Continuing Education Activity

Hernias are abnormal bulges or openings in the fascia of the abdominal wall. These defects can be present in any area of the abdominal wall fascia where there is an anatomic weakening present. Hernias are commonly located on the anterior abdominal wall (umbilical) and groin regions (inguinal, femoral). Hernias are classified as reducible when the hernia contents can be placed intra-abdominally through the layers of the abdominal wall. If the contents of the hernia are not able to be reduced, the hernia is considered incarcerated. A strangulated hernia occurs when the hernia contents are ischemic due to a compromised blood supply. This activity describes the evaluation and treatment of strangulated hernias and highlights the interprofessional team's role in managing patients with this condition.

Objectives:

• Identify the etiology among the different types of hernias that may become strangulated.
• Describe the appropriate evaluation of hernias including strangulated hernias.
• Summarize treatment options available for strangulated hernias.
• Review some interprofessional team strategies for improving care coordination and communication to advance the management of strangulated hernias.

Introduction

Hernias are abnormal bulges or openings in the fascia of the abdominal wall. These defects can be present in any area of the abdominal wall fascia where there is an anatomic weakening present. Hernias are commonly located on the anterior abdominal wall (umbilical) and groin regions (inguinal, femoral). Hernias are classified as reducible when the contents within the hernia can be placed intra-abdominally through the layers of the abdominal wall. If the contents of the hernia are not able to be reduced, the hernia is considered incarcerated. A strangulated hernia occurs when the hernia contents are ischemic due to a compromised blood supply. This phenomenon occurs most commonly when there is a small opening in the musculature and a significant quantity of contents within the hernia itself. Hernias can also form intra-abdominally by twisting of the mesentery or from a lead point such as adhesions. These internal hernias can also lead to strangulated bowel, which is a surgical emergency.

Etiology

There are several causes of hernias. A hernia can be caused by congenital predispositions or acquired from the weakening of the abdominal wall secondary to an incision or trauma. Umbilical and inguinal hernias are often present at birth and can enlarge over time. Incisional hernias can form from an iatrogenic weakness of the abdominal wall from previous surgeries. These can develop at any incision, including trocar sites over 5 mm from laparoscopic surgery.[1] Patient factors can influence hernia formation. Patients with collagen vascular disease and connective tissue disorders (Marfan syndrome, Ehlers Danlos) have weak tissue strength and are at increased risk for hernia formation.[2] Hernias form in patients with increased abdominal pressure, including pregnancy, straining due to constipation, chronic obstructive pulmonary disease (COPD), or chronic cough.[3] It is controversial whether people who engage in heavy lifting regularly are at increased risk of hernia formation.[4][5]

Epidemiology

Hernias are common, and it is estimated that 5% of individuals will develop an abdominal wall hernia over their lifetime. Inguinal hernias are approximately seven times more prevalent in men than women. The most common type of groin hernia in men and women is an indirect inguinal hernia.[6] Although inguinal hernias are also most common in women, femoral and umbilical hernias occur more frequently in women than men. Groin hernias occur more commonly on the right side due to the embryologic delayed or failed closure of the processus vaginalis. Femoral hernias are also more common on the right side, which may be due to a lack of sigmoid colon covering the femoral canal. Hernias increase with age and strain on the abdominal wall over time. The risk of a hernia becoming incarcerated or strangulated is estimated between 1% to 3% over a person’s lifetime.[7] Femoral hernias can become incarcerated up to 30% of the time and should always be repaired surgically when found.[8]

Pathophysiology

The anatomy of the abdominal wall is of great importance when evaluating a patient for a hernia. The abdominal wall is formed by several layers of adipose tissue, fascia, and musculature. In the midline, the rectus abdominis muscle runs longitudinally from the pubic symphysis to the sternum and ribs. Laterally there are three layers of muscle that run in oblique patterns to prevent abdominal wall herniation. The external oblique, internal oblique, and transversus abdominus coalesce to form fascial sheaths surrounding the rectus abdominis.

