Epidemiology

Herniorrhaphy (also known as hernioplasty, or surgical repair of a hernia) is a common procedure in the United States. Approximately 800,000 inguinal hernia repairs were performed in the United States in 2003; mesh was used in 90% of the cases.¹

Of groin hernias, inguinal hernias (96%) are much more common than femoral hernias (4%). The male-to-female ratio for inguinal hernias is 9 : 1, and that for femoral hernias is 1 : 4. In elderly women, femoral hernias are as common as inguinal hernias. The incidence of strangulation increases with advancing age.

Operative mortality for a strangulated hernia is 5% to 10% in patients older than 80 years, as compared with 3% for elective repair in that age group. Mortality increases to 19% when bowel necrosis is present.

The incidence of postoperative intraabdominal hernias is increasing because of the higher number of Roux-en-Y gastric bypass procedures performed each year; postoperative hernias are observed in 2.5% to 4.5% of patients undergoing bariatric surgery.

Incisional hernias of the abdominal wall occur in up to 11% of all other postoperative patients and in as many as 23% of patients with postoperative wound infections. Trocar site hernias after laparoscopic surgery are reported in up to 6% of patients. Parastomal hernia formation occurs in 28% of ileostomies and 48% of colostomies. Morbidity depends on the location and contents of the hernia, as well as the development of incarceration or strangulation.

Pathophysiology

Hernias are congenital or acquired defects in the abdominal wall that allow protrusion of intraabdominal contents through the pathologic opening. The characteristic finding consists of pain and swelling at the hernia site. Intraabdominal hernias, which can occur spontaneously or after surgery or trauma, are caused by defects in the diaphragm, mesentery, or ligamentous structures.

Incarcerated hernias are those in which abdominal contents have become trapped in the opening (i.e., nonreducible). Bowel incarceration can be manifested as pain, vomiting, or frank obstruction.

Strangulated hernias involve a compromise of the blood supply to the hernia contents. Strangulation can be manifested as fever, ischemia, or necrosis of the hernia contents and, occasionally, erythema or necrosis of the skin overlying the hernia. Smaller defects in the abdominal wall are more likely to be manifested as incarceration or strangulation.

Reduction—replacement of the hernia contents back into the abdominal cavity—is the immediate treatment of a hernia. Reduction of a hernia is accomplished by gentle pressure over the area of herniation. Reduction is assisted by use of the supine or Trendelenburg position, application of ice, analgesia, and procedural sedation to relax the musculature of the abdominal wall. Reduction should not be attempted if necrosis of the hernia contents is suspected. Definitive hernia treatment is surgical repair.

Nomenclature

Table 38.1 and Box 38.1 summarize the nomenclature of hernias, and Figures 38.1 to 38.13 illustrate some of the hernia types.

Table 38.1 Nomenclature of Hernias

Groin Hernias
Inguinal hernia (Fig. 38.1)	Physical examination cannot accurately distinguish between indirect and direct inguinal hernias
Indirect	Occurs through the inguinal canal
	Inguinal canal contents include the ilioinguinal nerve, genital branch of the genitofemoral nerve, spermatic cord in men (vas deferens, testicular artery, and vein), and round ligament in women
Direct	65% of inguinal hernias are indirect
	Weakness of the aponeurosis of the transversus abdominis and transversalis fascia in the Hesselbach triangle (the medial border of which is the lateral aspect of the rectus abdominis, the superior border is the epigastric artery, and the inferior border is the inguinal ligament)
Femoral hernia	Occurs through the femoral canal, inferior to the inguinal ligament, medial to the femoral vein
	More common in elderly, parous women
Sportsman’s hernia	Syndrome of persistent groin pain in athletes; probably caused by recurrent or persistent groin strain, osteitis pubis, or a nonpalpable hernia
	More common in kicking sports
Abdominal Wall Hernias
Anterior (Fig. 38.2)
Epigastric hernia	Occurs through the linea alba, the midline between the xiphoid line and umbilicus
Umbilical hernia	Caused by an abnormally large or weak umbilical ring
	Umbilical hernia usually closes spontaneously in infancy but does not heal in adulthood
	Rarely incarcerates in children
	Worsened by pregnancy, obesity, or cirrhosis with ascites
Spigelian hernia (Figs. 38.3 and 38.4)	Lateral ventral hernia through the spigelian zone: transversalis fascia between the lateral margin of the rectus abdominis muscle, medial margins of the external and internal obliques, and the transversus abdominis muscles
	Accounts for 1-2% of all hernias
Ventral or incisional hernia (Fig. 38.5)	Trocar sites: Difficult to recognize on physical examination Dangerous cause of early postoperative small bowel obstruction Can be the Richter type (incarceration of one intestinal wall) Iliac crest bone graft sites Parastomal hernias

 Traumatic Caused by blunt or penetrating trauma “Handlebar” hernia:

 Congenital abdominal wall defects Surgical emergencies in neonates:

Types:

Posterior (lumbar) hernias (Fig. 38.6) Bounded superiorly by the 12th rib, inferiorly by the iliac crest, posteriorly by the erector spinae muscles, and anteriorly by the posterior border of the external oblique muscle Types:

Diaphragmatic Hernias Congenital hernia (Fig. 38.7) Eventration: thin diaphragm with normal but widely spaced muscle fibers Posterolateral: through the foramen of Bochdalek Anterior, retrosternal, or parasternal: through the foramen of Morgagni (Figs. 38.8 and 38.9) Peritoneopericardial Acquired hernia Hiatal: sliding or fixed Paraesophageal Acquired eventration: caused by phrenic nerve injury and paralysis Traumatic (Fig. 38.10) Pelvic Wall and Floor Hernias Sciatic hernia (Fig. 38.11) Protrusion of the peritoneal sac and contents through the greater or lesser sciatic foramen Obturator hernia (Fig. 38.12) Protrusion of preperitoneal fat or intestine through the obturator foramen Perineal hernia Protrusion of a viscus through the pelvic floor (rare) Prolapse Weakness of the pelvic floor muscles can cause a cystocele, rectocele, and uterine or rectal prolapse Intraabdominal Hernias Spontaneous    Transmesenteric hernia Through the sigmoid mesocolon, broad ligament, or falciform ligament  Transomental hernia Hernia beneath a mesenteric or peritoneal fold (no disruption of the peritoneum) Locations:

Postoperative Transmesenteric and transomental hernias are most common, especially after Roux-en-Y procedures May occur through the falciform ligament from a trocar puncture during laparoscopic cholecystectomy Retroanastomotic—may occur behind the anastomosis