INTRODUCTION AND DEFINITIONS
Abdominal wall integrity relies on organized anatomic layering of muscle and fascia to contain the intra-abdominal contents. A defect in one or more layers of fasciae can result in a hernia, which represents an abnormal protrusion of intra-abdominal contents through the fascial defect. Groin hernias represent the most common type of abdominal wall hernias (∼75%), whereas ventral, umbilical, and other types of hernias compose the rest. Of the various types of ventral hernias, incisional hernias represent the majority of these, stemming from a failure of appropriate healing following a surgical incision. In general, a hernia is composed of covering tissues (eg, skin, subcutaneous tissues), a peritoneal sac (hernia sac), and various contents including preperitoneal fat, omental fat, and/or any visceral organs. In particular, if the neck of the hernia defect is narrow where it emerges from the abdomen, bowel protruding into the hernia may become compromised (obstruction or strangulation). If the hernia is not repaired early, the defect may enlarge, and operative repair may become more complicated. Although some hernias can be observed over time, the definitive treatment of hernias is operative repair.
A reducible hernia is one in which the contents of the sac return to the abdomen spontaneously or with manual pressure when the patient is recumbent. An incarcerated (irreducible) hernia is one whose contents cannot be returned to the abdomen, usually because they are trapped by a narrow neck. The term incarceration does not imply obstruction, inflammation, or ischemia of the herniated organs, although incarceration is typically a requisite for obstruction or strangulation to occur.
Compromise of bowel or other viscera can occur with incarcerated hernias. Bowel obstruction results from kinking or twisting of bowel within the hernia, which in turn leads to dilation of the proximal bowel due to blockage of the bowel lumen. However, obstruction does not imply any compromise to the blood supply. Compromise to the blood supply of the hernia contents (eg, omentum or intestine) results in a strangulated hernia, in which gangrene of the viscera has occurred. The incidence of strangulation is higher in femoral than in inguinal hernias, but strangulation may occur in any hernia.
An uncommon and dangerous type of hernia, a Richter hernia, occurs when only part of the circumference of the bowel becomes incarcerated or strangulated in the fascial defect. Because the bowel is not obstructed, and because only a portion of the bowel wall becomes strangulated, a Richter hernia commonly presents late in the clinical course after focal perforation and resultant peritonitis.
All groin hernias protrude through the myopectineal orifice of Fruchaud, a weakness or defect in the transversalis fascia, an aponeurosis located just outside the peritoneum. External to the transversalis fascia are found the transversus abdominis, internal oblique, and external oblique muscles, which ...