An indirect inguinal hernia passes through the internal (deep) inguinal ring and into the inguinal canal (Fig. 44-2). It is located lateral to the inferior epigastric vessels. During fetal development, the processus vaginalis allows descent of the testes into the scrotum. Failure of it to close before birth leads to a hernia or hydrocele.

Figure 44-2 Indirect inguinal hernia.

An indirect inguinal hernia is the most common type overall. This type of hernia occurs more frequently in males than in females and is commonly found in children and young adults. Approximately 5% of full-term infants and 30% of preterm infants will have an inguinal hernia.13,14 Incarceration occurs more commonly in patients younger than 1 year, and 30% of hernias in children younger than 3 months become incarcerated.^15,16 For incarcerated inguinal hernias in children that are successfully reduced, surgical repair within 24 to 48 hours should be considered because of the risk for recurrent incarceration.¹⁷ When an inguinal hernia is diagnosed, even without incarceration or strangulation, it is important to make a referral for elective repair. Studies have shown that even asymptomatic and painless inguinal hernias can cause symptoms over time if they are not surgically repaired,⁴ although watchful waiting may also be appropriate in some patients.¹⁸ Clinical studies demonstrate increased morbidity with emergency versus elective repair of inguinal hernias.¹⁹

Direct Inguinal Hernia

A direct inguinal hernia comes directly through the muscular and fascial wall of the abdomen. It is located within the inguinal triangle and is thus medial to the inferior epigastric vessels (Fig. 44-3). It can be differentiated from an indirect inguinal hernia in that it does not travel along the inguinal canal.

Figure 44-3 Direct inguinal hernia.

A direct inguinal hernia is the second most common groin hernia. It is an acquired hernia and occurs later in life secondary to weakening of the fascial and muscular wall as a result of aging and the repetitive stress of increased abdominal pressure. This hernia carries minimal risk for incarceration because the neck of the hernial orifice is typically wide.

Pantaloon Hernia

A pantaloon hernia is a combination of a direct and an indirect hernia and resembles the two legs of a pair of pants. This variation of an inguinal hernia is difficult to diagnose in the ED and is often discovered during surgical exploration. Successful treatment depends on correctly identifying the hernia and subsequent reduction of each “leg” of the hernia separately.

Femoral Hernia

A femoral hernia occurs inferior to the inguinal ligament through a defect in the transversalis fascia. The contents protrude into the potential space in the femoral canal located medial to the femoral vein and lateral to the lacunar ligament (Fig. 44-4). Because of the small fascial defect and constriction by the inguinal ligament, this hernia becomes incarcerated in up to 45% of cases.²⁰ A femoral hernia is relatively uncommon, occurs more frequently in women than in men, and is an uncommon condition in children.²¹

Figure 44-4 Femoral hernia.

Incisional Hernia

An incisional hernia commonly follows abdominal surgery in an area of postincisional weakness in the abdominal wall (Fig. 44-5A). Poor wound healing (e.g., because of infection) increases the likelihood of forming this type of hernia.^22,23 An incisional hernia occurs after 3% to 13% of all abdominal surgeries and carries a recurrence rate of 20% to 50%.²⁴ Because the lines of tension pull this hernia open, the size of the defect is usually sufficient to prevent incarceration.

Figure 44-5 Ventral hernias. A, Incisional hernia. B, Umbilical hernia. C, Epigastric hernia. D, Spigelian hernia.

Umbilical Hernia

An umbilical hernia traverses the fibromuscular ring of the umbilicus (Fig. 44-5B). This hernia is most commonly found in infants and children, is congenital in origin, and often resolves without treatment by the age of 5.²⁵ If the hernia persists beyond this age, is larger than 2 cm, or becomes incarcerated or strangulated, it may be repaired surgically.^19,26 An acquired umbilical hernia may also be seen in an adult, particularly with increased abdominal pressure (such as with obesity, ascites, or pregnancy). An umbilical hernia is more prone to incarceration and strangulation in an adult than in a child.

