clinical suspicion is high despite negative ultrasound findings 7
Undescended or Ectopic Testis (in Males)
- In male infants, palpating the testis to ensure it is present in the scrotum and not involved in the hernia is crucial 1
- An undescended testis may be mistaken for an inguinal hernia 6
Other Rare Groin Hernias
- Obturator hernias and Spiegelian hernias are rare but should be considered in atypical presentations 5
Key Diagnostic Pitfalls to Avoid
- Failing to examine both sides for hernias - contralateral patent processus vaginalis occurs in 64% of infants younger than 2 months 1
- Missing femoral hernias by not examining below the inguinal ligament 1
- Not assessing for complications such as incarceration or strangulation (irreducibility, tenderness, erythema, systemic symptoms) 1
- In women, ultrasonography is often needed as groin hernias are more difficult to diagnose on physical examination alone 7
Imaging Considerations
- Ultrasonography is the first-line imaging modality when diagnosis is uncertain, for recurrent hernias, suspected hydroceles, or surgical complications 1, 2, 7
- MRI should be used for occult hernias in athletes when ultrasonography is negative but clinical suspicion remains high 7
- CT scanning is useful in emergency settings to assess for complications like bowel obstruction or strangulation, and can differentiate femoral from inguinal hernias based on anatomical relationships 1, 3, 4