Hernias 

Definition – a hernia is an abnormal protrusion from one anatomical space to another. Abdominal wall hernias are among the most common of all surgical problems in humans. They are a leading cause of work loss and disability and are sometimes lethal.

• About 75% of hernias occur in the groin (indirect inguinal, direct inguinal, femoral); incisional and ventral hernias comprise about 10%; umbilical 3%; and others about 3%

• Generally, a hernia is a mass composed of covering tissues (skin, subcutaneous tissues etc), a peritoneal sac, and any contained viscera

• A reducible hernia is one in which the contents of the sac return to the abdomen spontaneously or with manual pressure when the patient is recumbent

• An irreducible hernia (aka incarcerated) is one whose contents cannot be returned to the abdomen, usually because they are trapped by a narrow neck
  • The term incarceration does not imply obstruction, inflammation or ischemia of the herniated organs, though incarceration is necessary for obstruction or strangulation to occur

• Compromise to the blood supply of the contents of the sac (e.g. omentum or intestine) results in a strangulated hernia, in which gangrene of the contents of the sac have occurred

• An uncommon and dangerous type of hernia, a Richter hernia occurs when only part of the circumference of the bowel becomes incarcerated or strangulated in the fascial defect

Types of Hernias

Indirect and Direct Inguinal Hernias

• Indirect hernias pass through the internal inguinal ring and, if large, out through the external ring
• Direct hernias push their way directly forward through the posterior wall of the inguinal canal, into a defect in the abdominal wall

Characteristic	Direct (Acquired )	Indirect (Congenital)
Predisposing Factors	Weakness of anterior abdominal wall in inguinal triangle (e.g. owing to distended superficial ring, narrow inguinal falx, or attenuation of aponeurosis in males >40)	Patency of processus vaginalis (complete or at least superior part) in younger persons, the greater majority of which are males
Frequency	Less common (1/3 to ¼ of inguinal hernias)	More common (2/3 to ¾)
Exit from Abdominal Cavity	Peritoneum plus transversalis fascia	Peritoneum of persistent processus vaginalis plus all three fascial coverings or cord/round ligament
Course	Passes through or around inguinal canal, usually traversing only medial third of canal, external and parallel to vestige of processus vaginalis	Transverses inguinal canal (entire canal if it is of sufficient size) within processus vaginalis
Exit from Anterior Abdo Wall	Via superficial ring, lateral to cord; rarely enters scrotum	Via superficial ring inside cord; commonly passing into scrotum/labium majus
Other Features	Rarely strangulate	Can strangulate easily

Signs and Symptoms

• Most are asymptomatic until they produce a lump or swelling in the groin, though some patients may describe a sudden pain or bulge that occurred while lifting or straining
• In general direct hernias produce fewer symptoms than indirect hernias 
• Examination of the groin reveals a mass that may or may not be reducible – the patient should be examined both supine and standing and coughing or straining
• The external ring can be identified by invaginating the scrotum and palpating with the index finger
• Distinguishing between direct and indirect is of little use clinically because both need to be repaired  and both repairs take the same time

DDx

• Inguinal hernia must be differentiated from hydrocele of the spermatic cord, lymphadenopathy, or abscess of the groin, varicocele, and residual hematoma following trauma or spontaneous haemorrhage
• The presence of an impulse in the mass with coughing, bowel sounds in the mass, and failure to transilluminate are features which indicate an irreducible mass is a hernia

Tx

• They should always be repaired unless there are specific contraindications
• Painful, incarcerated or tender hernias usually require emergency operations due to the risk of strangulation

Femoral

• A femoral hernia descends through the femoral canal beneath the inguinal ligament
• Because of its narrow neck, it is prone to incarceration and strangulation
• Femoral hernia is much more common in women than in men, but in both sexes femoral hernia is less common than inguinal hernia

Signs

• A femoral hernia may present in a variety of different ways – if it is small and uncomplicated, it usually appears as a small bulge in the upper medial thigh just below the level of the inguinal ligament

Treatment

• The principles of femoral hernia repair (for all you budding surgeons) are: (1) complete excision of the hernia sac, (2) the use of non-absorbable sutures, (3) repair of the defect in the transversalis fascia that is responsible for the hernia, and (4) use of Cooper’s ligament for the repair

Umbilical Hernias

• Umbilical hernia in adults occurs long after closure of the umbilical ring and is due to a gradual yielding of the cicatrical tissue closing the ring
• It is more common in women than in men
• Predisposing factors include multiple pregnancies with prolonged labour, ascites, obesity and large intra-abdominal tumours

Clinical Findings

• The hernia usually steadily increases in size; the hernia sac may have multiple loculations
• Emergency repair is often necessary because the neck of the hernia is quite narrow compared to the size of the herniated mass

Treatment

• Umbilical hernia should be repaired expeditiously to avoid incarceration and strangulation
• The presence of cirrhosis and ascites should not discourage repair since the consequences of strangulation are particularly dangerous in these patients

