HERNIAS

A hernia is the name given to any organ or tissue that protrudes through a weakness in the parts that normally contain it. The most common hernias involve the intestine, which can protrude through a weakness in the abdominal wall. This weakness may be:

• a normal anatomical weakness found in everyone (e.g. the inguinal canal; the belly button)

• an abnormal weakness caused by a congenital defect or acquired as a result of injury or disease.

Acquired weaknesses often result from straining (e.g. when lifting heavy objects, coughing, being constipated), abdominal surgery, or through the laying down of fat in the overweight.

In the UK, over 80,000 hernia repair operations (hernior-rhaphy or hernioplasty) are carried out each year. Of these, around 10,000 are to repair a hernia that has recurred after previous surgery.

Men are 12 times more likely to develop a hernia than women and, overall, 3 per cent of adult males will eventually have a hernia repair. This is mainly because of the weakness opened up by the testes descending into the scrotum during development (see testicular descent and below). Another factor is the straining due to manual labouring jobs.

The important things your doctor needs to work out about any hernia is whether the bowel loop can be popped back into its normal place (reducible), whether it is trapped (irreducible) or whether its blood supply is in danger (strangulated).

A reducible hernia simply presents as a lump which is painless and often disappears when the person affected lies down. With a little gentle encouragement the lump can be massaged back into the abdomen. On coughing, it will protrude again and, if a hand is held over it, it will be felt to bulge as it transmits pressure. This is known as a cough impulse.

If the hernia cannot be coaxed back into the bowel (e.g. because of strands of fibrous scar tissue known as adhesions) it is irreducible. It is important to correct this surgically before it strangulates. A strangulation occurs when the opening through which the hernia protrudes becomes tight and constricts the circulation to the bowel. This causes symptoms of severe pain in the hernia itself, often of sudden onset (acute), or of central abdominal pain that comes and goes in waves as if the bowel is being squeezed (colicky). The pain may not be felt in the hernia itself due to the way the nerve endings connect up to the spinal cord.

Other symptoms of intestinal obstruction soon occur. These include vomiting, distension and bloating of the abdomen, noisy bowel sounds and absolute constipation. Not even wind can pass through the constricted hernia to be voided downwards. The hernia itself will feel tense and very tender. Overlying skin may become red, hot and inflamed in the later stages.

Figure 19: Hernia types. Inguinal, femoral, epigastric, umbilical and incisional hernias (in old operation scar) are the most common types.

A strangulated hernia is a surgical emergency. Even if strangulation is only suspected, medical advice should be sought without delay. If strangu-lation is not relieved urgently, so that blood circulation is restored, the loop of bowel will die and become gangrenous. This can cause life-threatening blood poisoning (septicaemia). The three commonest types of hernia to strangulate are, in order of frequency:

• femoral hernias

• indirect inguinal hernias

• umbilical hernias.

Congenital Inguinal Hernia

A congenital inguinal hernia is almost exclusively a male phe-nomenon related to the descent of the testes. Overall, 4 per cent of boys need surgical correction of a congenital inguinal hernia.

During the last few months of development, the testis travels from the abdomen into the scrotum by passing over the pubic bone. The testis passes obliquely through the lower abdominal wall into the scrotum. It carries layers of tissue with it to form a passageway known as the inguinal canal. The opening usually be-comes blocked off during development, but sometimes stays open by accident. A loop of bowel can then easily trail through into the scrotum to cause a bulge. Sometimes, a congenital inguinal hernia is also associated with an undescended testis.

Congenital inguinal hernias are prone to strangulation because of the narrowness of the inguinal canal through which they have passed. They are surgically corrected, usually around the age of one year unless symptoms develop which require prompt surgery. The bowel is gently pushed back into the abdomen, the pouch of peritoneum which formed the hernia sac is tied and cut, and the area reinforced to prevent a recurrence in future years.

Figure 20: A Testicle and its surrounding layers.

