David M. Krpata and Michael J. Rosen

Introduction

Approximately 75% of hernias occur in the groin, which makes inguinal hernia repair one of the most common procedures performed by the general surgeon. The anatomy can be difficult to grasp, however, and before performing inguinal herniorrhaphy, the surgeon must understand inguinal anatomy to avoid complications such as chronic pain and recurrence.

Terminology

In referring to inguinal hernias, a major defining point is location of the defect—direct versus indirect. This distinction is strictly anatomic because the operative repair is the same for both types. Approximately two thirds of inguinal hernias are indirect. Men are 25 times more likely to have an inguinal hernia than women, and indirect hernias are more common regardless of gender. A direct inguinal hernia is defined as a weakness in the transversalis fascia within the area bordered by the inguinal ligament inferiorly, the lateral border of the rectus sheath medially, and the epigastric vessels laterally (Fig. 28-1). This area is referred to as Hesselbach’s triangle.

Located lateral to the inferior epigastric vessels, an indirect inguinal hernia is characterized by the protrusion of the hernia sac through the internal inguinal ring toward the external inguinal ring and, at times, into the scrotum. Indirect inguinal hernias result from a failure of the processus vaginalis to close completely (Fig. 28-2). An inguinal hernia that has direct and indirect components is referred to as a pantaloon hernia.

A hernia is defined as reducible if its contents can be placed back into the peritoneal cavity, alleviating their displacement through the musculature. In contrast, a hernia with contents that cannot be reduced is termed incarcerated (Fig. 28-3). If the blood supply to the contents of the hernia is compromised, the hernia is defined as strangulated. Strangulation is a potentially fatal complication of a hernia and should always be considered a surgical emergency. Less common inguinal hernias include Amyand’s hernia, with the appendix (normal or acutely inflamed) contained in the hernia sac, and Littre’s hernia, which contains a Meckel’s diverticulum.

Surgical Approach

Open inguinal hernia repair has evolved from primary tissue repairs (tension repairs) to tension-free repair with mesh placement. However, an understanding of tissue-based repairs remains important, particularly for surgeons repairing inguinal hernias in the setting of contamination. Tension-free repair with mesh can be performed with many different techniques. Several unique mesh modifications enable the surgeon to patch the defect through an anterior approach (Lichtenstein), use a prosthetic plug (plug and patch), or place a bilayered mesh for anterior and posterior repair. Each of these approaches has unique advantages and disadvantages. This chapter focuses on the Lichtenstein repair, which remains one of the most common open inguinal hernia repairs.

To understand the anterior approach, the surgeon must appreciate the layers of the abdominal wall and their relation to the inguinal canal. The layers and the location of their neurovascular structures include skin, subcutaneous fat (e.g., Camper’s and Scarpa’s fasciae), muscles (external and internal oblique, transversus abdominis), transversalis fascia, preperitoneal fat, and peritoneum (Fig. 28-4, A).