Epigastric Hernia

• An epigastric hernia protrudes through the linea alba above the level of the umbilicus
• The hernia may develop through one of the foramina of egress of the small paramidline nerves and vessels, or through an area of congenital weakness in the linea alba
• They are more common in men than in women and most common between the ages of 20 and 50

Signs

• If a mass is palpable, the diagnosis can often be confirmed by any maneuver that will increase intra-abdominal pressure and thereby cause the mass to bulge anteriorly

Treatment

• Most should be repaired; the recurrence rate is 10-20% most likely due to failure to repair small defects

Incisional Hernia

• These follow the breakdown of muscle closure after previous surgery

Spigelian Hernia

• These are acquired ventral hernias that occur through the linea semilunaris – nearly always found above the level of the inferior epigastric vessels

Littre’s Hernia

• Is a hernia that contains a Meckel diverticulum in the hernia sac

Maydl’s Hernia

• This involves a herniating “double loop” of bowel – the strangulated portion may reside as a single loop inside the abdominal cavity

Obturator Hernias

• These occur through the obturator canal – most lethal of all abdominal hernias 🡪 elderly women!
• Most commonly present as small bowel obstruction with cramping pain and vomitin

Lumbar or Dorsal Hernia

• These are hernias through the posterior abdominal wall at some level in the lumbar region
• A lump in the flank is the most common complaint, associated with a dull, heavy, pulling feeling

Extra – Acute Intestinal Obstruction

• In 75% of patients acute intestinal obstruction results from previous abdominal surgery secondary to adhesive bands or internal or external hernias
• Other causes of intestinal obstruction not related to surgery include lesions intrinsic to the wall of the intestine (e.g. diverticulitis, carcinoma, regional enteritis) and luminal obstruction (e.g. gallstone, tumour, intussusceptions)
• N.B. two other conditions that must be differentiated from AIO include adynamic (paralytic) ileus and primary intestinal pseudo-obstruction
  • Adynamic ileus is mediated via the hormonal component of the sympathoadrenal system and may occur after peritoneal insult
    • HCL, pancreatic enzymes and colonic contents are among the most irritating substances
    • It occurs to some degree after any abdominal operation
    • Thoracic diseases, including lower lobe pneumonia, fractured ribs and MI frequently produce the disorder
    • Intesinal ischaemia may perpetuate adynamic ileus
  • Intestinal pseudo-obstruction is a chronic motility disorder that mimics mechanical obstruction
    • This condition is exacerbated by narcotics use

Pathophysiology

• Distension of the intestine is caused by the accumulation of gas and fluid proximal to and within the obstructed segment
  • Because 70-80% of intestinal gas is swallowed air (composed mainly of nitrogen) removal of air by continuous gastric suction is a useful adjunct in the treatment
• The accumulation of fluid proximal to the obstruction results not only from ingested fluid, swallowed saliva, gastric juice and biliary and pancreatic secretions, but also from interference to normal Na and H2O transport
• The loss of fluids and electrolytes may be extreme, and unless replacement is prompt, hypovolemia, renal insufficiency, and shock may result
• The most feared complication of acute intestinal obstruction is the presence of a closed loop 🡪 that is when the lumen is occluded at two points by a single mechanism
  • During peristalsis, when a closed loop is present, pressures reach 30-60 cmH2O (normal = 2-4 cmH2O)
• Strangulation of the closed loop is common with marked proximal distension

Symptoms

• Mechanical intestinal obstruction is characterized by cramping, mid-abdominal pain, which tends to be more severe, the higher the obstruction
• When strangulation is present the pain is usually more localized and may be steady and severe without a colicky component
• Vomiting is almost invariable – and it is earlier and more profuse the higher the obstruction
  • The vomitus initially contains bile and mucus and remains as such if the obstruction is high in the intestine
  • With low ileal obstruction, the vomitus becomes feculent

Physical Findings

• Abdominal distension is the hallmark – it is least marked in cases of obstruction high in the intestine and most marked in colonic obstruction
• In early obstruction tenderness and rigidity are usually minimal; the appearance of shock, tenderness, rigidity, and fever indicates that contamination of the peritoneum with infected intestinal content has occurred
• A quite abdomen does NOT eliminate the possibility of obstruction! (nor does it establish the diagnosis of adynamic ileus)

Lab and X-Ray Findings

• Laboratory and clinical findings are used to help differentiate the two important clinical aspects of this disorder: strangulation vs. non-strangulation and partial vs. complete obstruction
• Leukocytosis usually occurs when strangulation is present! (but a normal WBC count does not exclude)
• Roentgenographic studies demonstrating fluid and gas-filled loops of small intestine usually arranged in a ‘step ladder’ pattern with air-fluid levels and an absence or paucity of colonic gas are pathognomonic for small bowel obstruction