What is Hernia

What Is Hernia:

                      A hernia is a protrusion of a viscus or part of a viscus through an abnormal opening in the wall of its containing cavity. The external abdominal hernia is the most common form, the most frequent varieties being the inguin

Figure:Hernia

Aetiology

                 Any condition that rises the intra-abdominal pressure such as powerful muscular efforts, may produce a hernia. Whooping cough is a predisposing cause in childhood, whereas chronic cough, straining on micturation or straining on defaecation may precipitate a hernia in adult. Hernias are more common in smokers, intra-abdominal malignancy can be a cause of hernia. Stretching of the abdominal musculature because of an increase in contents as in obesity can be another factor. Fat acts to separate muscle bundles and layers, weaken aponeuroses and favour the appearance of para-umbilical, direct inguinal and hiatus hernia. An indirect inguinal hernia may occur in a congenital preformed sac- the remains of the processus vaginalis.

Composition of hernia

                                      A hernia consists of three parts- the sac, the covering of the sac, and the contents of sac.

The sac- The sac is a diverticulum of peritoneum consisting of mouth, neck, body and fundus.

  The neck is usually well defined but in some direct inguinal hernia and many incisional hernias, there is no actual neck.

   The body of the sac varies greatly in size and is not necessarily occupied. In long standing case the wall of the sac may be comparatively thick.

The coverings of the sac-Coverings are derived from the layers of the abdominal wall through which the sac passes. In longstanding cases they become atrophied from stretching and so amalgamated that they are indistinguishable from each others.

Contents

                These can be-

• Omentum- Omentocele
• Intestine-   Enterocele
• A portion of circumference of the intestine- Richter’s hernia
• A portion of bladder may constitute part of or sole content of direct inguinal, a sliding inguinal or a femoral
• Ovary with or without the corresponding fallopian tube.
• A meckle’s diverticulum- a little’s hernia.
• Fluid as a part of ascites or residuum there of.

Classification- Irrespective of site, a hernia can be classified into five different types-

·         Reducible hernia- The hernia either reduces itself when the patient lies down or can be reduced by the patients or the surgeon. The intestine usually gurgles on reduction and the first portion is more difficult to reduce than the last. Omentum in contrast is described as doughy and the last portion is more difficult to reduce than the first. A reducible hernia imparts an expansile impulse on coughing.

·         Irreducible hernia- In this case the contents cannot be return to the abdomen but there is no evidence of other complications. It is usually due to adhesions between the sac and its contents or overcrowding with in the sac.

·         Obstructed hernia- This is an irreducible hernia containing intestine that is obstructed from without or within but there is no interference to the blood supply to the bowel. The symptoms are less severe and the onset more gradual than in strangulated hernia (colicky abdominal pain).

·         Incarcerated hernia- The term incarceration is often used loosely as an alternative to obstruction or strangulation but is correctly employed only when it is considered that the lumen of that portion of the colon occupying hernial sac is loaded with feces.

·         Strangulated hernia- A hernia becomes strangulated when the blood supply of its contents is seriously impaired, rendering the contents are ischaemic. Gangrene may occur as early as 5-6 hours after the onset of first symptoms. Although inguinal hernia may be 10 times more common than femoral hernia, a femoral is more likely to strangulate.

Pathology-

                 The intestine is obstructed and its blood supply impaired. Initially only the venous return is impeded; the wall of intestine becomes congested and bright red with the transudation of serous fluid into the sac. As congestion increases the wall of the intestine becomes purple in color. The intestinal pressure increase, distending the intestinal loop and impairing the venous return further. As venous stasis increase, the arterial supply becomes more and more impaired. Blood is extravasated under the serosa and is effused into the lumen. The fluid in the sac becomes blood stained and the shining serosa dull because of a fibrinous, sticky exudate. At this stage the walls of the intestine have lost their tone and becomes friable. Bacterial transudation   occurs secondary  to the lowered intestinal viability and the sac fluid becomes infected. Gangrene appears at the rings of constriction, which become deeply indented and grey in color. The gangrene then develops in the anti mesenteric border. The mesentery involved by the strangulation also becomes gangrenous. If the strangulation is unrelieved perforation of wall of the intestine occurs.

Clinical features

                            Sudden pain, at first situated over the hernia, is followed by generalized abdominal pain, colicky in nature and often located mainly at the umbilicus. Nausea and subsequently vomiting ensue. The patient may complain of an increase in hernia size. On examination, the hernia is tense, extremely tender and irreducible, and there is no expansile cough impulse.

Strangulated hernias

·         Present with local then general abdominal pain and vomiting.

·         A normal hernia can strangulate at any time.

·         Most common in hernias with narrow necks such as femoral hernias.

·         Require urgent surgery.

                          

Types of hernia

·         Reducible- Contents can be return to abdomen

·         Irreducible- Contents cannot be returned but there are no other complications.

·         Obstructed- bowel in the hernia has good blood supply but bowel is obstructed.

·         Strangulated- blood supply of bowel is obstructed.

·         Inflamed- contents of the sac have become inflamed.

  Natural history of hernias

·         Irreducible hernias-there is a risk of strangulation at any time

·         Obstructed hernias- usually go on to strangulation

·         Strangulated hernias-Gangrene can occur within 6 hours.

Richter’s hernia

                            Richter’s hernia is a hernia in which the sac contains only a portion of the circumference of the intestine (usually small intestine). It usually complicates femoral and rarely, obturator hernias.

