A hernia is a protrusion of an organ or tissue through a weak area in the muscle or tissue that normally contains it. The term is usually applied to a protrusion of the intestine important are inguinal hernias, which mainly affect men; femoral hernias, which are more common in overweight women; and umbilical hernias, which occur in babies.

Symptoms and treatment 

The first symptom of an abdominal hernia is usually a bulge in the abdominal wall. There may also be some abdominal discomfort. Sometimes the protruding intestine can be pushed back into place (known as a reducible hernia). In other cases, however, the hernia bulges out and cannot be put back (an irreducible hernia). This condition is painful, and surgery is usually necessary to repair the weakened area (see hernia repair). If the trapped portion of intestine becomes twisted, the blood supply to the area will be impaired. This problem, known as a strangulated hernia, needs urgent treatment, otherwise gangrene of the bowel may develop. Umbilical hernias in babies can usually be left untreated as they tend to disappear naturally by age five. 

Hernia repair

Surgical correction of a hernia. Surgery is usually performed to treat a hernia of the abdominal wall that is painful or cannot be pushed back into place. A strangulated hernia (in which the blood supply to a trapped portion of intestine is cut off) requires an emergency operation. During surgery, the protruding intestine is pushed back into the abdomen and the weakened muscle wall strengthened. Either open or minimally invasive surgery, using an endoscope to repair the hernia from within the abdominal cavity, may be used.

Hernia in more detail 

"No disease of the human body, belonging to the province of the surgeon, requires in its treatment a better combination of accurate anatomical knowledge with surgical skill than Hernia in all its varieties."  Sir Astley Paston Cooper (1804).

A hernia is a protrusion of a viscus or part of a viscus through an abnormal opening in the walls of its containing cavity. The external abdominal hernia is the most common form, the most frequent varieties being the inguinal, femoral and umbilical, accounting for 75% of cases. The rarer forms constitute 1.5%, excluding incisional hernias.

General features common to all hernias

Aetiology

Any condition that raises intra-abdominal pressure, such as a powerful muscular effort, may produce a hernia.

Whooping cough is a predisposing cause in childhood, whereas a chronic cough, straining on micturition or straining on defaecation may precipitate a hernia in an adult.

Hernias are more common in smokers, which may be the result of an acquired collagen deficiency increasing an individual’s susceptibility to the development of hernias.

It should be remembered that the appearance of a hernia in an adult can be a sign of intra-abdominal malignancy. 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, weakens aponeuroses and favours the appearance of paraumbilical, direct inguinal and hiatus hernias.

A femoral hernia is rare in men and nulliparous women but more common in multiparous women due to stretching of the pelvic ligaments. An indirect hernia may occur in a congenital preformed sac – the remains of the processus vaginalis.

Peritoneal dialysis can cause the development of a hernia from a previously occult weakness or enlargement of a patent processus vaginalis

Causes of hernias

• Coughing
• Straining
• Obesity
• Intra-abdominal malignancy

Diagram below: Locations of herniae

Composition of a hernia

As a rule, a hernia consists of three parts – the sac, the coverings of the sac and the contents of the 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 hernias and in many incisional hernias there is no actual neck. The diameter of the neck is important because strangulation of bowel is a likely complication when the neck is narrow, as in femoral and paraumbilical hernias.

The body of the sac varies greatly in size and is not necessarily occupied. In cases occurring in infancy and childhood, the sac is gossamer thin. In longstanding cases the wall of the sac may be comparatively thick.

The covering

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 other.

Contents

These can be:

• omentum = omentocele (synonym: epiplocele);
• intestine = enterocele; more commonly small bowel but may be large intestine or appendix;
• a portion of the circumference of the intestine = Richter’s hernia;
• a portion of the bladder (or a diverticulum) may constitute part of or be the sole content of a direct inguinal, a sliding inguinal or a femoral hernia;
• ovary with or without the corresponding fallopian tube;
• a Meckel’s diverticulum = a Littre’s hernia;
• fluid, as part of ascites or as a residuum thereof.

Classification

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

Types of hernia

• Reducible – contents can be returned 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 sac have become inflamed

Reducible hernias

The hernia either reduces itself when the patient lies down or can be reduced by the patient 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 returned 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 within the sac. Irreducibility without other symptoms is almost diagnostic of an omentocele, especially in femoral and umbilical hernias. Note that any degree of irreducibility predisposes to strangulation.