Epigastric Hernia

This hernia occurs in the midline through the linea alba of the rectus sheath (see Fig. 44-5C). It is usually located in the epigastric region between the xiphoid and the umbilicus. Though previously considered rare in infants, one study found epigastric hernias in 4% of all pediatric patients evaluated for hernias.²⁷

Spigelian Hernia

A spigelian hernia is rare and courses through a defect in the lateral edge of the rectus muscle at the level of the semilunar line (Fig. 44-5D). It is caused by a partial abdominal wall defect in the transverse abdominal aponeurosis or the spigelian fascia. Patients are typically 40 to 70 years of age, but the hernia has also been reported in younger patients.¹ Incarceration rates (often with omentum) have been reported to be as high as 20% with these uncommon hernias.^25,28 Some reports suggest that ultrasound may be a valuable adjunct for the diagnosis of these hernias and may be helpful during attempted reduction procedures.^29,30

Diagnosis

History and Physical Examination

A patient with a symptomatic hernia may seek treatment in the ED because of swelling or pain in the region of the hernia or abdomen. Ask whether the patient has a history of heavy lifting. Inquire about signs of infection and systemic illness, such as fever, chills, and malaise. Determine whether the patient has signs of bowel obstruction, including nausea and vomiting. Occasionally, the signs and symptoms of intestinal obstruction can be so prominent that the clinician does not suspect the hernia to be the culprit. Document a record of previous surgeries and hernia repairs, including the presence of synthetic mesh.

On physical examination, palpate the inguinal canal in males by inverting the scrotal skin and passing a finger into the external ring. Ask the patient to cough or perform a Valsalva maneuver, which increases intraabdominal pressure and facilitates detection of a hernia. Palpation of the external ring is more difficult in females because it is narrower. An indirect inguinal hernia is manifested as a swelling in the area of the inguinal ligament or as scrotal swelling in male patients. It is often painless and may be noted as an incidental finding. On examination this hernia can be differentiated from a direct hernia in two distinct ways. First, it begins lateral to the inferior epigastric arteries. Second, on palpation of the inguinal canal, the contents of the hernia will strike the tip of the finger instead of the pad. This occurs as the hernia protrudes down the canal to meet the finger instead of across a fascial and muscular defect. This effect can be accentuated by applying pressure over the internal ring after hernia reduction. Bulging will recur with straining if the hernia is direct, but the pressure over the internal ring should block distention of the hernia into the inguinal canal. A hernia that fills the scrotum is most likely an indirect hernia. The peritoneal contents may become incarcerated if there is swelling of the internal or external ring.

An asymptomatic hernia may be manifested as a mass that is found incidentally on physical examination of the abdomen or groin. If a hernia is easily reducible, no specific intervention is required in the ED, but give patients instructions for appropriate outpatient surgical follow-up for potential elective repair. This is particularly important for inguinal hernias because elective repair is associated with much less morbidity than emergency repair for strangulation.4,19,20

A child with an inguinal hernia may have a reducible inguinal or scrotal mass that occurs with straining or crying. Such a child may be brought to the ED because of vomiting, poor eating, lethargy, or irritability. Always consider incarcerated or strangulated hernias in the differential diagnosis of vague complaints such as these.

Radiologic Imaging

When findings on physical examination are equivocal and the emergency clinician suspects an occult hernia, several options are available for diagnostic imaging.³¹ Magnetic resonance imaging has a high positive predictive value for patients with clinically uncertain herniations,³² and computed tomography can also be helpful for the diagnosis of hernias and any associated complications (e.g., bowel obstruction or perforation)³³ (Figs. 44-6 and 44-7). Ultrasound examination has been shown to have good sensitivity and specificity for the diagnosis of groin hernias³⁴ and may decrease the rate of emergency surgery by improving the ability to reduce hernias.³⁵ Ultrasound may also have good specificity and a high positive predictive value for diagnosing postoperative incisional hernias.³¹

Figure 44-6 Incarcerated spigelian hernia identified on abdominal computed tomography. A, Dilated loops of small bowel with air-fluid levels (AFL) are noted in the abdomen. Loops of both small bowel (SB) and large bowel (LB) are seen outside the peritoneal cavity in a lateral position, which is diagnostic of a spigelian hernia. B, A cut lower in the abdomen shows the site of the hernia. The efferent loop of small bowel is of normal caliber; however, the afferent loop is decompressed, thus suggesting a transition point within the hernia. Operative repair was required.

