Abdominal Hernia Reduction

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Chapter 44

Abdominal Hernia Reduction

When a patient is seen in the emergency department (ED) with a suspected abdominal hernia, the emergency clinician must consider three issues: (1) Is a palpable mass truly a hernia? (2) Is the hernia easily reducible or incarcerated? (3) Is the vascular supply to the bowel strangulated? A patient with an easily reducible hernia can be discharged safely for outpatient follow-up and elective repair, whereas incarcerated and strangulated hernias are a surgical emergency. Some seemingly incarcerated hernias can be reduced by careful manipulation in the ED. Any patient with symptoms of bowel obstruction should also be evaluated for the possible presence of an abdominal hernia (Fig. 44-1).1

Hernias in the groin area have been the subject of medical diagnosis and treatment as long ago as 1550 bc. Throughout history, treatment of this condition has been the focus of ongoing discussion and debate.2–7 This chapter addresses abdominal and groin hernias, which are amenable to diagnosis and potential manual reduction in the ED. These types include ventral hernias of the abdominal wall, direct and indirect groin hernias, femoral hernias, and pantaloon hernias.

Background

A hernia is defined as protrusion of any viscus from its normal cavity through an abnormal opening. Abdominal hernias are characterized by protrusion of intraabdominal contents (usually bowel, with or without mesentery) through an abnormal defect in the abdominal wall musculature. Hernias can develop along a congenital tract that fails to close (e.g., indirect inguinal hernia) or along an area of weakness in the muscular and fascial wall layers (e.g., direct inguinal hernia or incisional hernia). This weakness may be due to aging and the accompanying loss of tissue elasticity, increased intraabdominal pressure, or trauma involving the abdominal wall itself. It is estimated that hernias develop in 5% of the male population and 2% of the female population8,9 and that 75% of them occur in the groin.10 In children and young adults, the majority of hernias are indirect inguinal hernias of congenital origin,11 whereas direct hernias are acquired and become more common as the patient ages.12

Classification

One of the first priorities for the emergency clinician is to determine whether a suspected hernia is reducible, incarcerated, or strangulated. A reducible hernia is one whose contents can be returned through the fascial defect back into the abdominal cavity without surgical intervention. Patients often have rather large reducible hernias for years and are able to reduce them themselves, but such hernias can also become strangulated or incarcerated. An incarcerated hernia is one whose contents are not reducible without surgical intervention and is often associated with swelling of the hernia sac contents. A strangulated hernia is an incarcerated hernia whose blood supply to the herniated structures is compromised. Hernias with a small neck are more likely to strangulate. A strangulated hernia is a surgical emergency because gangrene will result if blood flow is not returned.

The anatomic location of the hernia will help one determine which type is most likely to be found. A ventral hernia of the abdominal wall may be umbilical, epigastric, or spigelian, depending on its location. An incisional hernia is found along a previous surgical scar. An inguinal hernia is found within the inguinal triangle, which is formed by the inguinal ligament on the inferior side, the inferior epigastric artery on the superolateral side, and the lateral edge of the rectus abdominis muscle on the medial side. Direct and indirect inguinal hernias occur superior to the inguinal ligament, whereas a femoral hernia is located inferior to the inguinal ligament.

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

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

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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.

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

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