Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Abdominal Wall and Abdominal Cavity Hernias
The word “hernia” derives from the Greek hernios, which means “bud.” It indicates a protrusion of organs through an abnormal defect (opening) in a natural cavity, being the opening, the key part of the definition. In fact, the protrusion may not be recognized in some patients early in the process. The neck of the hernia sac corresponds to the hernial orifice. The dimension of the neck and the volume of the distended sac determine the size of the hernia. The hernia type depends on its location and cause, the mobility of the herniated organ, and the status of the blood supply ( Fig. 48.1 ).
Indirect and Direct Inguinal Hernias.
Approximately 20% of males and 0.2% of females acquire hernias during their lifetime. Hernias of the abdominal wall occur only where aponeurosis and fascia are devoid of the protecting support of striated muscle. Some may be acquired through muscular atrophy or surgery. Common sites of herniation are the groin, umbilicus, linea alba, semilunar line of Spiegel, diaphragm, and surgical incisions. Other similar but rare sites of herniation are the peritoneum, superior lumbar triangle of Grynfeltt, inferior lumbar triangle of Petit, and obturator and sciatic foramen of the pelvis.
Inguinal Hernias
Inguinal hernias are by far the most common type of hernia. The highest incidence is during the first year of life, with a second lower peak between ages 16 and 20. The lifetime risk of developing an inguinal hernia is 27% for men and 3% for women. In both men and women, most inguinal hernias are indirect. The hernial sac is generally composed of peritoneum and attenuated layers of the abdominal wall. The ring is the actual defect and sometimes is the only abnormality palpable on physical examination. The contents may vary in different parts of the large and small intestines, bladder, ovaries, and omentum. The proximal part of the sac is the narrowest and is therefore called the neck, and the distal part is the fundus.
Indirect Inguinal Hernias
Failure of obliteration of the funicular process or processus vaginales during the third trimester of pregnancy leaves a channel open for the formation of an indirect inguinal hernia. However, it does not necessarily imply the development of a hernia; other factors play a role in permitting intraabdominal structures to enter this sac.
On the other hand, the disparity between intraabdominal pressure and resistance of the muscular and fascial structures forming the deep inguinal ring may also explain the origin of the defect. Great examples of this setting are conditions such as pregnancy, ascites, and prolonged coughing in patients with pulmonary emphysema and trauma.
Anatomically, the sac is anterosuperior to the spermatic cord in indirect hernias, and the deep inferior epigastric vessels are displaced medially. In addition, the protrusion of the sac and the widening of the deep ring alter the relationship between the two inguinal rings, which begin to lie perpendicularly.
Direct Inguinal Hernias
Direct inguinal hernias have a different pathophysiologic mechanism than indirect hernias. Although it is considered an acquired condition, with peak prevalence in men age 40 to 50, a congenital developmental abnormality has been identified where the fibers of the lower internal oblique muscle seem to be arranged in a transverse rather than an oblique configuration. Consequently, the conjoint tendon is attached to the rectus muscle at a more superior level, facilitating the formation of a hernia. The protrusion is characteristically medial to the deep epigastric vessels through the posterior wall of the inguinal canal.
Clinical Picture
The spectrum of inguinal hernia symptoms ranges from none to bowel strangulation. In states of rest or recumbency, most hernias are asymptomatic. Physical activity and especially increased intraabdominal pressure elicit symptoms of fullness, pain, or simply a bulge. Occasionally, symptoms may be attributed to the specific organ involved (dysuria in bladder, constipation for sigmoid colon). Predisposing factors to direct hernia include chronic increase in intraabdominal pressure (obesity, ascites, chronic cough, constipation, occupational or recreational weight lifting) and atrophy of the abdominal wall musculature (malnutrition, aging). Usually, symptoms are subtler with direct inguinal hernias.
Diagnosis
History taking and physical examination confirm the diagnosis of hernia. The examination should be conducted with the patient in the supine and upright positions. With the examiner's finger gently invaginating the scrotal skin and covering the superficial ring, the patient is encouraged to abruptly increase abdominal pressure (Valsalva maneuver, cough).
For smaller hernias, especially in women and children, inspection is often more valuable than palpation. Physical examination is more difficult in infants, but a thickened cord at the superficial ring is a reliable sign of hernia, especially if it is unilateral. When a left-sided inguinal hernia develops in a child, there is a 50% chance of bilaterality; however, this does not seem to be true for a right-sided inguinal hernia.
It is important to establish that when the scrotum is swollen ipsilaterally, the clinician must consider the presence of another abnormality such as hydrocele, varicocele, or testicular mass.
Computed tomography (CT) scan of the abdomen can aid the clinician to identify symptomatic inguinal hernias that are otherwise not palpable.
Treatment and Management
Surgery has become the preferred approach for patients of all ages. Surgery for inguinal hernia repair is simpler in infants than in adults. In fact, the proximity of the deep and superficial inguinal rings makes the opening of the aponeurosis of the external oblique muscle unnecessary and dangerous for the cord structures. Isolating the sac is more difficult in female infants because of the smaller size of the sac, in turn making it more difficult to identify anterior to the round ligament.
Numerous surgical techniques have been described. Bassini in Italy and Halsted in the United States established the fundamental principles at the end of the 1800s.
