An inguinal hernia forms when a soft tissue, often part of the intestine, protrudes through a weak area in the lower abdominal wall, typically in the groin region. This protrusion creates a visible bulge that can cause discomfort or pain, particularly during activities like coughing or lifting. While the condition can sometimes be present from birth, it frequently develops over time due to a combination of muscle weakening and increased pressure within the abdomen.
The Anatomy of Inguinal Hernias
The inguinal region, located where the lower abdomen meets the thigh, contains a natural passageway known as the inguinal canal. This canal, present on both sides of the body, serves as a route for structures such as nerves and blood vessels to pass between the abdomen and the genital area. In males, the spermatic cord travels through this canal, while in females, it carries the round ligament of the uterus.
The abdominal wall in this area is composed of several layers, including skin, fat, and multiple muscle layers encased in fibrous tissues called fascia. A hernia develops when there is a defect or weakening in these layers, particularly in the transversalis fascia, a deep layer of the abdominal wall. The inguinal canal itself is approximately 4 to 6 centimeters long in adults.
Mesh Placement in Open Hernia Repair
Open inguinal hernia repair involves making a single incision in the groin area to directly access the hernia. Surgeons manually push the protruding tissue back into the abdominal cavity. To reinforce the abdominal wall and prevent recurrence, a synthetic mesh is then placed.
One common technique for open repair is “onlay” placement, where the mesh is positioned on the superficial side of the muscle layers, over the defect. Another approach involves placing the mesh in a “preperitoneal” position, between the muscle layers and the peritoneum, the inner lining of the abdominal cavity. The mesh is secured with sutures to cover the weakened area, creating a strong, tension-free repair.
Mesh Placement in Laparoscopic Hernia Repair
Laparoscopic hernia repair, a minimally invasive approach, utilizes several small incisions and a camera to guide the surgeon. This method allows for mesh placement from within the abdominal wall, reinforcing the area. The primary goal is to position the mesh in the preperitoneal space, an area in front of the peritoneum but behind the muscle layers.
Two main laparoscopic techniques achieve this preperitoneal placement. The Transabdominal Preperitoneal (TAPP) approach involves entering the abdominal cavity, incising the peritoneum over the hernia, and then placing the mesh in the preperitoneal space. The peritoneum is then closed over the mesh. In contrast, the Totally Extraperitoneal (TEP) approach avoids entering the abdominal cavity entirely, with the surgeon creating and working within the preperitoneal space to place the mesh without disturbing the peritoneum.
How Mesh Placement Influences Outcomes
The specific anatomical plane where surgical mesh is placed influences the outcome of an inguinal hernia repair. Placing the mesh in the preperitoneal space, as is common in laparoscopic techniques, results in a more stable repair because intra-abdominal pressure helps to hold the mesh against the weakened area. This “physiologic” mesh location places the mesh away from sensitive groin nerves.
Conversely, mesh placement directly in contact with nerves, particularly in more superficial planes, can increase the risk of chronic groin pain due to nerve irritation or entrapment. Surgeons consider nerve anatomy during placement, often avoiding fixation in areas known as the “triangle of pain” to minimize this complication. While mesh generally reduces hernia recurrence rates, the chosen placement strategy is important for both the long-term integrity of the repair and the patient’s comfort and recovery experience.