From the Guidelines
Indirect inguinal hernias present with protrusions lateral to the inferior epigastric artery (IEA) because they occur through a patent processus vaginalis (PPV), which is a natural weakness in the abdominal wall, specifically at the internal inguinal ring, located lateral to the IEA 1.
Key Factors
- The processus vaginalis is an extension of the peritoneal lining that defines the path through which the testis descends from its retroperitoneal, intra-abdominal location through the inguinal canal 1.
- Incomplete involution of the processus vaginalis results in a PPV, allowing intra-abdominal structures such as bowel to herniate, resulting in an indirect inguinal hernia 1.
- The relation of the processus vaginalis with testicular descent is thought to explain why more than 90% of pediatric inguinal hernias are diagnosed in boys, and why 60% of indirect inguinal hernias occur on the right side 1.
Clinical Implications
- The anatomical location of the internal inguinal ring, lateral to the IEA, allows the hernia to protrude through the inguinal canal, resulting in a bulge that is typically lateral to the IEA.
- Understanding the underlying anatomy and pathophysiology of indirect inguinal hernias is crucial for accurate diagnosis and effective management, prioritizing morbidity, mortality, and quality of life as the primary outcomes.
From the Research
Presentation of Indirect Inguinal Hernias
Indirect inguinal hernias typically present with protrusions lateral to the right inferior epigastric artery (IEA) due to their anatomical characteristics.
- The hernia sac emerges through a weakness in the deep inguinal ring, lateral to the inferior epigastric vessels, and passes into the inguinal canal beside and in contact with the cord but outside of its covering fasciae 2.
- Indirect inguinal hernias protrude posterolateral and superior to the course of the inferior epigastric vessels, which distinguishes them from direct inguinal hernias that protrude anteromedial and inferior to the course of these vessels 3.
Anatomical Classification
The classification of inguinal hernias into indirect and direct types is based on their anatomical characteristics and relationship to the inferior epigastric vessels.
- Indirect inguinal hernias are usually congenital, forming a sac in the core of the spermatic cord covered by the internal spermatic, cremasteric, and external spermatic fasciae 2.
- Direct inguinal hernias are acquired, with the sac lying beside or behind the cord, and protrude anteromedial and inferior to the course of the inferior epigastric vessels 3.
Diagnostic Considerations
The diagnosis of indirect inguinal hernias can be facilitated by imaging studies, such as CT scans, which can help identify the relationship of the hernia to the inferior epigastric vessels and other anatomical landmarks.
- The lateral crescent sign, which represents lateral compression and stretching of the inguinal canal fat and contents by the hernia sac, may be useful in the diagnosis of early direct inguinal hernias 3.
- The pubic tubercle can serve as a reliable CT landmark in distinguishing between different types of groin hernias, including indirect inguinal hernias 4.