Abdominal wall and hernia

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CHAPTER 12 Abdominal wall and hernia

Herniae 195
Other conditions of the abdominal wall 202
Swellings in the groin and scrotum 203

Herniae

A hernia is an abnormal protrusion of a viscus or part of a viscus through an opening in the cavity in which it is normally contained. About 75% of all herniae occur at the groin.

Reducible hernia

This is one in which the contents of the sac reduce spontaneously or can be pushed back manually.

Irreducible hernia

The contents cannot be returned to the peritoneal cavity either because there are adhesions between the sac and contents or because of the narrow neck of the sac. Irreducible herniae may be as described below:

Incarcerated

There are adhesions between the sac and the contents, but there is no obstruction or interference with blood supply. The hernia simply will not reduce.

Obstructed

A hollow viscus is trapped within the sac and obstruction occurs. The blood supply remains intact. This is a common cause of small bowel obstruction.

Strangulated

The arterial blood supply to the contents of the sac is compromised such that unless surgical relief is undertaken the contents of the sac will become gangrenous.

General description of a hernia (→ Fig. 12.1)

image

Figure 12.1 (A) General description of a hernia. (B) Principles of repair.

Defect

This is in the abdominal wall (e.g. at the deep inguinal ring or femoral ring) or a defect in a surgical incision (incisional hernia).

Sac

This has a neck (which may be very narrow), a body and a fundus.

Contents of the sac

May be omentum, bowel, ovary, etc.

Classification of hernia

Congenital

A congenital hernia develops in a peritoneal sac, which gives rise to a hernia in infancy, or provides a potential channel for one to form in later life, e.g. patent processus vaginalis in indirect inguinal hernia, or failure of closure of the umbilicus orifice in umbilical hernia. These sacs represent persistent embryological channels.

Acquired

Aetiological factors

• Loss of tissue strength and elasticity, e.g. direct inguinal hernia in the older patient
• Surgical trauma, e.g. incisional hernia
• Enlargement of a foramen, e.g. enlarged oesophageal hiatus allowing development of a hiatus hernia
• Nerve damage with consequent weakening of muscles, e.g. development of inguinal hernia after appendicectomy owing to damage to the ilioinguinal nerve.

If a potential weakness is present, then the following factors may predispose to hernia formation by increasing intra-abdominal pressure. These include:

• Heavy lifting or carrying
• Coughing, e.g. asthma, COPD
• Constipation
• Benign prostatic hypertrophy
• Pregnancy
• Obesity
• Ascites
• CAPD – may unmask persistent processus vaginalis with CAPD fluid filling a potential hernial sac and presenting as scrotal oedema.

Types of hernia

Inguinal hernia

This is the most common form of hernia. There are two types: indirect and direct.

Indirect

A peritoneal sac protrudes through the deep inguinal ring, passes down the inguinal canal, and may extend as far as the upper pole of the testis. The defect is congenital and is due to a persistent processus vaginalis. It is more common in males. It may appear in infancy or early adult life. In infants, there is often an associated hydrocele and undescended testis.

Direct

This is acquired. The defect occurs in the abdominal wall, in Hesselbach’s triangle (bounded by the inguinal ligament inferiorly, the inferior epigastric artery laterally and the lateral border of rectus muscle medially). It is due to a weakness of the transversalis fascia in the posterior wall of the inguinal canal. It is often bilateral and occurs in the older patient and may be associated with obesity, cough, constipation, prostatism.

Both types may occur and straddle the inferior epigastric artery, the so-called ‘pantaloon’ hernia.

Symptoms and signs

Often none. Occasionally aching or dragging sensation in the groin. Some patients relate the development of the hernia to an episode of straining or lifting. Some patients can push the hernia back. A painful, tense, tender lump that will not reduce indicates incipient strangulation until proved otherwise. Examine the patient standing. A hernia that descends into the scrotum is likely to be indirect. A diffuse bulge medially over the canal is likely to be direct. Locate the pubic tubercle. If the hernia is above and medial to this it is an inguinal hernia, if it is below and lateral, it is a femoral hernia. Test for a cough impulse. Lay the patient down and reduce the hernia. Apply pressure over the deep inguinal ring, i.e. 1 cm above the midpoint of the inguinal ligament. Ask the patient to cough. If the hernia appears medial to the point of pressure, it is likely to be direct. If no hernia appears, release the pressure and again get the patient to cough. If it appears, it is likely to be indirect. For smaller herniae it is possible to distinguish between direct and indirect by invaginating the scrotum with the little finger into the inguinal canal. Get the patient to cough. If the hernia is indirect, the impulse hits the tip of the finger; if direct, it hits the pulp. The difference, in fact, is academic since both will be carefully looked for at surgery.

Treatment

Uncomplicated

Elective herniotomy (i.e. excision of sac) in children. Herniotomy and herniorrhaphy (repair of the defect) in adults. There are three accepted methods of repair of inguinal hernia:

1. Lichtenstein repair – this is a tension-free mesh repair using polypropylene mesh.
2. Shouldice repair – this is a double-breasted repair of the transversalis fascia followed by suturing of the conjoint tendon to the inguinal ligament with non-absorbable sutures.
3. Laparoscopic – this may be via an extraperitoneal or intraperitoneal technique. NICE guidelines recommend this technique for bilateral or recurrent inguinal herniae.

Trusses may be used if surgery is contraindicated. A spring-loaded pad is applied to the defect after the hernia has been reduced. The patient should apply it after lying down and reducing the hernia. They are uncomfortable and unhygienic. Indications for a truss are rare.

Obstructed and strangulated herniae

These require emergency surgery, with resection of bowel if necessary followed by surgical repair.

Procedure

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