An external hernia is an abnormal protrusion of intra-abdominal tissue through a fascial defect in the abdominal wall.* Although most hernias (75%) occur in the groin, incisional hernias represent an increasing proportion (15%-20%), with umbilical and other ventral hernias comprising the remainder. Generally, a hernial mass is composed of covering tissues (skin, subcutaneous tissues, etc), a peritoneal sac, and any contained viscera. Particularly if the neck of the sac is narrow where it emerges from the abdomen, bowel protruding into the hernia may become obstructed or strangulated. If the hernia is not repaired early, the defect may enlarge and operative repair may become more complicated. The definitive treatment of hernia 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 irreducible (incarcerated) 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, though incarceration is necessary for obstruction or strangulation to occur.
Though the lumen of a segment of bowel within the hernia sac may become obstructed, there may initially be no interference with blood supply. Compromise to the blood supply of the contents of the sac (eg, omentum or intestine) results in a strangulated hernia, in which gangrene of the contents of the sac 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. A strangulated Richter hernia may spontaneously reduce and the gangrenous piece of intestine be overlooked at operation. The bowel may subsequently perforate, with 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 are fleshy laterally and aponeurotic medially. Their aponeuroses form investing layers of the strong rectus abdominis muscles above the semilunar line. Below this line, the aponeurosis lies entirely in front of the muscle. Between the two vertical rectus muscles, the aponeuroses meet again to form the linea alba, which is well defined only above the umbilicus. The subcutaneous fat contains the Scarpa fascia—a misnomer, since it is only a condensation of connective tissue with no substantial strength.
In the groin, an indirect inguinal hernia results when obliteration of the processus vaginalis, the peritoneal extension accompanying the testis in its descent ...