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 (colicky abdominal pain and tenderness over the hernia site) are less severe and the onset more gradual than in strangulated hernias, but more often than not the obstruction culminates in strangulation. Usually there is no clear distinction clinically between obstruction and strangulation and the safe course is to assume that strangulation is imminent and treat accordingly.

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 a hernial sac is blocked with faeces. In this case, the scybalous contents of the bowel should be capable of being indented with the finger, like putty.

Strangulated hernia

A hernia becomes strangulated when the blood supply of its contents is seriously impaired, rendering the contents ischaemic. Gangrene may occur as early as 5–6 hours after the onset of the first symptoms. Although inguinal hernia may be 10 times more common than femoral hernia, a femoral hernia is more likely to strangulate because of the narrowness of the neck and its rigid surrounds.

Pathology

The intestine is obstructed and its blood supply impaired. Initially, only the venous return is impeded; the wall of the 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 colour. The intestinal pressure increases, distending the intestinal loop and impairing venous return further. As venous stasis increases, 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 become 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 colour. The gangrene then develops in the anti-mesenteric border, the colour varying from black to green depending on the decomposition of blood in the subserosa. The mesentery involved by the strangulation also becomes gangrenous. If the strangulation is unrelieved, perforation of the wall of the intestine occurs, either at the convexity of the loop or at the seat of constriction. Peritonitis spreads from the sac to the peritoneal cavity.

Clinical features

Sudden pain, at first situated over the hernia, is followed by generalised abdominal pain, colicky in character 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.

Unless the strangulation is relieved by operation, the spasms of pain continue until peristaltic contractions cease with the onset of ischaemia, when paralytic ileus (often the result of peritonitis) and septicaemia develop. Spontaneous cessation of pain must be viewed with caution, as this may be a sign of perforation.

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.

Strangulated Richter’s hernia

Strangulated Richter’s herni is particularly noteworthy as operation is frequently delayed because the clinical features mimic gastroenteritis. The local signs of strangulation are often not obvious, the patient may not vomit and, although colicky pain is present, the bowels are often opened normally or there may be diarrhoea; absolute constipation is delayed until paralytic ileus supervenes. For these reasons, gangrene of the knuckle of bowel and perforation have often occurred before operation is undertaken.

Strangulated omentocele

The initial symptoms are in general similar to those of strangulated bowel. Vomiting and constipation may be absent as omentum, unlike intestine, can exist on a very meagre blood supply. The onset of gangrene is therefore delayed, occurring first in the centre of the fatty mass. Unrelieved, a bacterial invasion of the ischaemic contents of the sac will occur and an abscess eventually develops. In an inguinal hernia, infection usually terminates as a scrotal abscess, but extension from the sac to the general peritoneal cavity is always a possibility.

Inflamed hernia

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

Inguinal hernias

Introduction

In various countries of the world, inguinal hernias are between 8 and 20 times more common than femoral hernias. They are 10 times more common in males than females, and 55 per cent occur on the right side. Seventy per cent of inguinal hernias are indirect and 30 per cent direct. Bilateral hernias are four times more often direct than indirect. Approximately 85 000 inguinal hernias are repaired each year in the National Health Service in England, and 750 000 in the United States.

Inguinal hernias are present at birth in 3 to 5 per cent of full-term babies and up to 30 per cent of preterm babies. Of infants presenting with a congenital inguinal hernia, 10 to 20 per cent will have a contralateral hernia. Approximately 80 inguinal hernia repairs per 10 000 live births are performed in infants aged under 1 year. Rates for hernia surgery have a second peak in the 55- to 85-year age group, in which 75 hernia repairs per 10 000 population are performed yearly.

Aetiology

Indirect inguinal herniation arises from incomplete obliteration of the patent processus vaginalis. Not all individuals with a patency will develop a hernia; at autopsy 15 to 30 per cent of adult males without clinically apparent hernia have a patent processus vaginalis. Other factors that raise intra-abdominal pressure, such as continuous ambulatory peritoneal dialysis, ascites, respiratory and urinary-outflow obstruction, may exacerbate the development of groin hernias.

