Hernias are abnormal protrusions of a viscus (or part of it) through a normal or abnormal opening in a cavity (usually the abdomen). They are most commonly seen in the groin; a minority are paraumbilical or incisional. In the groin, inguinal hernias are more common than femoral hernias.
Inguinal hernias occur in about 15% of the adult population, and inguinal hernia repair is one of the most commonly performed surgical procedures in the world.[1]Approximately 800,000 mesh hernioplasties are performed each year in the United States,[2] 100,000 in France, and 80,000 in the United Kingdom.
There is morphologic and biochemical evidence that adult male inguinal hernias are associated with an altered ratio of type I to type III collagen.[3] These changes lead to weakening of the fibroconnective tissue of the groin and development of inguinal hernias. Recognition of this process led to acknowledgment of the need for prosthetic reinforcement of weakened abdominal wall tissue.
Given the evidence that the use of mesh lowers the recurrence rate,[4, 5] as well as the availability of various prosthetic meshes for the reinforcement of the posterior wall of the inguinal canal, most surgeons now prefer to perform a tension-free mesh repair. Accordingly, this article focuses primarily on the Lichtenstein tension-free hernioplasty, which is one of the most popular techniques used for inguinal hernia repair.[6, 7]
Types of hernia
An indirect hernia is defined as a defect protruding through the internal or deep inguinal ring, whereas a direct hernia is a defect protruding through the posterior wall of the inguinal canal. To put it in a more anatomic way, an indirect hernia is lateral to the inferior epigastric artery and vein, whereas a direct hernia is medial to these vessels. The Hesselbach triangle is the zone of the inguinal floor through which direct hernias protrude, and its boundaries are the epigastric vessels laterally, the rectus sheath medially, and the inguinal ligament inferiorly.[8]
An incomplete hernia is confined to the inguinal canal, whereas a complete hernia comes out of the inguinal canal through the external or superficial ring into the scrotum. Direct hernias are always incomplete, whereas indirect hernias can also be complete.
A sliding inguinal hernia is one in which a portion of the wall of the hernia sac is made up of an intra-abdominal organ. As the peritoneum is stretched and pushed through the hernia defect and becomes the hernia sac, retroperitoneal structures such as the colon or bladder are dragged along with it and thus come to make up one of its walls.
Bilateral pediatric hernias are most commonly indirect hernias and arise because of the patency of the processus vaginalis. Simple ligation of the hernia sac (herniotomy) alone is enough. Surgical treatment of indirect hernias in adults, unlike that in children, requires more than simple ligation of the hernia sac. This is because the patent processus is only part of the story. With time, the internal ring dilates, leaving an adult with what can be a sizable defect in the floor of the inguinal canal; this must be closed in addition to division or reduction of the indirect hernia sac.
A hydrocele is a commonly encountered pathology related to hernias. A communicating hydrocele is, by definition, a form of indirect hernia, albeit with an extremely small defect through which only peritoneal fluid enters the sac but no viscus (eg, omentum or bowel) comes out.
Types of hernia repair
Inguinal hernia repairs may be divided into the following 3 general types:
- Herniotomy (removal of the hernial sac only) - This, by itself, is adequate for an indirect inguinal hernia in children in whom the abdominal wall muscles are normal; formal repair of the posterior wall of the inguinal canal is not required
- Herniorrhaphy (herniotomy plus repair of the posterior wall of the inguinal canal) - This may be suitable for a small hernia in a young adult with good abdominal wall musculature; the Bassini and Shouldice repairs are examples of herniorrhaphy
- Hernioplasty (herniotomy plus reinforcement of the posterior wall of the inguinal canal with a synthetic mesh) - This is required for large hernias and hernias in middle-aged and elderly patients with poor abdominal wall musculature; the Lichtenstein tension-free mesh repair is an example of hernioplasty
Open vs laparoscopic repair
Although numerous surgical approaches have been developed to treat inguinal hernias, the Lichtenstein tension-free mesh-based repair remains the criterion standard.[1] In a Cochrane review comparing mesh to nonmesh open repair, the evidence was sufficient to conclude that the use of mesh was associated with a reduced rate of recurrence.[2]
Laparoscopic approaches are feasible in expert hands, but the learning curve for laparoscopic hernia repair is long (200-250 cases), the severity of complications is greater, detailed analyses of cost-effectiveness are lacking, and long-term recurrence rates have not been determined.[9] The role of laparoscopic inguinal hernia repair in the treatment of an uncomplicated, unilateral hernia is yet to be resolved.
Nevertheless, transabdominal preperitoneal (TAPP) or totally extraperitoneal (TEP) laparoscopic inguinal hernioplasty may offer specific benefits for some patients, such as those with recurrent hernia after conventional anterior open hernioplasty, those with bilateral hernias, and those undergoing laparoscopy for other clean operative procedures.
A 2014 meta-analysis of seven studies comparing laparoscopic repair with Lichtenstein technique for treatment of recurrent inguinal hernia concluded that despite the advantages to be expected with the former (eg, reduced pain and earlier return to normal activities), operating time was significantly longer with the minimally invasive technique, and the choice between the two approaches depended largely on the availability of local expertise.[10]
For further details on the debate over laparoscopic versus open repair, seeLaparoscopic Inguinal Hernia Repair. For information on manual reduction of hernias, see Hernia Reduction.For better hemostasis, sharp dissection is preferred to blunt dissection. This is one operation in which, as the saying goes, every red blood cell must be caught.
If a lipoma is present in the spermatic cord, as is often the case, it should be excised to reduce the bulk of the cord; cord structures, however, must be protected. Some surgeons excise the cremaster muscle fibers in the cord; others prefer not to.
With a direct hernia, the sac is not dissected and opened, as is done with an indirect inguinal hernia. Rather, it is inverted (pushed back) into the extraperitoneal space, sometimes with plication of the transversalis fascia.
Bilateral hernias can be repaired in a single procedure, especially with a Lichtenstein tension-free mesh hernioplasty. Some surgeons, however, prefer to repair only one hernia at a time, deferring repair of the other for about 4-6 weeks; this avoids the risk of bilateral infection and the higher risk of penile and scrotal edema after bilateral inguinal hernia repair.
If the hernia is irreducible or obstructed, the sac should be opened first at its fundus, before it is dissected up to its neck, to allow evacuation of toxic fluid and inspection of the bowel for ischemia. If the conventional technique, in which the sac is first completely dissected up to its neck, is followed, the ischemic bowel may slip back into the peritoneal cavity before the sac is opened at its fundus and may then be difficult to retrieve for inspection.
Ischemic bowel is blue-black and thick-walled, lacks luster, feels firm to the touch, and has no peristalsis. The bowel must be wrapped in moist warm packs, and 100% oxygen should be delivered for a few minutes. The bowel is then reassessed for viability. Any nonviable bowel will have to be resected.
Approach Considerations
Inguinal hernia repairs are of the following 3 general types:
- Herniotomy (removal of the hernial sac only)
- Herniorrhaphy (herniotomy plus repair of the posterior wall of the inguinal canal
- Hernioplasty (herniotomy plus reinforcement of the posterior wall of the inguinal canal with a synthetic mesh)
The ensuing discussion focuses primarily on the Lichtenstein tension-free mesh repair, which is an example of hernioplasty and is currently one of the most popular techniques of inguinal hernia repair.[6, 7] The Bassini, Shouldice, and darn repairs (all examples of herniorrhaphy) are also briefly discussed. The key technical point is that in the Lichtenstein tension-free repair, there is no attempt to repair the posterior wall, as is done in Bassini or Shouldice repairs; the weak posterior wall is reinforced with mesh.
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