John W. Harmon
Christopher L. Wolfgang
Definitions
A hernia is a protrusion of a viscus or part of a viscus from its normal location in the body. Clinically common hernias involve anatomic defects in the abdominal wall, typically in the inguinal, femoral, or umbilical regions or at the site of a previous surgical incision. The termventral hernia, referring to an anterior abdominal wall hernia, is often used to denote an incisional hernia. A hernia is reducible
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if its contents can be pushed back into the abdominal cavity, and incarcerated if they cannot be pushed back. Strangulation of a hernia occurs when the blood supply to the herniated tissue is compromised. All strangulated hernias are incarcerated, but incarcerated hernias may not be strangulated.
This chapter describes the more common types of abdominal hernias and discusses the role of the ambulatory practitioner in their diagnosis and treatment.
Hernias of the Groin
Inguinal Hernias
Inguinal hernias are classified as direct or indirect; about two thirds are indirect (1). Direct hernias are portions of the bowel or omentum that protrude directly through the floor of the inguinal canal to emerge through the external inguinal ring above the inguinal ligament (Fig. 97.1). Indirect hernias enter the inguinal canal through its internal ring, lateral to the inferior epigastric vessels, traverse the canal, and emerge also through the external inguinal ring (Fig. 97.1). Indirect hernias, as they get larger, have a propensity to extend into the scrotum.
Epidemiology and Causes
Inguinal hernia is a common problem in ambulatory practice and accounts for approximately 75% of all abdominal wall hernias. Inguinal hernia repair is one of the most common general surgical procedures performed in the United States (1). The majority of inguinal hernias occur in men (1); 5% to 10% of men in the United States develop an inguinal hernia during their lifetime. Although femoral hernias (discussed later) are much more common in women than in men, the most common groin hernia in women is an indirect inguinal hernia. Less than 10% of inguinal hernias in adults are bilateral when the patient is first seen, but a hernia may occur on the opposite side at some time in the future. The chance of developing a contralateral inguinal hernia is the same regardless of which side is affected first.
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FIGURE 97.1. Artist's rendition of groin region, illustrating indirect and direct inguinal hernias and femoral hernia. (Modified from Dunphy JE, Botsford TW. Physical examination of the surgical patient. 3rd ed. Philadelphia: WB Saunders, 1964:118. ) |
All indirect inguinal hernias are caused by a congenital defect in which the processus vaginalis remains patent. The processus vaginalis is a tract lined with peritoneum that extends from the peritoneal cavity into the scrotum in the male. With time this tract may enlarge, and abdominal contents may herniate into it. The combination of this congenital abnormality and a predisposing acquired condition that increases intra-abdominal pressure (e.g., obesity, chronic obstructive airway disease, ascites, chronic constipation with straining at stool, prostatism with straining at urination, hard physical labor) determines when an inguinal hernia develops. Occasionally, only intra-abdominal fluid gravitates into the scrotum, causing scrotal swelling when the patient is upright but draining back into the abdominal cavity when the patient is supine. Such a lesion is called a communicating hydrocele; it is more commonly seen in children than in adults. Indirect hernias, because they are associated with a congenital defect, develop in younger people but increase in incidence with advancing age; they are about four to five times more common after 50 years of age than before.
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Direct inguinal hernias are acquired lesions and are influenced not only by changes in intra-abdominal pressure but also by progressive attenuation of the inguinal structures as part of the normal aging process. Rarely, inherited defects in collagen synthesis (e.g., Marfan syndrome) provide an obvious explanation for accelerated weakening of these structures. Direct hernias are predominantly problems of middle-aged and elderly people.
History
Most patients complain of a dull ache in the groin and a bulge, either localized to the groin or at times extending into the scrotum in men or the labia in women. Sometimes pain precedes discovery of the mass by some months (perhaps because, in early stages of herniation, the internal canal is stretched before omentum or bowel manifests as a bulge at the external inguinal ring). Occasionally, the patient recalls a sharp pain during a strenuous event, which represents the initial herniation. Often the patient or the clinician notices a herniated mass in the absence of pain or symptoms. Small reducible hernias may be noticed intermittently, at times of increased intra-abdominal pressure.
If a hernia incarcerates, it may become more painful, although many patients with chronically incarcerated hernias are pain free. Indirect hernias have an approximately 10% chance of incarcerating; direct hernias incarcerate only rarely. Essentially all strangulated hernias are symptomatic; with strangulation, the hernia becomes extremely painful and tender, and nausea, vomiting, abdominal distention, constipation, and fever (with leukocytosis) are common.