Patients with connective-tissue disorders such as Ehlers–Danlos syndrome have a high incidence of hernias, and smokers with groin hernias have been shown to have abnormalities of collagen metabolism resulting in a generalized weakness of connective tissue. Genetic factors are important in the aetiology of inguinal hernia: a study of congenital indirect inguinal hernias in China on 280 families indicated that the mode of transmission was autosomal dominant, with incomplete penetrance and paternal transmission. Affected males may inherit a gene associated with indirect inguinal hernia from their fathers. Many patients recall an episode of heavy manual work such as lifting in the development of their inguinal hernia. However, the underlying weakness and predisposing cause (e.g. indirect sac, smoking) is probably a more important contributory factor.

Anatomy

The inguinal canal

The inguinal canal passes obliquely downwards and medially from the internal to the external inguinal ring. It is 4 cm long in the adult, but in the neonate the deep ring lies posterior to the external ring. In the male the inguinal canal contains the spermatic cord and the ilioinguinal nerve; in the female it contains the round ligament and the ilioinguinal nerve. The anterior wall of the inguinal canal is formed by the aponeurosis of the external oblique; it is reinforced in the lateral third by the fibres of the internal oblique muscle. The posterior wall of the inguinal canal is formed by the transversalis fascia; it is reinforced in the medial third by the conjoint tendon, which is the fused tendon of the internal oblique and transversus abdominis muscles.

The inferior wall of the inguinal canal is formed by the in-rolled edge of the inguinal ligament. The superior wall is formed by the arching fibres of the internal oblique and transversus abdominis.

Internal inguinal ring

This is where the round ligament or spermatic cord emerge through the transversalis fascia. Medial to the inguinal ring are the inferior epigastric vessels. The surface markings of the internal ring are 1.25 cm above a point midway between the anterior superior iliac spine and the pubic tubercle.

External inguinal ring

The external ring is a V-shaped opening immediately superior to the pubic tubercle.

Symptoms and signs

A groin hernia may present as a lump in the groin that first appears in some patients after an episode of heavy lifting. Approximately 7 per cent of patients report a sudden event that could have caused the hernia. Often the hernia is noticed during standing or straining; typically the patient is aware that the lump disappears on lying down and is uncomfortable after exertion. Symptoms caused by complications of the hernia, such as abdominal distension and colicky abdominal pain, may be noticed by the patient before they notice the groin lump.

It is important to take a full history because hernias can develop as a result of raised intra-abdominal pressure such as occurs with respiratory, urinary or bowel problems, or during peritoneal dialysis.

Examination

A patient with a suspected groin hernia should be examined both lying and standing. They should be asked to cough so that a cough impulse and change in size of the hernia may be detected.

On inspection, a lump or bulge in the groin is noted, and this may be smaller or disappear when the patient is supine. It may be just in the groin or may extend down into the scrotum. It may be reducible or irreducible. If the hernia extends into the scrotum, it must be distinguished from a hydrocele or testicular swelling. An inguinal hernia is reduced through the superficial inguinal ring, which lies above and medial to the pubic tubercle. This distinguishes it from a femoral hernia, in which the neck of the hernia is below and lateral to the pubic tubercle. An indirect hernia can usually be controlled by pressure over the deep ring; a direct one, however, cannot, as it emerges forwards through the posterior wall of the inguinal canal medial to the deep ring.

Percussion and auscultation may be performed to determine whether the hernia contains bowel.

Diagnosis

An inguinal hernia is usually diagnosed on history and examination; further investigations are not generally required. However, in patients who have a typical history yet a hernia cannot be palpated, further investigations may be required. The differential diagnosis of an inguinal hernia is femoral hernia, hydrocele, undescended testicle, lymph nodes, lipoma, aneurysm of the femoral artery, and saphena varix.

Direct and indirect hernias

Inguinal hernias may be either indirect, the neck of the hernia emerging lateral to the inferior epigastric vessels and following the course of the inguinal canal, or direct, in which the sac emerges medial to the inferior epigastric artery.

Indirect hernias occur at all ages; direct hernias are more common in the over-40 age group. It was once thought to be an important clinical skill to be able to demonstrate the difference between the two types; however, this is notoriously inaccurate and expert surgeons have an accuracy of only 50 per cent in distinguishing between indirect and direct inguinal hernias.

Direct hernias have a smaller risk of strangulation than indirect hernias, owing to their wider necks. Indeed the repair of an easily reducible, confidently diagnosed, direct inguinal hernia, usually presenting as a prominent bulge in the groin of an elderly man, is not considered mandatory.