There are weak points in the abdominal wall where the muscle and fascial layers are attenuated. In the inguinal canal, several anatomic boundaries will help delineate which type of hernia is present. Hasselbach’s triangle is bounded by the rectus abdominis medially, the inguinal canal inferior laterally, and the inferior epigastric vessels superiorly. Direct inguinal hernias occur within this triangle. Hernias that occur lateral to the inferior epigastric vessels and along the inguinal ring are classified as indirect inguinal hernias. There is a weakness here due to the thinning of the external and internal oblique to form an aponeurosis. This weakness leaves the transversalis fascia and peritoneum without additional muscular support. Femoral hernias occur inferior to the inguinal canal within the femoral space and medial to the femoral vessels.[9]

History and Physical

A history of trauma, heavy lifting, or chronic bulge may be elicited from the patient. The patient will usually describe a bulge and pain, which is worse when lifting or straining. When strangulation exists, the patient may present with bowel obstruction symptoms, including nausea, vomiting, and obstipation. If bowel ischemia is present, the patient will have severe pain and may present with sepsis (hypotension, tachycardia). Before palpating the abdominal wall, it is important to inspect the skin overlying the hernia visually. Any appearance of erythematous or dusky skin is a concern for a possible strangulated hernia. An emergent surgical consult should be obtained if skin changes are noted before attempting to reduce the hernia. When evaluating a patient for a hernia, it is essential to ask the patient to increase abdominal pressure via a Valsalva maneuver.

The patient should be evaluated in both the sitting and standing position. Palpate the area of the abdominal wall to evaluate for a hernia during Valsalva, and a bulge or weakening of the abdominal musculature should be appreciated. When evaluating for inguinal hernias in males while standing, invaginate the scrotum and place a finger within the external inguinal ring to palpated for a bulge. There should be a push against your finger when the patient is performing a Valsalva maneuver. Large hernias in the groin area may appear as a mass in the femoral area near the vessels or a scrotal mass. Hernias that are acutely incarcerated will appear erythematous, indurated, swollen, and painful to palpation. When there is a bowel within the hernia defect, you may feel peristalsis of fluid in the hernia sac. If bowel strangulation is present, the patient may have focal or generalized peritonitis on examination.

Evaluation

The majority of hernias can be diagnosed with physical examination alone. In patients who have an exam that causes concern for a strangulated hernia, it is important to rule out bowel ischemia. Complete blood count and basic metabolic panel should be checked for leukocytosis and metabolic abnormalities. A lactate level can be helpful, although, with acute strangulated small bowel, this level may be falsely normal up to 8 hours while the blood supply is compromised.[10] Ultrasound is the best initial test in determining whether a hernia is present, especially if there are concerns for testicular etiology of the patient’s pain. A CT abdomen and pelvis can help delineate anatomy and determine if the bowel is strangulated within the hernia. MRI is a more sensitive test than CT scan in diagnosing occult hernias and can determine if there are associated musculoskeletal injuries noted, but it is not as useful in the acute setting. Another useful technique to diagnose occult hernias is by diagnostic laparoscopy, although this is not usually necessary.[11][12][13]

Treatment / Management

Patients with non-incarcerated hernias may be offered elective surgical repair based on their symptomatology. For patients with moderate to severe symptoms who are healthy enough to undergo surgery, surgical repair is indicated.[14] For an older patient with multiple comorbidities and a relatively asymptomatic hernia, a watchful waiting approach may be warranted due to the low risk of strangulation.[15] For an acutely incarcerated hernia without bowel present, the manual reduction can be attempted. Sedation may be necessary if this area is particularly painful for the patient. The patient should be supine, and Trendelenburg may help reduce incarcerated groin hernias. Gentle pressure on the hernia itself from all sides will help the hernia reduce intra-abdominally. Ice helps reduce acute inflammation of the hernia sac. An acutely incarcerated hernia with concern for strangulation is an indication for emergent surgery. Femoral hernias have a higher risk for incarceration and should be repaired soon after diagnosis to avoid future complications. When a strangulated hernia is suspected, an emergent surgical consultation should be obtained. If bowel obstruction is present, consider placing a nasogastric tube for decompression and ensure the patient has appropriate fluid resuscitation. If there is suspicion for bowel necrosis or perforation, broad-spectrum antibiotics should be started.[16]