Physical Examination
The examination should be performed with the patient standing and then again with the patient recumbent. An indirect hernia sometimes can be distinguished from a direct hernia by inspection. An indirect hernia, once it has entered the inguinal canal, manifests as an elliptical swelling descending toward or even into the scrotum (Fig. 97.2). A direct hernia manifests as an isolated oval swelling near the pubis; it is rarely found in the scrotum (Fig. 97.3). If the hernia is visible, an attempt should be made to push it back the abdominal cavity. If the hernia cannot be reduced, the patient should be asked to lie down and another attempt should be made to reduce it. Approximately 10% of inguinal hernias are incarcerated when they are first diagnosed.
If the hernia is not visible, the physician's finger should be placed at the base of the scrotum and then gently advanced cephalad and laterally into the inguinal canal (Fig. 97.4). The external ring can be examined without causing the patient a great deal of discomfort. The size of the ring, in itself, does not predict the presence of a hernia or the propensity to develop one, because the external ring is an opening in the aponeurosis of the external oblique muscle that does not contribute to the integrity of the floor of the inguinal canal. When the examining finger has been directed through the external ring, having the patient increase intra-abdominal pressure by coughing or straining causes a hernia to protrude and to be felt as an impulse or bulge at the tip of the examining finger.
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FIGURE 97.2. Indirect inguinal hernia. Swelling is oblique and cylindrical and extends into the scrotum. (From Zimmerman LM, Anson BJ. Anatomy and surgery of hernia. 2nd ed. Baltimore: Williams & Wilkins, 1967:155. ) |
An attempt should be made to reduce an incarcerated hernia; however, if strangulation is suspected, as when a patient presents with severe pain associated with a pre-existing hernia, one should not attempt to reduce the hernia forcefully, because this maneuver carries the risk of
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reducing gangrenous bowel from within the hernia sac into the general peritoneal cavity. A strangulated hernia must be repaired promptly. An incarcerated hernia that is symptomatic should also be repaired on presentation, whereas the hernia of an asymptomatic patient presenting with a chronic incarceration can be fixed electively.
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FIGURE 97.3. Direct inguinal hernia. Note medially situated globular swelling. (From Zimmerman LM, Anson BJ. Anatomy and surgery of hernia. 2nd ed. Baltimore: Williams & Wilkins, 1967:154. ) |
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FIGURE 97.4. Examination of the inguinal canal. The examining finger gently invaginates the scrotum into the inguinal canal. (Modified from Dunphy JE, Botsford TW. Physical examination of the surgical patient. 3rd ed. Philadelphia: WB Saunders, 1964:116. ) |
Differential Diagnosis
The most common cause of groin pain that is mistaken for a hernia is strain of the adductor muscles of the thigh at their attachment to the pelvis. Because, like groin hernia, the onset of this symptom is related to physical labor, both the patient and the clinician are convinced that a hernia must be present. In the absence of appropriate physical findings, the temptation to surgically explore the groin must be firmly resisted. As with other muscular injuries, groin strain can take months to resolve.
An incarcerated scrotal hernia must be distinguished from other scrotal lesions (Fig. 97.5). One of the most common of these is a hydrocele—a tense, slightly fluctuant mass that can be distinguished from a hernia or a solid mass by transillumination. Another common scrotal mass is a varicocele—an enlarged venous plexus that on palpation feels soft and worm-like and extends from the testicle up toward the spermatic cord. It does not transilluminate and, when the patient lies down, it collapses. If a varicocele is of recent onset in an adult, occurs on the left, and does not disappear in the supine position, one must consider obstruction of the left spermatic vein (which enters the left renal vein) by a retroperitoneal neoplasm. A spermatocele is a localized but vaguely circumscribed mass that also does not transilluminate and that persists when the patient lies down.
Apart from distinguishing a hernia from another kind of scrotal mass, an important component of the physical examination is the examination of the testicle and its surrounding structures. In that way, epididymal cysts, epididymitis, orchitis, testicular torsion, and testicular tumors can be detected. Epididymal cysts can occur in any portion of the epididymis and may be smooth or lobulated; some of them transilluminate; they are innocuous and require no treatment. Epididymitis manifests as a tender, swollen epididymis (see Chapter 37). Often, elevation and immobilization of the scrotum relieve the pain associated with an inflammatory process. In contrast, the pain produced by torsion of the testicle is unremitting. Sudden onset of testicular pain in an otherwise healthy person is characteristic of this problem. On examination, the testicle is enlarged and exquisitely tender. The patient should be referred immediately to a general surgeon or urologist. Testicular tumors can involve the entire testicle or simply protrude as a small nodule from the testicular surface. These masses are more indurated than the common benign scrotal masses, and they usually lack the slight tenderness of the normal testicle. Patients with suspected tumors should be referred as soon as possible to a urologist.