Further investigations

Herniography has been used for many years in the diagnosis of suspected, but impalpable, groin hernias. It involves puncture of the abdominal wall and injection of non-ionic contrast medium into the peritoneal cavity. It is highly accurate in experienced hands, but is an invasive procedure. It is also useful in distinguishing between direct and indirect hernias.

Computed tomographic scanning is a useful, non-invasive method of imaging groin hernias. It is possible to distinguish between direct and indirect hernias, but it is thought to be less sensitive when compared with herniography, and is expensive.

The role of magnetic resonance imaging in the diagnosis of impalpable hernias of the groin is yet to be fully evaluated. A recent study using dynamic real-time imaging was accurate in diagnosing impalpable hernias and was able to demonstrate the hernial sacs moving in and out of the defect.

Treatment

Surgery is the usual treatment for groin hernias, and with the use of local anaesthesia few patients should be refused surgery. Selected patients who do not wish to have surgery or who wish to work whilst awaiting surgery can be offered a truss.

Non-operative treatment is recommended only for asymptomatic, reducible, direct hernias in elderly individuals where an improvement in quality of life is unlikely. Some hernias enlarge and become symptomatic, particularly the indirect, sliding type; in such cases, and particularly in younger patients, surgery should be advised.

Trusses

Trusses have been used in the treatment of groin hernias for many years; approx. 40 000 are prescribed per annum in the United Kingdom. Trusses are appliances designed to be worn throughout the day to keep the hernia reduced. There are two main types: elastic trusses, which need replacing every 6 months, and spring trusses, which need to be renewed every 2 years. It is essential that the truss be correctly measured for and fitted if it is to benefit the patient. Patients must be fully instructed on how to fit and wear their truss. There is no evidence to suggest that truss wearing causes increased risk of recurrence after hernia surgery.

Surgical principles

The main principles of hernia surgery are herniotomy: opening and dealing with the hernia sac, and herniorrhaphy: repair of the posterior wall of the inguinal canal.

Herniotomy

A transverse or oblique skin incision is made 1 to 2 cm above the inguinal ligament and the external oblique aponeurosis is opened along the line of its fibres to the external inguinal ring. The hernial sac is dissected out from the cord structures and, if indirect, is carefully dissected up to the deep inguinal ring. The sac is opened, the contents are inspected, and reduced into the abdominal cavity. The sac is then transfixed and excised. If the sac is large and extends down into the scrotum, it is divided proximally; it is not necessary to dissect out the whole sac from the scrotum, which may actually be harmful and compromise the blood supply to the testicle. If the hernia is a sliding type, that is, the wall of the sac is formed by bladder or colon, the sac is closed with a purse-string suture and reduced into the abdomen. Direct sacs do not usually need to be opened; they are usually inverted. In children a herniotomy is all that is required; repair of the posterior wall is not necessary.

Herniorrhaphy

The posterior wall is then repaired. It is strengthened by using sutures or non-absorbable mesh; there are several different types of repair, which are outlined below.

Strangulation of inguinal hernias

The risk of strangulation varies between 0.3 and 2.9 per cent per annum depending on type, and is higher in the first 3 months of the hernia developing. It occurs more commonly with indirect hernias. The patient may present with severe pain in the groin or with symptoms and signs of obstruction.

It is important that the patient be adequately resuscitated before surgery: preoperative blood tests are necessary to determine the degree of dehydration and electrolyte imbalance; abdominal radiographs will indicate if the patient is obstructed; a chest radiograph and electrocardiogram will be required before anaesthesia. Intravenous fluids and a urinary catheter to monitor urine output are essential; a central venous line may also be helpful in ensuring optimum rehydration. Several hours may be required to achieve this. Broad-spectrum antibiotics are necessary to prevent sepsis, and a nasogastric tube to decompress the stomach and small bowel is helpful in decreasing the risk of aspiration.

The principles of surgery are the same as for elective repair except that the contents of the hernial sac need to be inspected and their viability assessed. If bowel resection is required, this can be done safely through the groin. There has been concern about the use of mesh in emergency hernia repairs, but when antibiotic prophylaxis is used there is no increase in infective complications.

Anaesthesia

Groin hernias can be repaired under local, regional, or general anaesthesia. Local anaesthesia is very popular in the United States, where it is used in 70 per cent of hernia repairs, but is less commonly used in the United Kingdom (6 per cent of cases), which is due to surgical conservatism. Local anaesthesia is usually given by a skilled practitioner (surgeon or anaesthetist), either as a regional nerve block or 'infiltrate as you operate' using lignocaine (lidocaine) or bupivacaine. A typical dose regimen is 2 mg/kg body wt of bupivacaine plain or 4 mg/kg with adrenaline (epinephrine), or 3 mg/kg body wt lignocaine plain or 7 mg/kg with adrenaline.