Surgical repair of the strangulated hernia will depend on the operative skill and choice of the surgeon. Studies have shown success with a laparoscopic or robotic technique to evaluate strangulated bowel. Depending on the surgeon's skill and experience, bowel resection may also be performed using a minimally invasive technique. For surgeons not experienced in laparoscopic approaches, open approaches are equally successful.[17][18][19] The bowel must be adequately visualized and evaluated to determine viability before closing the defect. Studies have shown safe placement of synthetic mesh in the acute setting, but most surgeons would avoid placing synthetic mesh to reduce the risk of seeding the mesh with bacteria, especially when a bowel resection was performed. For incarcerated hernias without bowel strangulation, synthetic mesh placement has been proven to be safe and best practice to prevent recurrent hernia formation.[20][21][22] Closing the hernia defect primarily with a tissue technique or placement of a non-synthetic (biologic acellular dermal matrix) are additional options well described in the acute setting.[23]

Differential Diagnosis

Groin mass: lymphadenopathy, abscess, undescended testicle, vascular aneurysm, lipoma

Scrotal mass: hydrocele, testicular tumor, varicocele, testicular torsion

Groin pain: musculoskeletal injury, athletica pubalgia (sports hernia), epididymitis

• Abscess
• Athletica pubalgia
• Epididymitis
• Hydrocele
• Lipoma
• Lymphadenopathy
• Musculoskeletal injury
• Testicular torsion
• Testicular tumor
• Varicocele
• Vascular aneurysm
• Undescended testicle

Prognosis

Overall mortality and prognosis are influenced by whether the surgery was emergent or elective. For elective surgical repair of a groin hernia, the risk of mortality is low at 0.1%. Mortality is increased to up to 3% with emergency surgery for strangulated bowel, notably when bowel resection is performed.[24]

Complications

Complications are more common in emergent surgeries and in patients who have had previous abdominal surgeries or hernia repairs. Very large hernias can distort the normal anatomy and increase the risk of injury to intra-abdominal structures. Complications related to hernia surgery are more common in patients undergoing emergent surgery with multiple co-morbidities and increased age.[24]

• Surgical site infection
• Hematoma
• Wound dehiscence
• Chronic pain
• Anastomotic leak (when bowel resected)
• Bowel necrosis
• Testicular necrosis
• Nerve injury
• Vascular injury

Postoperative and Rehabilitation Care

Ongoing resuscitation is vital for patients who presented with a bowel obstruction. Nasogastric tube decompression should be left in place until an ileus has resolved or output has slowed significantly. Once bowel function has returned, the patient may be discharged home. Lifting precautions should be in place for 6 to 8 weeks.

Consultations

A surgeon should be consulted emergently when there is a concern for strangulated bowel within a hernia.

Deterrence and Patient Education

The most common cause of small bowel obstruction is an incarcerated hernia. A patient who presents with bowel obstruction should be evaluated for hernias. Any skin changes noted with a concomitant hernia should raise suspicion for a strangulated hernia. An emergent surgical consultation should be obtained before attempting to reduce a strangulated hernia.

Enhancing Healthcare Team Outcomes

It is important for direct communication between the emergency department and the surgical team when a strangulated hernia is suspected. Delay in diagnosis and treatment can significantly affect morbidity and mortality.[22][25] [Level 1]

Once the determination of a strangulated hernia is made, an interprofessional team approach is necessary to optimize treatment and recovery. This team will include surgeons, primary care clinicians (including NPs and PAs), and pharmacists, all coordinating activities across interprofessional lines to bring about the best patient outcomes. [Level 5]