Figure 44-7 Strangulated hernia in a 56-year-old man. An axial contrast-enhanced, reformatted computed tomography image of the abdomen shows a strangulated left inguinal hernia with a C-shaped configuration (arrows). Note the bowel wall thickening, severe fat stranding, mesenteric engorgement, and extraluminal fluid confined to the hernia sac, findings that suggest strangulation. (Reprinted with permission from Aguirre DA, Santosa AC, Casola G, et al. Abdominal wall hernias: imaging features, complications, and diagnostic pitfalls at multidetector row CT. Radiographics. 2005;25:1501-1520.)

Diagnosis of Incarcerated Versus Strangulated Hernias

When the patient or emergency care provider cannot manually reduce the contents of the hernia back into the abdominal cavity, the hernia is described as incarcerated. Although hernias are a leading cause of bowel obstruction, patients with incarcerated hernias do not necessarily have associated bowel obstruction. Incarceration is more common with femoral hernias, small indirect inguinal hernias, and abdominal wall hernias. Incarceration can be caused by the presence of a small fascial defect, by constriction of the defect by outside musculature, or by swelling of the hernia contents.

In contrast, a strangulated hernia is a hernia in which the vascular supply to the herniated bowel is compromised, thus leading to ischemia. Strangulated hernias will most commonly also be incarcerated, but this is not a universal finding. Ischemic injury of the bowel is suggested by a red, purple, or bluish discoloration of the skin over the hernia, significant abdominal tenderness with peritoneal signs, and radiographic findings of extraluminal air.²⁵ Patients with strangulated hernias may exhibit bowel obstruction, peritonitis, viscus perforation, intraabdominal abscess, or septic shock. Associated symptoms may include nausea, vomiting, fever, or abdominal distention.

In rare instances a strangulated or incarcerated hernia may inadvertently be reduced en masse to a preperitoneal location (Fig. 44-8), thus making the hernia sac and contents no longer palpable.^36–38 In this case the hernia has not been reduced into the peritoneal cavity and the incarceration and ischemia have not been relieved. Because the clinician believes that the hernia has been appropriately reduced, this can result in delay in the diagnosis of incarcerated or ischemic bowel. Fortunately, this occurs in less than 1% of hernias.³⁹ One case report described a 3-month-old patient whose gangrenous intestines were completely reduced into the peritoneal cavity (not the preperitoneal fat), thereby leading to delayed diagnosis and significant morbidity.⁴⁰ Persistent pain after reduction of a hernia, especially more than at the orifice of the fascial defect, should alert the physician to the possibility of either properitoneal reduction or reduction of ischemic bowel.

Figure 44-8 En masse reduction. A, When a hernia forms, it projects from the fascia into subcutaneous fat. The object of reduction is to replace the hernia into the peritoneal cavity. B, If the hernia sac is partially reduced into the subcutaneous fat of an obese patient, it may appear reduced and not be palpable because of the patient’s body habitus. However, the hernia is still susceptible to incarceration or ischemia because it has not been returned to the peritoneal sac.

Differential Diagnosis

The differential diagnosis for a groin mass is large. Box 44-1 lists a number of disease processes that may masquerade as hernias. For example, testicular torsion can be mistaken for a hernia, especially if there is an associated reactive hydrocele. The clinician must examine the testicle for tenderness, swelling, lie, and cremasteric reflex. If there is concern for testicular torsion, urology should be notified immediately while diagnostic studies are undertaken simultaneously. A hydrocele can also be confused with a hernia because both can occupy the same anatomic space (Fig. 44-9). A hydrocele may transilluminate, whereas a hernia generally does not. Differentiation can be difficult and may require ultrasound to define the contents of the scrotum.

Figure 44-9 Hydrocele versus hernia. A, Normal anatomy. B, Noncommunicating hydrocele (which may transilluminate) that may be confused with a hernia. C, Indirect hernia that can be palpated from the inguinal ring to the testicle.