Inflamed hernia

                           Inflammation can occur from inflammation of the contents of the sac, e.g. acute appendicitis or salphingitis, or from external cause, e.g. the tropic ulcers that develop in the dependent area of large umbilical or incisional hernias. The hernia is usually tender but not tense and the overlying skin red and edematous. Treatment is based on treatment of underlying cause.

Inguinal hernia

      Surgical anatomy- The superficial inguinal ring is a triangular aperture in the aponeurosis of the external oblique muscle and lies 1.25cm above the pubic tubercle.

      The deep inguinal ring is a U shaped condensation of the transversalis fascia and lies 1.25cm above the inguinal ligament, midway between the symphysis pubis and the anterior superior iliac spine. The transversalis fascia is the fascial envelope of the abdomen and the competency of the deep inguinal ring depends on the integrity of this fascia.

Figure:Inguinal Hernia

      The inguinal canal

                                      In infant the superficial and deep inguinal rings are superimposed and the obliquity of the canal is slight. In adult the inguinal canal which is about 3.75cm long and directed downwards and medially from the deep to superficial inguinal ring. In male the inguinal canal transmit the spermatic cord, the ilio-inguinal nerve and the genital branch of genito-femoral nerve. In the female the round ligament replaces the spermatic cord. The anterior boundary comprises mainly the external oblique aponeurosis with the conjoined muscle laterally. The posterior boundary is formed by the fascia transversales and the conjoined tendon. The inferior epigastric vessels lie posteriorly and medially to the deep inguinal ring. The superior boundary is formed by the conjoined muscle and the inferior boundary is the inguinal ligament.

         An indirect inguinal hernia travels down the canal on the outer side of the spermatic cord. A direct hernia comes out directly towards directly forwards through the posterior wall of the inguinal canal. The neck of the indirect inguinal hernia is lateral to the inferior epigastric vessels, the direct hernia usually emerges medial to this.

  Natural history of inguinal hernia

• Inguinal hernia in babies are the result of a persistent processus vaginalis.
• Indirect inguinal hernia is the most common hernia of all specially in the young.
• Direct inguinal hernia becomes more common in the elderly.

Indirect (oblique) inguinal hernia

                                                        This is the most common form of hernia. Indirect hernias are most common in the young whereas direct hernias are most common in the old. In the first decade of life, inguinal hernia is more common on the right side in the male. In adult males 65% of the inguinal hernias are indirect and 55% are right sided. The hernia is bilateral in 12% of cases.

Natural history of inguinal hernias

·         Inguinal hernias in babies are the result of a persistent processus vaginalis

·         Indirect inguinal hernia is the most common hernia of all, specially in the young

·         Direct inguinal hernia becomes more common in the elderly.

 Types of indirect inguinal hernia

1)       Bubonocele-The hernia is limited to the inguinal canal.

2)       Funicular -  the processus vaginalis is closed just above the epididymis. The contents of the sac can be felt separately from the testes,which lies below the hernia.

3)       Complete – A complete inguinal hernia is rarely present at birth but is commonly encountered in infancy. It also occurs in the adolescence or in adulthood. The testis appears to lie within the lower part of the hernia.

Differential diagnosis in the male 

• Vaginal hydrocele
• Encysted hydrocele of the cord
• Spermatocele
• Femoral hernia
• Incompletely descended testis in the inguinal canal- an inguinal hernia is often associated with this condition;
• Lipoma of the cord

Differential diagnosis in the female

• Hydrocele of the canal of Nuck
• Femoral hernia.

Treatment

                  Operation is the treatment of choice.

Treatment of hernias

• Surgery is the treatment of choice
• Surgery is either open or laparoscopic
• Any hernia can strangulate.

Direct inguinal hernia

                                      In adult 35% of the inguinal hernia are direct. A direct inguinal hernia is always acquired. The sac passes through a weakness or defect of transversalis fascia in the posterior wall of the inguinal canal. In some cases the defect is small and is represented by a discrete in the transversalis fascia, whereas in others there is a generalized bulge.

    Direct hernias do not often attain a large size or descend into the scrotum. In contrast to an indirect inguinal hernia, a direct inguinal hernia lies behind the spermatic cord. The sac is often smaller than the hernial mass would indicate, the protruding mass mainly consisting of extra-peritoneal fat. As the neck of the sac is wide, direct inguinal hernias do not often strangulate.

Direct inguinal hernias

• All are acquired
• They are most common in older man
•  They rarely strangulate

Operation for direct inguinal hernia

                                                             The principles of repair of direct inguinal hernias are the same as those of indirect hernia, with the exception that the hernia sac can usually be simply inverted after it has been dissected free and the transversalis fascia reconstructed in front of it. The reconstruction of the posterior wall of the inguinal canal should be undertaken by the Shouldice repair or by using a mesh implant according to the Lichtenstein technique. The ‘Bassini’ darn operation is no longer acceptable because of its high recurrence rate and slow rehabilitation.

Sliding hernia (hernia-en-glissade)

                                                        As a result of  slipping of the posterior parietal peritoneum on the underlying retroperitoneal structures, the posterior wall of the sac is not formed of peritoneum alone, but the sigmoid colon and its mesentery on the left side, the caecum on the right side and sometimes on either side by a portion of the bladder.

  Clinical features

                             A sliding hernia occurs almost exclusively in men. Five out of six sliding hernias are situated on the left side; bilateral sliding hernias are rare. The patient is always over 40 years of age, the incidence rising with age. It should be suspected in a very large globular inguinal hernia descending well into the scrotum.

   Treatment

                      A sliding hernia is impossible to control with a truss and as a rule, the hernia is a cause of considerable discomfort. Consequently, operation is indicated and the result is very good.