Hernia Reduction

A hernia is a protrusion of tissue through a defect in its encapsulating walls. This defect occurs frequently; hernia repair is the most common operation in general surgery.[1]

Hernias may be broadly divided into two main groups, depending on whether they develop in the upper abdomen or in the groin (see the image below), and each group contains multiple types.

Variations of hernia type and location.

Groin hernias include the following:

• Indirect inguinal hernia - Bounded by the inguinal (Hesselbach) triangle, an indirect inguinal hernia passes through the internal inguinal ring; it is the most common hernia type and is more commonly seen in males
• Direct inguinal hernia - This type is similarly bounded by the inguinal triangle, but it passes directly through the muscular and fascial wall of the abdomen; it carries a minimal risk of incarceration
• Femoral hernia - Originating below the inguinal ligament, a femoral hernia passes through the transversalis fascia and through the femoral canal; it presents a high risk of incarceration ^[2]

Abdominal hernias include the following:

• Umbilical hernia - This type (see the image below) is seen traversing the fibromuscular ring at the umbilicus; commonly seen in infants, it usually resolves by the age of 5 years; repair is indicated when an umbilical hernia develops in older children or adults, is larger than 2 cm, or is incarcerated ^[3]
• Epigastric hernia - This type is a midline hernia that passes through the linea alba
• Spigelian hernia - This rare type is located at the lateral edge of the rectus abdominis and passes through the semilunar line

50-year-old man presents with recurrent umbilical hernia, which is reduced in emergency department.

Before surgical repair of a hernia, manual reduction can return the tissue to its original compartment.[4] Reduction benefits the patient by mitigating associated symptoms, avoiding adverse outcomes such as strangulation, and permitting elective surgical repair, which has lower morbidity than emergency repair.[5, 6]  The most common hernias amenable to reduction are described in this article.

The presence of a nonstrangulated hernia is an indication for manual reduction.[7] Although an incarcerated hernia can be strangulated without the usual signs and symptoms of strangulation, reduction should be performed for most incarcerated hernias when clinical evidence of strangulation is not present.

Although strangulation can be missed,[8] one prospective study showed that clinicians are usually correct in deciding when to reduce an incarcerated hernia and when to defer reduction of a strangulated hernia.[9] In addition, harmful outcomes to attempted reduction are unlikely in these unrecognized strangulated hernias.

Manual reduction is contraindicated in strangulated hernias. In such cases, nasogastric suction, fluid replacement, and antibiotic therapy can be started.

If the diagnosis of strangulated hernia is missed and manual reduction is performed, necrotic bowel may be introduced into the abdomen. This could result in clinical deterioration and could necessitate urgent reduction in the operating room.[10]

For the purposes of manual reduction, hernias are best classified into the following three groups[11] :

• Easily reducible hernia
• Incarcerated hernia
• Strangulated hernia

This classification also helps direct treatment.

Easily reducible hernia

If a hernia is easily reducible, the abdominal contents can easily be returned to their original compartment. Reduction not only allows symptomatic relief for patients but also reduces the risk of future incarceration.[2]  Although reduction helps alleviate patient's symptoms, elective surgical repair is usually warranted for long-term management.

In some cases, nonoperative treatment may suffice for asymptomatic patients with easily reducible hernias. A large prospective trial suggested that in patients who are minimally symptomatic, nonoperative treatment can produce outcomes similar to those experienced by minimally symptomatic patients who undergo surgical repair.[12]

Incarcerated hernia

An incarcerated hernia cannot easily be returned to its original compartment. The overlying skin should appear to be normal, the contents should not be tense, and bowel sounds can sometimes be heard. The incarcerated tissue may be bowel, omentum, or other abdominal contents. A smaller aperture of herniation and adhesions can precipitate incarceration. An incarcerated hernia can often be reduced manually, especially with sufficient anesthesia.[9, 13]

Obstruction is a concern; a hernia is one of the three most common causes of obstruction. In addition to causing signs of obstruction, an obstructed hernia has a more tense appearance than a nonobstructed hernia, and diagnostic imaging may show bowel shadows at the site of herniation. (See the image below.)

64-year-old woman presents with vague abdominal pain of 2 days' duration. Physical examination reveals tender palpable mass in left lower quadrant. CT reveals incarcerated ventral hernia.

Even with proper sedation and technique, not every hernia can be manually reduced. In such cases, surgical reduction is more urgent to prevent strangulation.[14, 15]

Strangulated hernia

A strangulated hernia (see the image below) is a surgical emergency in which the blood supply to the herniated tissue is compromised. Strangulation stems from herniated bowel contents passing through a restrictive opening that eventually reduces venous return and leads to increased tissue edema, which further compromises circulation and stops the arterial supply.

Erythematous edematous left scrotum in 2-month-old boy with history of irritability and vomiting for 36 hours. Local signs of this magnitude preclude reduction attempts.