Bassini repair is one of the cornerstones in the evolution of inguinal hernia repair. It involves approximation of the internal oblique, transversalis fascia, and transversus abdominis muscle complex to the inguinal ligament and the ileopubic tract to reinforce the posterior wall of the inguinal canal. Halsted repair is almost identical to the Bassini procedure, except for the subcutaneous position of the cord structures and the addition of an extra layer (external oblique aponeurosis) to the repair. This resulted in a high incidence of testicular ischemia and hydrocele, so Halsted modified the original technique, leading to the Halsted II or Ferguson-Andrews procedure.
In 1898 Lotheissen described using the iliopectineal, or Cooper, ligament rather than the inguinal ligament to anchor the triple layer (internal oblique, transversalis fascia, and transversus abdominis muscle) of the Bassini repair. McVay and Anson added, 40 years later, a relaxing incision in the rectus sheath to avert tension. The external oblique was then closed over the cord. This variation has since become more widely used than the Bassini repair, especially for repair of direct hernias.
Treatment of direct hernia is primarily surgical, and multiple techniques have been described. With lason repair, the incision is made over the protrusion and is extended to the superficial inguinal ring. The actual repair is accomplished by suturing the conjoint tendon to the inguinal or pectineal ligaments, and the external oblique aponeurosis is imbricated above or below the cord.
Since the introduction of synthetic meshes in the 1950s, interest in the application of tension-free repair (e.g., Lichtenstein) in inguinal hernias increased exponentially. Initially used to reinforce conventional repairs, the Marlex mesh was then extended to patients with more challenging hernias, such as large direct or recurrent hernias. The infection rate was reportedly less than 2%, and the recurrence rate was approximately 6%. Later, the primarily repair with a tension-free onlay prosthetic mesh was introduced. Advantages of this technique included decreased postoperative pain, lower recurrence rates, faster return to work and normal activity, and a shorter learning curve than for conventional repairs. Although the possibility of infection was still a concern, subsequent trials failed to show a higher incidence of infection using mesh; they have rather shown a reduced rate of recurrence and likelihood of long-term pain.
Laparoscopic repair was introduced in the early 1990s. Its main advantages were less postoperative pain and more rapid to return to work compared with previous techniques. In addition, laparoscopic hernias present the unique advantage of allowing for bilateral repair during the same operation. The main indications for laparoscopic repair are for bilateral and recurrent hernias. Among the various techniques described, only transabdominal preperitoneal (TAPP) and total extraperitoneal (TEP) repairs remain popular laparoscopic options. The main difference between them is the approach to the preperitoneal space. With the transabdominal preperitoneal repair, the transversalis fascia is exposed by way of the intraperitoneal route, whereas with total extraperitoneal repair, the dissection is entirely preperitoneal.
Currently there is an additional option for repair available, the robotic-assisted technique. Da Vinci (Intuitive Surgical, Sunnyville, CA) introduced their device into the market in 2000. Since that time, urology and gynecology have mainly used this technology for deep pelvic dissections. The robotic platform has now been used in general surgery and it is used for many abdominal wall hernia repairs, including the inguinal hernia. In a method similar to the TAPP laparoscopic technique, the robot can be docked and the instrument used to reduce the hernia, implant mesh, and close the peritoneal defect. Similar results to the laparoscopic approach are seen in the hands of surgeons trained in and familiar with robotic surgery.
Femoral Hernias
Femoral hernias are those in which the abdominal viscera protrude through the femoral ring ( Fig. 48.2 ). In most patients a hernia sac is present. These types of hernias are usually unilateral, with a right-sided predominance. Femoral hernias are three times more common in females, although the overall incidence is much lower than for inguinal hernias.
Despite the true etiology of femoral hernia being unknown, two theories have been postulated. The first one states that these hernias are congenital and derived from a preformed sac. This is supported by the findings of femoral hernias in fetuses. Conversely, the second theory hypothesizes that the increased intraabdominal pressure plays a key role in acquiring this type of defect, explaining the higher incidence of femoral hernias in older, multiparous women and also the embryonic peritoneal protrusion being different from the hernial sac.
Pathophysiologically, the boundaries of the femoral canal are the cribriform fascia and the inguinal ligament anteriorly, the fascia lata over the pectineus muscle and Cooper ligament posteriorly, the femoral vein laterally, and the lacunar (Gimbernat) ligament medially.
The herniating viscus pushes a peritoneal sac and some preperitoneal fat tissue behind the inguinal ligament and through the inguinal ring. It then emerges in the subcutaneous tissue at the level of the fossa ovalis. At this point, the herniated viscus can extend upward to the level of the inguinal hernia. However, the neck is always below the inguinal ligament and lateral to the pubic tubercle. For this reason, a femoral hernia can be mistaken for an inguinal hernia, making reduction difficult if pressure is applied directly upward and toward the superficial ring. The sac may descend anterior to the femoral vessels (prevascular hernia) or behind the vessel (retro vascular hernia). When an aberrant obturator artery is present, the sac may be bisected (bilocular).
Clinical Picture
Femoral hernias are usually small and produce minimal symptoms until they become incarcerated or strangulated. Strangulation is the most common complication of femoral hernias, occurring 10 times more frequently than in inguinal hernias.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here