The recommended dose of local anaesthetic should not in general be exceeded. However, the safety margin in the recommended safe dose is wide, as illustrated by serial postoperative plasma concentrations following doses that approach the maximum recommended for lignocaine or bupivacaine. For instance, on administering lignocaine with adrenaline to the maximum dose of 7 mg/kg, peak plasma concentrations ranged from 0.23 to 0.9 mg/l; the threshold for toxicity is 5 mg/l. The administration of 20 ml 0f 0.5 per cent plain bupivacaine resulted in venous plasma concentrations of 0.07 to 1.14 mg/l; cardiovascular toxicity occurs at plasma concentrations greater than 4 mg/l. Thus many surgeons widely exceed the recommended doses without any adverse outcomes. Nevertheless, it is important that patients be closely monitored during surgery as complications due to local anaesthetic agents can occur. An anaesthetist or nurse anaesthetist should be available in the operating room during the procedure. Surgery can be technically more demanding under local anaesthesia and adequate training must be ensured.

The advantages of local anaesthesia are that it has fewer adverse effects on respiratory function than both general and regional anaesthesia, and patients return to normal activities more quickly.

General anaesthesia has improved and short-acting agents such as propofol enable prompt recovery. In the emergency procedures, general anaesthesia is usually required as the repair may be more demanding and bowel resection may be required.

Antibiotics

In emergency hernia repair, antibiotics are mandatory (see above) as there is a greater risk of infective complications postoperatively. In the elective case there has been an increase in the use of prophylactic antibiotics, especially when prosthetic materials are used in the repair, but there is little evidence to support their routine use. The use of antibiotic in the wound or by local infiltration has been found to be of benefit in reducing postoperative wound infections.

Day case

The majority of groin hernias can be repaired as a day-case procedure, which is beneficial in decreased rates of wound infection, earlier return to normal activities, and cost savings. Specialist units in the United States and Europe have shown that the majority of hernias can be repaired on an ambulatory basis. However, the British National Health Service statistics for 1993 show that only approximately 20 per cent of groin hernias were repaired as a day-case procedure.

Patients undergoing hernia repair as a day case must be generally fit, ASA (American Association of Anesthesiologists) grade 1 or 2, and must have adequate social and domestic back-up.

Patients must be assessed before admission for suitability for day-case surgery and will require adequate written instructions on their postoperative care.

Techniques for hernia repair

Sutured

Darns using a non-absorbable suture were once popular in England, but the popularization of the simple and effective Lichtenstein method has eclipsed this obsolete and inferior technique. A darn repair includes plication of the transversalis fascia supplemented by a loose weave of interlocking suture material between the conjoint tendon and the inguinal ligament. Ischaemia induced by the plication and gaps in the weave are probably responsible for the high recurrence rate.

Shouldice repair

In randomized, controlled trials the Shouldice repair has been found to give lower recurrence rates than other suture techniques. Four layers of sutures are required. Traditionally, sutures were made of stainless-steel wire, but polypropylene sutures, which are easier to handle, can be used. This method involves division and resection of the cremaster muscle. After the hernial sac has been dealt with the transversalis fascia just medial to the internal ring is elevated to separate it from the underlying fat. The transversalis fascia is the divided for the whole length of the inguinal canal down to the pubic tubercle. The flaps of the transversalis fascia are lifted up and, using a double-breasting technique, the transversalis fascia is reconstituted. The lower lateral flap is sutured to the deep surface of the upper medial flap, commencing at the medial end of the canal; then the free margin of the upper flap is sutured to the lower flap. A further two layers of sutures are inserted from the deep surface of the conjoint tendon to the upturned edge of the inguinal ligament.

Mesh

Prosthetic mesh has recently become popular for repair of inguinal hernia. The Lichtenstein technique uses a patch of polypropylene mesh approximately 8 × 16 cm, tailored to the individual patient's anatomy. The mesh is trimmed and a slit is made at its lateral edge, creating two tails, an upper and a lower; the upper tail is wider (two-thirds) than the lower (one-third). The mesh is sutured to the inguinal ligament below, and overlaps and is sutured to the conjoint tendon above, using polypropylene. The tails of the mesh are both secured to the inguinal ligament. The mesh has been found to shrink by as much as 20 per cent as the fibrous tissue contracts, so it is important to use a mesh of more than adequate size. This technique has good results and is easy to learn.