Preoperative Evaluation of the Patient with a Hernia
When evaluating a patient with a hernia, it is important to consider whether coexistent disease has allowed the hernia to manifest at that point in time. Focused questions in the medical history should include a specific inquiry about smoking, a history of cough, difficulty urinating, or difficulty with bowel movements, including straining and constipation. A rectal examination, to assess for the presence of prostatic hypertrophy or a rectal mass, is an important part of the preoperative evaluation. The examiner should also ascertain whether ascites is present. Anything that increases intra-abdominal pressure will place tension on the endoabdominal fascia and may contribute to the development or presentation of a hernia. A practitioner would not want to miss a diagnosis of lung cancer, prostate cancer, or colorectal cancer when referring a patient for
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hernia repair. Furthermore, attention to any predisposing causes of increased intra-abdominal pressure may limit the effect these conditions have on hernia recurrence rates.
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FIGURE 97.5. Lesions palpable in the scrotum. A correct diagnosis can usually be made if the normal anatomic relationships of the contents of the scrotum are borne in mind. (Modified from Dunphy JE, Botsford TW. Physical examination of the surgical patient. 3rd ed. Philadelphia: WB Saunders, 1964:111. ) |
Management
Almost all inguinal hernias should be repaired. Severe coexistent illness is the only real contraindication to herniorrhaphy (see Chapter 93for a discussion of anesthesia and
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surgery risks in patients with coexistent medical conditions). Although no sense of urgency is associated with elective repair, it should be recognized that the risk of incarceration or of strangulation is greater with indirect than with direct hernia. Accordingly, the repair of a direct hernia may be more confidently deferred, or even declined, in the face of a significant medical illness. Nonoperative therapy should be discouraged; the wearing of a truss is potentially dangerous and does not guarantee that a hernia will remain reduced. Also, the pressure of the truss on the margin of a large defect eventually leads to atrophy of the fascial and aponeurotic (broad tendinous) layers, causing the hernia to enlarge. Subsequent repair is more difficult and therefore carries a greater risk of recurrence.
Elective herniorrhaphy prevents acute incarceration (and strangulation) and the need to perform an emergency operation. If the hernia is chronically incarcerated and there are no symptoms of strangulation (strangulation is primarily a risk in acutely incarcerated, small, indirect hernias), repair may be scheduled electively. If the hernia has incarcerated acutely, the patient must be hospitalized and attempts made to reduce the hernia before operation. A short period of bed rest, combined with an analgesic and an ice pack will often result in reduction of a hernia. Strangulated hernia is a true surgical emergency, because delay in treatment can lead to gangrene of the intestine or omentum. Suspected strangulated hernias require immediate operative intervention.
Bilateral hernias may be repaired at one operation or as staged procedures, depending on their size, the type of repair required, the age of the patient, and coexistent medical conditions. If the patient is elderly and the hernias are large and require complex repair, herniorrhaphies should be staged 4 to 6 weeks apart. Bilateral repairs of indirect inguinal hernias in children or young adults are routinely done at one operation.
Currently, most unilateral inguinal hernias are repaired through a 6- to 8-cm incision under local or regional anesthesia as an outpatient procedure. Many surgeons routinely use prosthetic mesh during the repair. The patient is rarely uncomfortable during the operation. Epidural, spinal, or general anesthesia is used for patients who cannot tolerate the procedure under local anesthesia, patients with large hernias requiring complex repair, and obese patients, in whom repair of the hernia under local anesthesia is technically difficult. Bilateral inguinal herniorrhaphy may also require epidural, spinal, or general anesthesia. Repair of hernias in children is usually done with the patient under general anesthesia.
Laparoscopic Herniorrhaphy
Laparoscopic (or minimally invasive) surgery has lost popularity in the treatment of groin hernias based on poor results in a large Veterans Administration multicenter trial (2). General anesthesia is required for laparoscopic repair, but is often not necessary with an open technique. A laparoscope and two or three instruments are introduced into the peritoneal cavity, usually through separate 0.5- to 1.0-cm incisions rather than one long incision. Under direct visualization, indirect hernia sacs can be dissected and even large defects can be repaired with the use of prosthetic mesh. The cost of laparoscopic repair at this time is significantly higher than that of open repair. Although laparoscopic repair is an accepted technique particularly for bilateral inguinal hernias, the predominant approach still remains the traditional open anterior repair.
