Indirect Inguinal Hernia

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.

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.

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

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.

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

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.