A hernia is a protrusion of any viscus from its proper cavity. A hernia can lead to an incarcerated and often obstructed bowel or a strangulated bowel with a compromised blood supply. Over 1 million abdominal wall hernia repairs are performed each year in the United States, with inguinal hernia repairs constituting nearly 770,000 of these cases; approximately 90% of all inguinal hernia repairs are performed on males.[1, 2, 3]
Essential update: Reduced surgical site infections with laparoscopic repair of primary ventral hernias
In a retrospective cohort study of 79 patients who underwent laparoscopic repair of primary ventral hernias and 79 who underwent open hernia repair, patients with a laparoscopic ventral hernia repair were significantly less likely to develop a surgical site infection (7.6% vs 34.1%). However, patients who underwent laparoscopic repair were more likely to develop a postoperative ileus (10.1% vs 1.3%), to have a persistent bulge at the operative site (21.5% vs 1.3%), and to have a longer hospital stay.[4, 5, 6]
Signs and symptoms
Hernias may be detected on routine physical examination, or patients with hernias may present because of a complication associated with the hernia.
Asymptomatic hernia
Swelling or fullness at the hernia site
Aching sensation (radiates into the area of the hernia)
No true pain or tenderness upon examination
Enlarges with increasing intra-abdominal pressure and/or standing
Incarcerated hernia
Painful enlargement of a previous hernia or defect
Cannot be manipulated (either spontaneously or manually) through the fascial defect
Nausea, vomiting, and symptoms of bowel obstruction (possible)
Strangulated hernia
Patients have symptoms of an incarcerated hernia
Systemic toxicity secondary to ischemic bowel is possible
Strangulation is probable if pain and tenderness of an incarcerated hernia persist after reduction
Suspect an alternative diagnosis in patients who have a substantial amount of pain without evidence of incarceration or strangulation
Site-specific findings
With femoral hernia, medial thigh pain and groin pain are possible. Patients with obturator hernia may not have local swelling, because this hernia is hidden within deeper structures; instead, the patient may complain of abdominal pain or medial thigh pain, weight loss, or recurrent episodes of bowel or partial bowel obstruction. Pressure on the obturator nerve causes pain in the medial thigh that is relieved by thigh flexion. This same pain may be exacerbated by extension or external rotation of the hip (Howship-Romberg sign)
Incisional hernias at sites of prior abdominal surgery are usually asymptomatic. Patients present with a bulge at the site. The bulge may become larger upon standing or with increasing intra-abdominal pressure.
Physical examination
In general, the physical examination should be performed with the patient in both the supine and the standing positions, with and without the Valsalva maneuver. The examiner should attempt to identify the hernia sac as well as the fascial defect through which it is protruding. This allows proper direction of pressure for reduction of hernia contents. The examiner should also identify evidence of obstruction and strangulation.
When attempting to identify a hernia, look for a swelling or mass in the area of the fascial defect, as follows:
For inguinal hernias, place a fingertip into the scrotal sac and advance up into the inguinal canal
If the hernia is elsewhere on the abdomen, attempt to define the borders of the fascial defect
If the hernia comes from superolateral to inferomedial and strikes the distal tip of the finger, it most likely is an indirect hernia
If the hernia strikes the pad of the finger from deep to superficial, it is more consistent with a direct hernia
A bulge felt below the inguinal ligament is consistent with a femoral hernia
Strangulated hernias are differentiated from incarcerated hernias by the following:
Pain out of proportion to examination findings
Fever or toxic appearance
Pain that persists after reduction of hernia
See Clinical Presentation for more detail.