Laparoscopic repair

The first laparoscopic hernia repair was performed in 1979, since then this method has been adopted by some enthusiasts. Initial repairs closed off the internal ring with sutures, but due to the high recurrence rates, laparoscopic repairs now use mesh to repair the defect.

There are two main techniques: transabdominal preperitoneal (TAPP) and totally extraperitoneal (TEP). General anaesthesia is required for laparoscopic hernia repair. The transabdominal preperitoneal technique involves insertion of the laparoscope into the peritoneal cavity and dissection of the hernia by elevating the peritoneum behind Hesselbach's triangle. Polypropylene mesh is inserted to repair the hernia; it may be secured with staples or sutures after the repair, and the peritoneum is closed over the operation site to ensure that abdominal contents cannot lie directly in contact with the mesh.

The totally extraperitoneal approach does not involve insertion of the laparoscope into the peritoneal cavity; the dissection in this approach is in the extraperitoneal plane. The plane is developed and carbon dioxide gas is insufflated; several ports are inserted to aid in dissection. Mesh is used to repair the hernia once the sac has been reduced; there is no need to secure the mesh.

This laparoscopic approach has the advantage of fewer wound complications and an earlier return to normal activities. The operation is more expensive, as it initially involves a longer operating time and also often uses disposable equipment. It is technically demanding and has a 'steep learning curve', and for this reason it is mainly undertaken by surgeons with a special interest in laparoscopic surgery.

Outcomes of surgery

Patients should be able to return to normal as soon as resolving pain permits; traditionally, they had been advised to have 6 weeks or even 3 months off work. A randomized, controlled trial of navy recruits showed no difference in recurrence rates when patients were randomized to return to full activities at 3 weeks or at 3 months. The major factors affecting return to activity are motivation and financial incentives. An American study compared two groups of patients and found that in those receiving workers' compensation the duration of postoperative pain was 27 days with return to work at 36.5 days. In those with commercial insurance (self-employed) the duration of postoperative pain was 7.5 days and return to work at 8.5 days.

Patients should not begin driving until 3 to 4 days after surgery as the foot reaction time does not return to normal until then.

Complications of groin hernia repair

Wound complications

Haematoma can be prevented by meticulous haemostasis. Wound infection results in an increased risk of recurrence, and it should be treated swiftly with antibiotics and if necessary opening of the wound.

Seroma occurs more commonly after mesh repair. Large, unresolving, symptomatic seromas can be treated by aspiration under aseptic conditions.

Testicular complications

The incidence of ischaemic orchitis and testicular atrophy is less than 1 per cent after primary repair of inguinal hernia. If previous scrotal or groin surgery has been performed, the risk of testicular damage is greater than 1 per cent. During dissection of the hernial sac from the spermatic cord there is a risk of damage to the testicular artery; however, there is a blood supply to the testicle from the cremasteric vessels and from branches of the internal pudendal artery. It is important that the testicle is not delivered from the scrotum during hernia repair as this will increase the risk of atrophy by disrupting the blood supply to the testicle from arterial anastomoses in the scrotum. Ischaemic orchitis usually presents 4 days after surgery with swelling and pain in the testicle; sometimes it completely resolves but in 25 per cent of cases the testicle gradually atrophies.

Nerve injury

The iliohypogastric, ilioinguinal, and genitofemoral nerves are vulnerable to injury during surgery for inguinal hernia. Division of one of these nerves during surgery, however, will cause little sensory deficit and will prevent this problem. The problem occurs if the nerve is damaged by diathermy or traction. The patient may then develop persistent pain. A local anaesthetic injection can be useful to confirm the neuralgia that has developed, i.e., the sensory nerve that has been affected. If the local anaesthetic was effective, then the nerve can be permanently ablated using phenol, or surgery can be performed to alleviate the symptoms permanently.

Port-site hernias

Small-bowel obstruction occurs in 0.3 per cent of patients after laparoscopic hernia repair, more commonly in the transabdominal approach. Occasionally this is due to a port-site hernia, a complication that can be avoided by adequate closure of the fascial defects created by the ports.