Acquired Inguinal Hernias

Acquired inguinal hernias are of two main types. If the bowel follows the anatomical weakness and passes through the whole inguinal canal, it is known as an indirect inguinal hernia. If the bowel pushes through the back wall of the inguinal canal to enter halfway down, it is called a direct inguinal hernia. This is because the hernia seems to protrude directly forwards.

An indirect inguinal hernia has to pass through two narrow openings at either end of the inguinal canal. It therefore often starts off small at the beginning of the day and gets larger once the sufferer has been up and about for a while. On lying down, it will also take time for the bowel to slither back into the abdomen (assuming the hernia is reducible). Because of the narrowness of the openings, an indirect hernia is liable to become irreducible or to strangulate.

A direct inguinal hernia, on the other hand, bulges forwards through a relatively large weakness in the abdominal wall. It therefore appears immediately on standing up and disappears as soon as the person affected lies down. A direct hernia hardly ever descends into the scrotum and, because the opening is large, strangulation is rare.

Sometimes, a direct and an indirect hernia exist in the same patient on the same side simultaneously.

Sixty per cent of inguinal hernias occur on the right-hand side, 20 per cent on the left, and 20 per cent are bilateral. They vary in size from small bulges to enormous masses stretching down to the knee.

Types of Inguinal Hernia Repair

Three quarters of inguinal repairs performed in the UK still involve an old-fashioned technique designed in 1884. It is now considered obsolete in many countries. This is Bassini's darn technique, in which loops of nylon thread are used to cobble up and repair the weakness in the abdominal wall. Only one layer of tissue is stitched through, and it breaks down in 10 per cent of cases. This is the main reason why repeat operations are so frequently needed in the UK.

Two newer and more effective operations are now available. In the Open Tension Free (or Lichtenstein) technique, a patch of polypropylene mesh is stitched in place over the rupture. This makes the repair stronger and less likely to break down than other methods. The risk of needing a recurrent operation is less than 1 per cent.

The Shouldice technique of hernia repair involves stitching through three overlapping layers of abdominal wall tissue rather than one ­ as in the traditional darn technique. The risk of this repair breaking down are also less than 1 per cent, and more and more British surgeons are now adopting this operative method.

There has been recent experimentation with a laparoscopic (keyhole) surgery technique in which the hernia is repaired from inside the abdominal cavity and the defect patched with a small piece of metal.

Old-fashioned trusses are belt-like contraptions designed to apply pressure over an area of weakness through which a hernia protrudes. This keeps the hernia in its place but can be cumbersome. Trusses are best for small direct inguinal hernias where the pad can be accurately placed over the area of weakness. They need to be replaced every few years as they wear out, stretch and become ineffective. They should not be used where a hernia is irreducible as this can cause pressure damage to the bowel and increase the risk of strangulation.

Hernia Repairs and Male Fertility

Recently, hernia repairs were linked with male subfertility. A study in Israel found that men who had had a previous hernia repair had a one in eight chance of a small, shrunken (atrophic) testis, compared with an incidence of less than 1 per 100 in men who had not had a hernia repair.

When semen was analysed, the quality was significantly poorer in men who had had a hernia repair, whether or not they had an atrophic testis. It is thought that testicular function is either affected by reduced blood supply (e.g. damage or scarring during the operation) or from some as yet unidentified immunological reaction. These results are being further investigated.

Recent studies in Germany found that half the 834 surgeons questioned routinely remove a testis as part of a hernia repair. This is obviously unacceptable to most men unless it is medically imperative (because the testis is diseased, atrophic or otherwise abnormal).

Femoral Hernia

A femoral hernia is a protrusion of a piece of intestine or fatty tissue through a weakness at the top of the leg. This weakness occurs where there is a natural gap, wide enough to admit a little finger, where the femoral vein, artery and nerve pass from the abdominal cavity into the leg.

Femoral hernias are most common in those over the age of 50. They are more common in women as their pelvises are wider, but do occur in men. They are often bilateral (occurring on both sides). Symptoms include a lump in the groin, sometimes with pain and discomfort. They frequently strangulate causing colicky pains, distension, vomiting and constipation. Once diagnosed, a femoral hernia needs urgent surgical repair because of this high risk of strangulation.