Diagnosis
Laboratory studies include the following:
CBC – Results are nonspecific; leukocytosis with left shift may occur with strangulation
Electrolytes, BUN, creatinine levels – Assess the hydration status of the patient with nausea and vomiting; rarely needed for patients with hernia except as part of a preoperative workup
Urinalysis – Assists with narrowing the differential diagnosis of genitourinary causes of groin pain in the setting of associated hernias
Lactate level – Elevated levels may reflect hypoperfusion; a normal level does not necessarily eliminate strangulation
Imaging studies
Imaging studies are not required in the normal workup of a hernia.[7, 8] However, ultrasonography can be used in differentiating masses in the groin or abdominal wall or in differentiating testicular sources of swelling. If an incarcerated or strangulated hernia is suspected, the following imaging studies can be performed:
Upright chest radiograph to exclude free air (extremely rare)
Flat and upright abdominal films to diagnose a small bowel obstruction (neither sensitive nor specific) or to identify areas of bowel outside the abdominal cavity
CT scanning or ultrasonography may be necessary if a good examination cannot be obtained, because of the patient’s body habitus, or in order to diagnose a spigelian or obturator hernia. Spigelian hernia is a rare form of abdominal wall hernia that occurs through a defect in the spigelian fascia, which is defined by the lateral edge of the rectus muscle at the semilunar line (costal arch to the pubic tubercle).
See Workup for more detail.
Management
Spontaneous reduction requires adequate sedation/analgesia, Trendelenburg positioning, and padded cold packs applied to the hernia for 20-30 minutes. This technique can be attempted prior to manual reduction attempts. Manual hernia reduction is performed as follows[9, 1, 10] :
Provide adequate sedation and analgesia to prevent straining or pain; the patient should be relaxed enough to not increase intra-abdominal pressure or to tighten the involved musculature
Place the patient supine with a pillow under his or her knees
Place the patient in a Trendelenburg position of approximately 15-20° for inguinal hernias
Apply a padded cold pack to the area to reduce swelling and blood flow while establishing appropriate analgesia
Place the ipsilateral leg in an externally rotated and flexed position resembling a unilateral frog leg position
Place 2 fingers at the edge of the hernial ring to prevent the hernial sac from riding over the ring during reduction attempts
Apply firm, steady pressure to the side of the hernia contents close to the hernia opening, guiding it back through the defect; applying pressure at the apex, or first point, that is felt may cause the herniated bowel to "mushroom" out over the hernia opening instead of advancing through it
Consult with a surgeon if reduction is unsuccessful after 1 or 2 attempts; do not use repeated forceful attempts
All incarcerated or strangulated hernias demand admission and immediate surgical evaluation. For strangulated hernias, start broad-spectrum antibiotics. Antibiotics are administered routinely if ischemic bowel is suspected.
Surgical consultation
Consult a surgeon for the following reasons[11, 12, 13] :
Inability to reduce the hernia
Concern for a strangulated bowel and a patient with a toxic appearance
Patients with comorbid risks for sedation should have a surgeon present for the initial reduction attempt
A hernia, as defined in 1804 by Astley Cooper, is a protrusion of any viscus from its proper cavity. The protruded parts are generally contained in a sac-like structure, formed by the membrane with which the cavity is naturally lined.[11]
Since that time, many different types of abdominal wall hernias have been identified, along with a larger number of associated eponyms. This article reviews the pathophysiology, evaluation, and treatment of most of these hernias from an emergency medicine perspective. Hernias are brought to the attention of an emergency physician either during a routine physical examination for other medical complaints or when the patient has developed a complication associated with the hernia.
