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]
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]
Hernias may be detected on routine physical examination, or patients with hernias may present because of a complication associated with the hernia.
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.
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:
Strangulated hernias are differentiated from incarcerated hernias by the following:
See Clinical Presentation for more detail.
Laboratory studies include the following:
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:
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.
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] :
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.
Consult a surgeon for the following reasons[11, 12, 13] :
See Treatment and Medication for more detail.
Anatomic locations for various hernias.
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.
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.
See Medscape's Hernia Resource Center.
See the image below.
Anatomic locations for various hernias.
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]
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.
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.
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]
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.
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%.
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]
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]
Morbidity is secondary to missing the diagnosis of the hernia or complications associated with management of the disease.
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:
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.
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.
Any condition that increases the pressure in the intra-abdominal cavity may contribute to the formation of a hernia, including the following:
Consult a surgeon for the following reasons:[11, 13, 12]
For strangulated hernias, start broad-spectrum antibiotics. Antibiotics are administered routinely if ischemic bowel is suspected.
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.
These agents are to be used if the patient has a strangulated hernia.