Umbilical Hernia

Umbilical hernias are protrusions of bowel related to the belly button (umbilicus). Congenital umbilical hernias form through the gap where the umbilical cord vessels enter the abdomen during foetal life. They are usually present at birth but may not be noticed until the umbilical cord separates and heals. They rarely cause symptoms and 90 per cent disappear during the first few years of life as umbilical scar tissue contracts and thickens. Repair is not usually attempted until the child is at least two years old.

Acquired umbilical hernias are common in the obese. Those hernias that protrude through umbilical scar tissue are usually caused by conditions that raise pressure inside the abdomen and distend it. This causes the bellybutton to bulge outwards. Treatment is not necessary unless the hernia is large or giving rise to unpleasant or painful symptoms.

Figure 21: Umbilical hernias

Acquired para-umbilical hernias protrude through a gap to one side of the umbilical scar and convert the belly button into a crescent-shaped slit. These do need repair as they cause pain and swelling around the umbilicus and can strangulate.

Incisional Hernia

Incisional hernias form through a weakness in the scar tissue formed after a previous operation, or area of trauma. Scar tissue is inelastic and stretches easily if put under constant strain ­ e.g. by lifting, chronic coughing or straining with constipation. It also becomes weaker with increasing age and if deficient in vitamin C. Complications after surgery such as wound infection or heavy bleeding also make scar tissue more likely to weaken.

Incisional hernias can be dissected and repaired surgically. If the patient is unfit for surgery, an abdominal belt (truss) is occasionally used.

Epigastric Hernia

An epigastric hernia is the protrusion of a piece of fat (and occasionally bowel) through a weakness in the mid-line between the umbilicus and the rib cage. This weakness is the natural line where the abdominal wall muscles meet. Symptoms usually include pain in the upper abdomen which often comes on after eating and is therefore frequently misdiagnosed as indigestion. Repair is a simple matter of sewing up the abdominal wall defect.

Hiatus Hernia

A hiatus hernia occurs when a section of the stomach, which usually lies in the abdominal cavity, protrudes through a gap (hiatus) in the diaphragm to enter the chest. It is more common in the overweight and in those who smoke. Occasionally, it is present from birth.

In 90 per cent of cases, the oesophagus and stomach slide upwards into the gap through which the oesophagus (gullet) passes, so that only the top end of the stomach is in the gap. This is known as a sliding hiatus hernia.

In 10 per cent of cases, part of the stomach rolls up into the gap alongside the oesophagus, so that both the oesophagus and part of the stomach are side by side in the gap. This is known as a rolling hiatus hernia.

Figure 22: Hiatus hernias

Hiatus hernias produce two sets of symptoms: those due to the extra bulk in the chest (coughing, shortness of breath, palpitations, feelings of pressure, hiccough) and those due to disruption of the valve system between the oesophagus and stomach (acid reflux, indigestion and burning sensations which are often worse on bending over or lying down). Usually, a rolling hiatus hernia does not cause symptoms of acid regurgitation because the valve mechanism between the stomach and oesophagus is not affected.

Many people have mild hiatus hernias without symptoms, which are never diagnosed.

Hiatus hernias are investigated by passing a flexible telescope down the throat while the patient is under light sedation. This procedure is called oesophagoscopy or gastroscopy. Occasion-ally, a barium X-ray is also used to see whether there is reflux of stomach contents into the oesophagus.

Treatment of hiatus hernias involves losing weight, which often improves symptoms, eating little and often (rather than large meals), avoiding bending or lying down after meals, giving up smoking and raising the head of the bed slightly to prevent reflux during sleep. Some patients find they can only sleep at night if propped fully upright.

Drugs such as antacids help to reduce heartburn and protect the delicate oesophagus (gullet) from acid damage. Prokinetic drugs encourage ordered contraction of stomach and intestinal muscles and are also useful in preventing acid regurgitation.

If symptoms are severe, surgery to repair the hiatus hernia is undertaken. This is a major operation in which the protruding stomach is brought back down into the abdomen and tethered into place.