An indirect inguinal hernia follows the tract through the inguinal canal. This results from a persistent process vaginalis. The inguinal canal begins in the intra-abdominal cavity at the internal inguinal ring, located approximately midway between the pubic symphysis and the anterior iliac spine. The canal courses down along the inguinal ligament to the external ring, located medial to the inferior epigastric arteries, subcutaneously and slightly above the pubic tubercle. Contents of this hernia then follow the tract of the testicle down into the scrotal sac.[9, 12, 7]
Direct hernia
A direct inguinal hernia usually occurs due to a defect or weakness in the transversalis fascia area of the Hesselbach triangle. The triangle is defined inferiorly by the inguinal ligament, laterally by the inferior epigastric arteries, and medially by the conjoined tendon.[14]
Femoral hernia
The femoral hernia follows the tract below the inguinal ligament through the femoral canal. The canal lies medial to the femoral vein and lateral to the lacunar (Gimbernat) ligament. Because femoral hernias protrude through such a small defined space, they frequently become incarcerated or strangulated.[8]
Umbilical hernia
The umbilical hernia occurs through the umbilical fibromuscular ring, which usually obliterates by 2 years of age. They are congenital in origin and are repaired if they persist in children older than age 2-4 years.[9, 14]
Richter hernia
The Richter hernia occurs when only the antimesenteric border of the bowel herniates through the fascial defect. The Richter hernia involves only a portion of the circumference of the bowel. As such, the bowel may not be obstructed, even if the hernia is incarcerated or strangulated, and the patient may not present with vomiting. The Richter hernia can occur with any of the various abdominal hernias and is particularly dangerous, as a portion of strangulated bowel may be reduced unknowingly into the abdominal cavity, leading to perforation and peritonitis.[8]
Incisional hernia
This iatrogenic hernia occurs in 2-10% of all abdominal operations secondary to breakdown of the fascial closure of prior surgery. Even after repair, recurrence rates approach 20-45%.
Spigelian hernia
This rare form of abdominal wall hernia occurs through a defect in the spigelian fascia, which is defined by the lateral edge of the rectus muscle at the semilunar line (costal arch to the pubic tubercle) The two subtypes are interstitial and subcutaneous, which are best defined using CT and assist with optimizing the surgical approach when indicated.[15, 16, 17]
Obturator hernia
This hernia passes through the obturator foramen, following the path of the obturator nerves and muscles. Obturator hernias occur with a female-to-male ratio of 6:1, because of a gender-specific larger canal diameter and predominately in the elderly. Because of its anatomic position, this hernia presents more commonly as a bowel obstruction than as a protrusion of bowel contents.[11, 18]
Types of Hernia - Condition
Reducible hernia: This term refers to the ability to return the contents of the hernia into the abdominal cavity, either spontaneously or manually.
Incarcerated hernia: An incarcerated hernia is no longer reducible. The vascular supply of the bowel is not compromised; however, bowel obstruction is common.
Strangulated hernia: A strangulated hernia occurs when the vascular supply of the bowel is compromised secondary to incarceration of hernia contents.
Over 1 million abdominal wall hernia repairs are performed each year, with inguinal hernia repairs constituting nearly 770,000 of these cases.[1, 2, 3]
Approximately 25% of males and 2% of females have inguinal hernias in their lifetimes representing the most common hernia in males and females.[3, 19]
Approximately 75% of all hernias occur in the groin; two thirds of these hernias are indirect and one third direct.[9]
Indirect inguinal hernias are the most common hernias in both men and women; a right-sided predominance exists.
Incisional and ventral hernias account for 10% of all hernias.[7]
Only 3% of hernias are femoral hernias.
The incidence of inguinal hernias in children ranges up to 4.5%, while umbilical hernias occur in approximately 1 out of every 6 children.[2, 9]
The incidence of incarcerated or strangulated hernias in pediatric patients is 10-20%; 50% of these occur in infants younger than 6 months.[2]
International
Data from developing countries is limited, therefore, an accurate occurrence value is unavailable. Current epidemiologic assessments postulate that gender and anatomic distribution are similar.
Morbidity is secondary to missing the diagnosis of the hernia or complications associated with management of the disease.
A hernia can lead to an incarcerated and often obstructed bowel.
The hernia also can lead to strangulated bowel with a compromised blood supply. Reduced strangulated bowel leads to persistent ischemia/necrosis with no clinical improvement. Surgical intervention is required to prevent further complications such as perforation and sepsis.
Ensuing surgery to repair the hernia or its complications may leave the patient at risk for infection, future hernias, or intra-abdominal adhesions.