Course and Recovery
No matter which anesthesia or technique is used, certain complications of herniorrhaphy are possible (in approximately 7% of patients): recurrence (the most common complication), urinary retention, wound infection, hydrocele formation, femoral or ilioinguinal neuralgia, scrotal hematoma, and, rarely, unilateral testicular atrophy. The primary caregiver and the surgeon should discuss these complications with the patient before the operation and provide assurance that, except for recurrence of hernia (and uncommonly testicular atrophy), they are usually transient problems.
When patients are discharged from the hospital, they are ambulatory but typically require narcotic analgesics for relief of pain. For the first week, the patient is advised to avoid lifting or straining and to use a stool softener and a mild laxative. The patient can return to light work (and light activity such as long walks) within another 2 weeks, but an occupation that requires heavy lifting or considerable exertion requires a total convalescence of 6 weeks.
Driving a car during the first 2 weeks should be discouraged, not because it is a form of strenuous activity, but because the patient, fearing pain or injury, may not step on the brake vigorously enough or soon enough in a crisis to avoid a collision. Sexual activity should be avoided for the first 3 weeks after surgery. Resumption of normal recreational and work activities requires common sense. Most patients are fully rehabilitated and working less than 1 month after herniorrhaphy. Because recurrence may be related to premature untoward exertion, patients must be cautioned to avoid strenuous activity for 6 weeks.
Approximately 1% to 7% of indirect and 4% to 10% of direct inguinal hernias recur. More than 50% of the recurrences occur within 5 years after the initial repair. The recurrence rate after repair of a recurrent hernia is even higher, ranging from 5% to 35%. Most surgeons use mesh in the repair of recurrent hernias.
Femoral Hernias
Epidemiology and Causes
A femoral hernia is a protrusion of omentum or bowel through the femoral canal (Fig. 97.1). It is much more
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common in women than in men, although the indirect inguinal hernia is still the most common hernia in women. The incidence increases with increasing age, presumably because of the degradation of collagen and attenuation of tissue that accompanies aging. It is likely, however, that a contributing cause of a femoral hernia is a congenitally large femoral ring. Preperitoneal fat, forced through the large ring, enlarges it further. Increased pressure produced by straining or pregnancy undoubtedly contributes to femoral herniation. Femoral hernias are bilateral in at least 15% of cases. The risk of incarceration, and particularly of strangulation, is especially high with this type of hernia.
History
The primary symptom of a femoral hernia is a bulge in the groin. A dull pain may be experienced, but less commonly than in patients with an inguinal hernia. Approximately 20% of femoral hernias incarcerate (twice the rate of indirect inguinal hernias). The symptoms of incarceration and strangulation are the same as in patients with inguinal hernias.
Physical Examination
A mass is often palpable, medial to the femoral vessels and inferior to the inguinal ligament. The mass is usually reducible, and occasionally it is tender. Despite careful examination, the hernia often is difficult to detect, especially in obese women, even if it is incarcerated or strangulated. Therefore, women with signs and symptoms of unexplained intestinal obstruction should be examined carefully for evidence of a strangulated femoral hernia.
Differential Diagnosis
A femoral hernia must be distinguished from an enlarged lymph node, a lipoma, a saphenous varix, and a direct inguinal hernia. The first three of these possibilities are not reducible. A lymph node or lipoma may not transmit an impulse to the examiner's finger when the patient coughs. A saphenous varix may simulate a hernia impulse, however, because increased venous pressure induced by the Valsalva maneuver is transmitted to the varix. A lymph node or lipoma is more movable than a hernia, and a varix can be collapsed by compression of the saphenous vein. The distinction between a femoral and other groin hernias sometimes can be made only at operation.
Management and Course
Femoral hernias should be repaired unless the patient is unable to tolerate an operation. The increased risk of incarceration and strangulation adds to the urgency of the recommendation. The operative and postoperative considerations for inguinal hernias (discussed earlier) apply to femoral hernias as well, except that, for technical reasons, a larger proportion of femoral hernias may have to be performed under spinal or general anesthesia, usually as outpatient procedures. Laparoscopy (see earlier discussion) can also be used in femoral hernia repair. Between 1% and 7% of femoral hernias recur and, as with inguinal hernias, 5% to 35% of repaired recurrent hernias also recur.
Umbilical Hernias
An umbilical hernia is a protrusion of omentum or bowel through the umbilical ring. These hernias are probably caused by congenital defects. Among adults, they appear most often in middle-age multiparous women, in patients with cirrhosis of the liver and ascites, and in frail elderly people. They are also common in infants. Most umbilical hernias are obvious as an enlargement of the umbilical ring with protrusion of intra-abdominal contents through it. However, a few patients complain only of vague intermittent pain and tenderness in the region of the umbilicus. On examination, a small defect is usually found that contains a small piece of omentum, preperitoneal fat, or a knuckle of bowel. If patients are placed in the supine position and then asked to raise their head and cough, the hernia can be palpated.
