Approach to the Patient with an External Hernia

James M. Richter

Abdominal wall hernias are exceedingly common; they often cause occupational disabilities and pose a risk for incarceration and strangulation of bowel. Fortunately, adequate evaluation can usually be performed in the office by means of history and physical examination. The primary physician must distinguish between patients who require surgical referral and those who may be managed expectantly.

PATHOPHYSIOLOGY AND CLINICAL PRESENTATION (1,2)

Pathophysiology

A hernia is a defect in the musculofascial continuity of the abdominal wall that permits the internal organs to abnormally pass through. In general, the significant feature of a hernia is not the size of the protrusion or the sac, but the size and rigidity of the defect in the abdominal wall. The fixation and rigidity of the hernial ring are the features that lead to incarceration and strangulation. The distinction between congenital and acquired hernia is not often clear because many hernias that appear after trauma or straining represent a congenital predisposition, such as indirect inguinal hernia in the adult. This distinction has little bearing on management, although it can make a considerable difference to the patient, who may be compensated if the hernia can be attributed to trauma at work. Some of these hernias are incidental to, and antedate, the perceived injury.

Disorders resulting in increased intra-abdominal pressure may contribute to the appearance of a hernia and also affect the postoperative management. For example, chronic cough resulting from cigarette smoking or bronchitis can precipitate or worsen herniation; the same is true of symptomatic prostatism.

Clinical Presentations

Reducible Hernia

The symptoms of an uncomplicated or reducible external hernia are related not to its size but to the degree of pressure on its contents. Patients with large scrotal hernias containing much intestine may have few symptoms other than a dragging sensation. A mass appears on standing, which reduces when the patient is supine. Pain may be intermittent, disappearing when the hernia is reduced. Patients with small hernias containing an entrapped knuckle of bowel may have rather severe pain and nausea. Many patients with femoral, umbilical, or epigastric hernias may be entirely unaware of their existence.

Irreducible or Incarcerated Hernia

Irreducible or incarcerated hernia is one in which the contents cannot be replaced into the abdomen. Here, the mass remains palpable with the patient relaxed and in the supine position. A strangulated hernia is an irreducible hernia in which the blood supply to the entrapped bowel loop has been compromised, resulting in small-bowel obstruction and infarction. These patients complain of colicky abdominal pain, nausea, and vomiting and show signs of small-bowel obstruction with distention, tympany, and hyperperistalsis. In addition, careful examination demonstrates a tender, irreducible groin or ventral hernia.

Inguinal Hernias

Indirect inguinal hernias, which account for one half of all hernias in adults, pass through the internal abdominal inguinal ring along the spermatic cord through the inguinal canal and exit through the external inguinal ring. In male patients, these can descend into the scrotum. Direct inguinal hernias pass through the posterior inguinal wall medial to the inferior epigastric vessels, through Hesselbach triangle. Femoral hernias pass through the femoral canal inferior to the inguinal ligament and become subcutaneous in the fossa ovalis. It is often difficult to distinguish among these three forms, especially when incarceration is present and the sac is large.

Indirect inguinal hernias are eight to ten times more common in men than in women, whereas femoral hernias are three to five times more common in women than in men. Nevertheless, the most common hernia in women is the indirect inguinal type. The diagnosis is less often made in women because physical examination of the external inguinal ring is more difficult. Direct hernias increase in incidence with advancing age and are the least likely of the external hernias to become incarcerated or strangulated.

Strangulation is common in femoral hernias. The majority of patients with strangulated inguinal hernias are aware of the hernia before strangulation. In contrast, nearly half of those with strangulated femoral hernias are unaware of the hernia before strangulation. In addition, groin pain and tenderness are absent in a significant percentage of cases of strangulated femoral hernia.

Ventral Hernias

The commonly encountered ventral hernias include umbilical, epigastric, and incisional varieties. Ventral hernias are often more obvious when the patient is standing. Umbilical hernias pass through the umbilical ring and represent a failure of the ring to be obliterated after birth. In the infant, these often close spontaneously within the first 2 years of life. In the adult, they are more common in women and are associated with obesity, multiparity, and cirrhosis with ascites. Umbilical hernias are often missed because they are obscured by subcutaneous fat. They are associated with a high risk for incarceration and strangulation, and mortality rates are higher than with inguinal hernias because the large bowel is frequently entrapped.

Incisional Hernias

Incisional hernias are those that develop in the scar of a previous laparotomy or in a drain site. They are associated with a previous postoperative wound infection, dehiscence, malnutrition, obesity, and smoking. They are more common in vertical than in transverse scars. Incisional hernias often have multiple defects and several rings. They are frequently irreducible or only partially reducible because of adhesions within the sac. Patients with very large incisional hernias may be remarkably free of symptoms of intestinal obstruction, although incarceration is not uncommon (6% to 15%); strangulation is relatively uncommon (2%) because of the usually large size of the defects.

Epigastric Hernias

Epigastric hernias occur through the linea alba between the xiphoid process and the umbilicus. They may be difficult to detect in the obese patient and must be looked for in patients with epigastric pain. Incarcerated epigastric hernia may produce symptoms that mimic those of peptic ulcer disease or biliary colic.

DIFFERENTIAL DIAGNOSIS (1)

Recognizing a hernia usually presents little difficulty, although distinguishing one type of inguinal hernia from another can sometimes be complicated. The differential diagnosis of an entrapped femoral hernia includes not only inguinal hernia but also femoral lymphadenopathy, saphenous varix, psoas abscess, and hydrocele. On occasion, it is impossible to differentiate an incarcerated femoral hernia from a single enlarged femoral lymph node (the lymph node of Cloquet). Other causes of groin pain or swelling include muscle strain, hip arthritis, inguinal adenopathy, and undescended testicle. Diastasis recti (a separation between the left and right side of the rectus abdominis muscle) may mimic a ventral hernia, but there is no identifiable hernia fascial defect.

WORKUP (1,2)

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