Race
Umbilical hernias occur 8 times more frequently in black infants than in white infants.[19]
Sex
Approximately 90% of all inguinal hernia repairs are performed on males.[3]
Reduction of hernias in females may be complicated by inclusion of the ovary in the hernia.
Femoral hernias (although rare) occur almost exclusively in women because of the differences in the pelvic anatomy.
The female-to-male ratio of obturator hernias is 6:1.[19]
Age
Indirect hernias usually present during the first year of life, but they may not appear until middle or old age.
Indirect hernias occur more frequently in premature infants compared to term infants. Indirect hernias develop in 13% of infants born before 32 weeks' gestation.[2]
Direct hernias occur in older patients as a result of relaxation of abdominal wall musculature and thinning of the fascia.
Umbilical hernias usually occur in infants and reach their maximal size by the first month of life. Most hernias of this type close spontaneously by the first year of life, with only a 2-10% incidence in children older than 1 year.[20]
Obturator hernias occur predominately in the elderly.
Patients with hernias present to the emergency department (ED) secondary to a complication associated with the hernia. Hernias also may be detected in the ED on routine physical examination. However, in relation to the chief complaint, the following clinical issues must be considered:
Asymptomatic hernia
Presents as a swelling or fullness at the hernia site
Aching sensation (radiates into the area of the hernia)
No true pain or tenderness upon examination
Enlarges with increasing intra-abdominal pressure and/or standing
Incarcerated hernia
Painful enlargement of a previous hernia or defect
Cannot be manipulated (either spontaneously or manually) through the fascial defect
Nausea, vomiting, and symptoms of bowel obstruction (possible)
Strangulated hernia
Symptoms of an incarcerated hernia present combined with a toxic appearance
Systemic toxicity secondary to ischemic bowel is possible
Strangulation is probable if pain and tenderness of an incarcerated hernia persist after reduction
Suspect an alternative diagnosis in patients who have a substantial amount of pain without evidence of incarceration or strangulation
Further anatomic considerations must be assessed in relation to the above clinical findings. The location of the underlying hernia may provide a unique constellation of symptoms with or without specific anatomic findings.
Femoral hernia
Medial thigh pain as well as groin pain are possible because of the position of this hernia
Obturator hernia
Because this hernia is hidden within deeper structures, it may not present as a swelling
The patient may complain of abdominal pain or medial thigh pain, weight loss, or recurrent episodes of bowel or partial bowel obstruction
Pressure on the obturator nerve causes pain in the medial thigh that is relieved by thigh flexion. This same pain may be exacerbated by extension or external rotation of the hip (Howship-Romberg sign)
Incisional hernia
As these are usually asymptomatic, patients present with a bulge at the site of a previous incision
Lesion may become larger upon standing or with increasing intra-abdominal pressure
In general, the physical examination should be performed with the patient in both the supine and standing positions, with and without the Valsalva maneuver. The examiner should attempt to identify the hernia sac as well as the fascial defect through which it is protruding. This allows proper direction of pressure for reduction of hernia contents. The examiner should also identify evidence of obstruction and strangulation.
When attempting to identify a hernia, look for a swelling or mass in the area of the fascial defect.
Place a fingertip into the scrotal sac and advance up into the inguinal canal. If the hernia is elsewhere on the abdomen, attempt to define the borders of the fascial defect.
If the hernia comes from superolateral to inferomedial and strikes the distal tip of the finger, it most likely is an indirect hernia.
If the hernia strikes the pad of the finger from deep to superficial, it is more consistent with a direct hernia.
A bulge felt below the inguinal ligament is consistent with a femoral hernia.
Strangulated hernias are differentiated from incarcerated hernias by the following:
Imaging studies are not required in the normal workup of a hernia.[7, 8]
Ultrasonography can be used in differentiating masses in the groin or abdominal wall or in differentiating testicular sources of swelling.
