Why do indirect inguinal hernias present with protrusions lateral to the right inferior epigastric artery (IEA)?

From the Guidelines

Indirect inguinal hernias present with protrusions lateral to the right inferior epigastric artery (IEA) because they occur through a patent processus vaginalis, which is a remnant of the peritoneal lining that failed to obliterate during fetal development 1.

Key Points

• The processus vaginalis is an extension of the peritoneal lining that accompanies the testis during its descent through the inguinal canal.
• Normally, the processus vaginalis obliterates and involutes, but in some cases, it remains patent, allowing fluid or intra-abdominal structures to herniate through it.
• The relation of the processus vaginalis with testicular descent explains why more than 90% of pediatric inguinal hernias are diagnosed in boys.
• Involution of the left processus vaginalis precedes that of the right, which is consistent with the observation that 60% of indirect inguinal hernias occur on the right side 1.

Clinical Implications

The understanding of the embryological development of the processus vaginalis and its relation to indirect inguinal hernias is crucial for the diagnosis and management of these conditions.

• Clinicians should be aware of the higher incidence of indirect inguinal hernias on the right side and the association with patent processus vaginalis.
• The use of laparoscopy in the diagnosis and treatment of inguinal hernias, including indirect inguinal hernias, has been explored in various studies, with some suggesting its feasibility and safety in emergency settings 1. However, the provided evidence does not directly address the presentation of indirect inguinal hernias in relation to the inferior epigastric artery (IEA). The key takeaway remains that indirect inguinal hernias are associated with a patent processus vaginalis, which is a critical factor in their development.

From the Research

Presentation of Indirect Inguinal Hernias

Indirect inguinal hernias typically present with protrusions that are related to the position of the inferior epigastric artery (IEA). The key factor in understanding their presentation is the anatomy of the inguinal region and the path that the hernia sac takes.

Anatomical Considerations

• The deep inguinal ring, through which indirect inguinal hernias pass, is generally located lateral to the inferior epigastric vessels 2, 3.
• However, the exact position of the deep inguinal ring can vary, and it has been found to be medial or above the femoral artery in some cases 4.
• The relationship between the hernia sac and the inferior epigastric artery is crucial for distinguishing between direct and indirect inguinal hernias 3, 5.

Characteristics of Indirect Inguinal Hernias

• Indirect inguinal hernias protrude posterolateral and superior to the course of the inferior epigastric vessels 3.
• They pass through the deep inguinal ring and into the inguinal canal, beside and in contact with the spermatic cord but outside of its covering fasciae 2.
• The presence of multiple hernia sacs in the inguinal hernia, as seen in rare cases like the "Jammu, Kashmir and Ladakh Hernia", can increase the risk of recurrence if not detected and properly addressed 6.

Diagnostic Considerations

• Imaging studies, such as CT scans, can be useful in diagnosing inguinal hernias and distinguishing between direct and indirect types based on their relationship to the inferior epigastric artery 3, 5.
• 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.