The most common complication of umbilical hernia is incarceration with or without strangulation. Incarceration is more common with umbilical hernias than with groin hernias. For that reason, unless the patient cannot tolerate an operation, all umbilical hernias in adults should be repaired. Morbidity and mortality from such an operation are much lower if it is performed electively rather than in response to acute incarceration or strangulation. The only exception to this recommendation is umbilical hernias in infants. These tend to close spontaneously as the child gets older, and repair should be deferred until school age.
The repair may be done under local anesthesia if the hernia is small; otherwise, general or spinal anesthesia is preferred. The use of mesh to reinforce the repair is being tried as a strategy to reduce recurrence rates. Laparoscopic repair is also an option, but it is not of proven benefit.
Epigastric Hernias
An epigastric hernia is a protrusion of fat or omentum through the linea alba between the umbilicus and the xiphoid cartilage. These hernias almost never contain a viscus. A congenital defect in the linea alba is probably the major disposing factor. Epigastric hernias most commonly appear between the ages of 20 and 50 years and are three times more common in men than in women. Most patients complain of a small, painless, subcutaneous mass, most often just to the left of the midline. Usually the hernia consists of preperitoneal fat or fat of the falciform ligament.
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Larger defects also contain omentum. Complications are more common in patients with small hernias because these are more likely to incarcerate. When this happens, there is usually local pain and tenderness and, less often, deep epigastric pain, abdominal distention, and nausea and vomiting. All epigastric hernias should be repaired, usually as outpatient procedures. The recurrence rate after epigastric herniorrhaphy is approximately 10% and usually can be attributed to failure to appreciate multiple defects in the linea alba at the time of the initial operation.
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FIGURE 97.6. Large postoperative (ventral) hernia after cholecystectomy. (From Zimmerman LM, Anson BJ. Anatomy and surgery of hernia. 2nd ed. Baltimore: Williams & Wilkins, 1967:287 .) |
Incisional Hernias
An incisional hernia is the protrusion of omentum or bowel through a fascial defect at the site of a prior surgical incision. Unlike the other types of abdominal hernia, a congenital weakness of the abdominal wall does not contribute to the development of the hernia. Any abdominal incision may be the site of a hernia. The major risk factors leading to the development of an incisional hernia are wound infection and obesity. With the increasing use of chronic ambulatory peritoneal dialysis to treat patients in chronic renal failure (see Chapter 52), it has become apparent that incisional hernias (as well as inguinal hernias) are particularly common in this group of patients.
The hernia usually manifests as a bulge through the incision that may enlarge if neglected (Fig. 97.6) and may even lead to intestinal obstruction. It should be repaired electively once the diagnosis is made in order to avoid the development of a larger defect that will complicate repair and be more likely to recur. If possible, an obese patient should lose weight before the operation (see Chapter 83). Laparoscopic repair for these hernias is used in some centers but it is not of proven benefit. The long term recurrence rates are unknown. Prosthetic mesh is commonly employed to repair incisional hernias. In using mesh, effort is taken to avoid exposure of the viscera to coarse textured mesh, which may lead to bowel obstruction or fistula. Instead, the surgeon interposes peritoneum or biodegradable mesh between permanent mesh and underlying viscera. Repaired incisional hernias have a much higher recurrence rate than do other kinds of abdominal hernias. Many patients with incisional hernia have significant comorbidity from underlying medical conditions, which must be taken into account when considering surgery.
For repair of recurrent hernias, advanced techniques include component separation to transfer muscle and fascia to close large defects, and allogeneic keratinocyte grafts (Apligraf) from unrelated donors that may resist infection better than traditional mesh materials (Marlex or Gore-Tex).
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Diastasis Recti
Diastasis recti refers to wide separation of the rectus abdominus muscles in the midline, with attenuation of the linea alba. It is not a true hernia. Patients may present with an asymptomatic midline linear bulge that protrudes when the patient strains and is more predominant in the epigastrium. This is usually mistaken for a hernia and can be quite large. On examination, however, there is no scar indicating a prior incision, and there is no palpable fascial defect. Surgical correction of diastasis recti is not required, because this condition is rarely symptomatic and carries no risk of visceral incarceration because the fascia remains intact. Patients who are concerned about the appearance of the abdominal wall can be counseled or referred for cosmetic surgery.
Specific References
For annotated General References and resources related to this chapter, visit http://www.hopkinsbayview.org/PAMreferences.