Reduction

Indications and Contraindications

The indications for reducing a hernia are the presence of a hernia and the absence of strangulation. Because many patients require sedation for successful reduction, it may be helpful to have a surgeon available while reduction is attempted and the patient is under sedation in the ED. This may be facilitated by discussing the treatment plan with the consultant before sedating the patient and attempting reduction. If reduction proves to be difficult, do not undertake repetitive attempts at reducing the hernia because this may increase the swelling and limit the chance of nonoperative reduction by the surgical consultant. An important prognostic factor for patients requiring surgical repair is the amount of time between the onset of symptoms and repair of an incarcerated hernia.⁷

In addition to incarceration despite attempted reduction, several other clinical situations may benefit from surgical consultation. Reduction of a strangulated hernia in the ED is contraindicated and operative management will be required. Surgical consultation in the ED is indicated for bowel obstruction associated with a hernia, undescended testicles, ovaries within the hernia contents, or traumatic hernias.

Procedure

The first step in successful hernia reduction is to position the patient properly because increases in intraabdominal pressure will work against efforts to reduce a hernia. Place the patient in a position so that gravity can work to pull the contents of the hernia sac back into the peritoneal cavity. Ensure patient comfort to decrease voluntary or involuntary muscle contraction and guarding, which subsequently increases intraabdominal pressure. For ventral abdominal hernias, place the patient in the supine position. The Trendelenburg position (supine with the head 20 degrees downward) may facilitate reduction of inguinal hernias. Many of these hernias reduce spontaneously if the patient is left comfortably in this position for 10 to 20 minutes. In children, spontaneous reduction has been reported in up to 80% of inguinal hernias over a 2-hour period without manipulation.

A cool compress or ice pack may help reduce the swelling and facilitate reduction of the hernia. Before attempting reduction, consider sedation and analgesia because this will help the patient relax and minimize the pain of the procedure. Options for procedural sedation include etomidate, propofol, midazolam, and fentanyl. If manual reduction is necessary, approach slowly with soft, ongoing dialogue and warm hands. This method encourages patient relaxation and minimizes muscular contractions because of pain, cold, or other physical discomfort.

Before beginning hernia reduction, identify the components of the hernia that will be manipulated during the procedure. A hernia consists of a defect in the existing wall of tissue (muscle and fascia) that makes up the neck of the hernia sac. If the neck is small, the hernia will be more difficult to reduce, and a higher incidence of incarceration and strangulation will result. When attempting to reduce the hernia, take care to not allow the contents of the hernia sac to override the edge of the hernia orifice because this will cause “ballooning” of the contents of the hernia sack around the hernia neck. Attempt to find the edge of the hernia defect and position your hand or fingers opposite the reducing hand. This will help reduce ballooning and stabilize the edge of the fascial defect.

Begin the reduction procedure by gently guiding the proximal contents of the hernia sac back through the neck of the hernia first. In other words, reduce the hernia in the opposite order from which the contents protruded. Guiding the distal end of the contents or the hernia sac itself through the fascial defect first may cause the proximal contents to be displaced around the opening (ballooning) and prevent reduction. Apply gentle, steady pressure on the tissue at the neck of the hernia to overcome this problem and then gradually reduce the hernia (Figs. 44-10 and 44-11). Failure to perform this important procedure is a common error that precludes reduction.

Figure 44-10 A, This very large hernia is challenging to reduce. B, Merely pushing on the distal end of the mass, as shown here, will not be successful. C, Instead, try to first reduce the contents that are more proximal by stabilizing the neck and first replacing the portion of bowel closest to the fascial defect.

Figure 44-11 Hernia reduction (see Fig. 44-10).

When attempting to reduce inguinal hernias in children, place the patient supine in about a 20-degree Trendelenburg position, which may allow spontaneous reduction. Another option is to place the patient in the “unilateral frog-leg” position ⁴¹ (Fig. 44-12). Stabilize the patient by grasping the anterior superior iliac spines to prevent lateral movement of the pelvis. Abduct the ipsilateral leg, externally rotate and flex the hip, and flex the knee to obtain the classic frog-leg position. The purpose of this position is to allow the greatest reapproximation of both the internal and external rings. After achieving this position, use the fingers of one hand to prevent the hernia contents from overriding the external ring while using the other hand to provide steady but gentle pressure on the contents of the hernia sac. Repeated forceful attempts are not recommended.