Such a hernia may be signaled in the early stages by severe pain and by tenderness, induration, and erythema over the herniation site. As tissue necrosis ensues, findings may include leukocytosis, decreased bowel sounds, abdominal distention, and a patient who appears to be toxic, dehydrated, and febrile. Mortality is high, and treatment should be initiated immediately.[16]

Equipment used in hernia reduction includes the following:

• Means of anesthesia or sedation
• Cold compress
• Gurney capable of Trendelenburg positioning

Anesthesia

Anesthesia is generally not required for most reductions. Procedural sedation is recommended if the patient is a young child. Procedural sedation can also be used in adults if a difficult reduction is expected or if initial attempts without sedation are unsuccessful. Epidural anesthesia has also been successfully used and might be an alternative for infants.[17] Ilioinguinal nerve blocks have been used as an adjunct for pain control for inguinal hernias.[18, 19]

Positioning

For reduction of an inguinal hernia, the patient should be placed in a 20° Trendelenburg position (see the image below). Gravity pulls the bowel contents inward from the site of herniation and facilitates reduction. A supine position is appropriate for a hernia of the upper abdomen.

40-year-old man presents with left inguinal pain, swelling, and erythema consistent with left inguinal hernia. He is placed in Trendelenburg position to aid in reduction.

Apply ice or cold compress to the hernia for several minutes to reduce swelling and allow an easier reduction (see the image below).

Ice pack is applied to patient with left inguinal hernia in Trendelenburg position.

To reduce an abdominal hernia, lay the patient supine.[4] To reduce a groin hernia, place the patient in a 20º Trendelenburg position (this position allows gravity to help retract the herniated tissue into the abdomen or pelvis). In children, a unilateral frog leg position has been shown to align the inguinal rings for better reduction.

Use sufficient early sedation and analgesia if necessary to reduce pain during the procedure. A reduction in pain also helps decrease guarding and abdominal muscular constriction, thereby lowering the intra-abdominal pressure and permitting easier reduction.

Wait 2-30 minutes. Some hernias self-reduce because of the application of cold compresses to reduce edema, the force of gravity, and relaxation of the muscles surrounding the hernia from sedation and analgesia.

Slowly apply pressure distal to the hernia while guiding the proximal portion into the abdomen through the fascial defect (see the images and the video below). Use two hands to facilitate guidance through the fascial defect and simultaneous gentle pressure. This part of the reduction can take 5-15 minutes. Too much distal pressure causes the hernia to balloon around the fascial opening, making reduction more difficult.

Slow constant pressure is applied to patient with left inguinal hernia.

Hernia content balloons over external ring when reduction is attempted.

Hernia can be reduced by medial pressure applied first.

Although some references recommend a truss for temporary closure of the fascial defect after successful hernia reduction, the efficacy of this measure has not been proved.

Ultrasonography (US) is certainly valuable in the diagnosis of a hernia and can be used to determine the contents of a hernia.[20]  One study that used computed tomography (CT) as the criterion standard showed a moderate sensitivity and high specificity for ultrasonographic diagnosis of incisional hernias.[21]  A smaller case review found US to be less useful in children.[22]

US has been advanced as an aid to hernia reduction.[23, 24, 25]  By assisting in reduction, it may reduce the rate of emergency repair for incarcerated hernias.[24]  The reasoning is that the ultrasound probe should be able to help locate the fascial defect, as well as the tissue to be reduced, and may give the operator a better grasp on the forces needed for reduction.

The suggested technique for US-assisted reduction (see the video below) includes the following steps:

• Position the patient as previously described (see Patient Preparation)
• Choose the high-frequency linear probe in two-dimensional mode; color Doppler may be applied if a distinction between strangulation and incarceration has not yet been established
• Identify the point of maximal aperture of the inguinal canal or fascial defect
• Hold the tissue perpendicular to the plane of maximal aperture, and guide it through
• Compress the tissue from a distal point while guiding the proximal end through the aperture

Youn et al reported a case in which laparoscopic reduction of an intersigmoid hernia, a rare form of internal hernia, was carried out in a 32-year-old man who presented with mechanical obstruction.[26] Herniation of small bowel through the intersigmoid recess was observed. The bowel was viable, and laparoscopic reduction of this incarcerated ileum was therefore performed. The patient recovered uneventfully, and the authors recommended that laparoscopic reduction of intersigmoid hernia be considered as an alternative technique for reduction.

Manual reduction can be complicated by worsened pain secondary to pressure and manipulation.

A reduction en masse, by which the existing peritoneal sac and constricting neck are reduced into the abdomen without relieving the constriction, is a serious complication.[27, 28, 29]  In such a case, the bowel progresses to obstruction and strangulation despite apparent reduction.[30]  The occult nature of reduction en masse may lead to delayed or missed diagnosis.

If strangulation is not recognized, gangrenous bowel can be reduced, which leads to peritonitis and sepsis.[7]

Retroperitoneal hematoma resulting from manual reduction of an indirect inguinal hernia has been reported.[31]

Umbilical hernia has been noted as a consequence of umbilical cord graft repair after hernia reduction in patients with gastroschisis. Taher et al reported the development of umbilical hernia in such patients even after preservation of the rectus fascia (two out of four patients); hence, a high index of suspicion is warranted in this setting.[32]

In a retrospective study that included 1763 cases of laparoscopic indirect inguinal hernia repair, Pan et al used propensity score matching analysis to investigate the effect of complete reduction and transection of the hernia sac on the formation of seromas.[33] ​ They found transection of the hernial sac to be significantly associated with postoperative seroma formation.