If an incarcerated or strangulated hernia is suspected, the following imaging studies can be performed:
Upright chest radiograph to exclude free air (extremely rare)
Flat and upright abdominal films to diagnose a small bowel obstruction (neither sensitive or specific) or to identify areas of bowel outside the abdominal cavity
CT scanning or ultrasonography may be necessary in the following cases:
To diagnose a spigelian or obturator hernia
Inability to obtain a good examination because of body habitus
Provide adequate sedation and analgesia to prevent straining or pain. The patient should be relaxed enough to not increase intra-abdominal pressure or to tighten the involved musculature.
Place the patient supine with a pillow under his or her knees.
Place the patient in a Trendelenburg position of approximately 15-20° for inguinal hernias.
Apply a padded cold pack to the area to reduce swelling and blood flow while establishing appropriate analgesia.
Place the ipsilateral leg in an externally rotated and flexed position resembling a unilateral frog leg position.
Place 2 fingers at the edge of the hernial ring to prevent the hernial sac from riding over the ring during reduction attempts.
Apply firm, steady pressure to the side of the hernia contents close to the hernia opening, guiding it back through the defect.
Applying pressure at the apex, or first point, that is felt may cause the herniated bowel to "mushroom" out over the hernia opening instead of advancing through it.
Consult with a surgeon if reduction is unsuccessful after 1 or 2 attempts; do not use repeated forceful attempts.
The spontaneous reduction technique requires adequate sedation/analgesia, Trendelenburg positioning, and padded cold packs applied to the hernia for 20-30 minutes. This can be attempted prior to manual reduction attempts.
Clinical Context:
Multiple regimens that cover for bowel perforation and/or ischemic bowel can be used. Cover for both aerobic and anaerobic gram-negative bacteria.
Follow-up visits with the general surgeon should be scheduled within the next 1-2 weeks for those patients with easily reducible hernias or with hernias found upon physical examination.
Discharge patients with umbilical hernias with close follow-up care if the defect is less than 2 cm in diameter and the hernia is not incarcerated or strangulated.
Educate patients to avoid those activities that increase intra-abdominal pressure.
Educate patients to return for inability to reduce hernia, increased pain, fever, and vomiting.
Counsel the patient on avoidance of activities that increase intra-abdominal pressure, such as straining at defecation or lifting heavy objects. This may require work or school-related activity restrictions and should be clearly delineated.
Bret A Nicks, MD, MHA, Assistant Dean of Global Health, Assistant Professor, Medical Director, ED Clinical Operations, Department of Emergency Medicine, Wake Forest University School of Medicine
Disclosure: Nothing to disclose.
Coauthor(s)
Kim Askew, MD, Assistant Professor, Director of Undergraduate Medical Education, Department of Emergency Medicine, Wake Forest University School of Medicine
Disclosure: Nothing to disclose.
Specialty Editors
Richard Lavely, MD, JD, MS, MPH, Lecturer in Health Policy and Administration, Department of Public Health, Yale University School of Medicine
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Medscape Salary Employment
Eugene Hardin, MD, FAAEM, FACEP, Former Chair and Associate Professor, Department of Emergency Medicine, Charles Drew University of Medicine and Science; Former Chair, Department of Emergency Medicine, Martin Luther King Jr/Drew Medical Center
Disclosure: Nothing to disclose.
John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
Disclosure: Nothing to disclose.
Chief Editor
Steven C Dronen, MD, FAAEM, Chair, Department of Emergency Medicine, LeConte Medical Center
Disclosure: Nothing to disclose.
References
Manthey DE. Abdominal hernia reduction. In: Clinical Procedures in Emergency Medicine. 2003.
Henderson D. Laparoscopic Repair Better for Primary Ventral Hernias?. Available at http://www.medscape.com/viewarticle/810457. Accessed September 6, 2013.
Smith S. Inguinal hernia reduction. In: King C, Henretig FM, eds. Textbook of Pediatric Emergency Procedures. 2nd ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2008:840-847/87.
Eubanks S. Hernias. In: Sabiston DC Jr, ed. Textbook of Surgery: The Biological Basis of Modern Surgical Practice. 1997.
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