General complications

Visceral injury can occur in open hernia repair as well as during laparoscopic repair. It is important that the contents of the hernial sac be inspected before their reduction into the abdomen. The bladder can be at risk during repair of femoral and direct inguinal hernias; large bowel can be injured in repair of sliding hernias. In laparoscopic hernia repair the viscera can be injured during insertion of the trocars; there have also been several case reports of small-bowel obstruction after transabdominal preperitoneal repair due to adhesion of bowel to the exposed mesh.

Mortality

The mortality after elective inguinal hernia repair is low, but there is still a significant mortality after repair of a strangulated groin hernia when bowel resection is required. The report of the National Confidential Enquiry into Postoperative Deaths in 1991/2 reported the death rate as 7 per cent.

Recurrence

Recurrence after hernia surgery has been defined by Marsden as a weakness of the operation area necessitating a further operation or the provision of a truss (Marsden's definition). Recurrence rates of approximately 10 per cent for primary inguinal hernia repair are reported from United States audit figures. Specialist centres report figures of 1 to 5 per cent. Examination of patients after hernia surgery has found that 50 per cent are unaware of a recurrence. Although most hernias that recur do so within 5 years, recurrences can appear at any time up to 25 years after surgery: 25 per cent of recurrences have arisen at 2 years, 60 per cent by 5 years, and 75 per cent by 10 years.

Femoral hernia

Approximately 5000 femoral hernias are repaired in England in the National Health Service each year; 4 per cent of these are for recurrent hernias. In the United States, 25 000 femoral hernias are repaired annually, which represents 4 per cent of all operations for groin hernia. Femoral hernias are less common than inguinal by a factor of approximately 1 to 25 and are four times more common in women. They are found more often in elderly and multiparous individuals, but can present in the nulliparous woman or rarely in childhood.

Anatomy 

Femoral hernias emerge through the groin from the femoral canal, which has rigid boundaries consisting of medially the lacunar ligament, anteriorly the inguinal ligament, posteriorly the pectineal ligament, and laterally the femoral vein. The femoral canal normally contains lymph nodes and loose connective tissue, which forms the characteristic 'onion skin' over the fundus of the hernia sac.

Presentation and diagnosis

A femoral hernia may be an incidental finding or it may present as a symptomatic groin swelling. A relatively large proportion (30–80 per cent) present with strangulation and/or obstruction due to the narrow neck of the hernial sac and the sharp edge of the lacunar ligament.

Differential diagnosis

Lymph nodes, lipoma, inguinal hernia, aneurysm of the femoral artery, saphena varix, and varicocele (occasionally seen in preg-nancy).

Treatment

Surgery is mandatory once the diagnosis of femoral hernia has been confirmed. Ideally, the operation should be within a month of diagnosis and patients must be warned to present to hospital immediately if they have any signs of obstruction or strangulation. If the diagnosis of femoral hernia is in doubt, surgical exploration should be performed.

Emergency treatment

Strangulated hernias are treated surgically, but resuscitation is very important and the patients must be adequately rehydrated and receive prophylactic antibiotics before surgery. Although urgent surgery is required, several hours may be necessary to ensure the patient is optimally resuscitated.

Surgery

The principle is the same in all of the three main approaches to femoral hernia repair: dissection of the sac, inspection of the contents, ligation of the sac, and hernia repair, usually with sutures to approximate the inguinal and pectineal ligaments.

The low approach (Lockwood)

This method has been advocated for elective repair when the contents of the sac are viable; it is simple and easy.

After preparing the patient for surgery a transverse or skin-crease incision is made over the lump and the sac is dissected out from the several layers of connective tissue that may surround it. The sac is opened and the contents inspected. If viable the contents are reduced; if non-viable omentum is present it is excised. If the sac contains non-viable bowel, it is best to proceed to a lower midline incision in order to perform a bowel resection. It can often be difficult to reduce the contents of the sac and it may be necessary to make an incision in the lacunar ligament to release its neck. (An abnormal obturator artery is present in 20 per cent of cases: usually it lies on the lateral side of the femoral canal; rarely it lies medially close to the lacunar ligament; and occasionally this can lead to troublesome bleeding when the lacunar ligament is divided.) The sac can then be ligated and excised.

The repair is then made with a non-absorbable suture to approximate the inguinal ligament to the pectineal ligament, taking care to protect the femoral vein, which lies laterally.

Transinguinal (Lotheissen)

This technique involves a standard oblique groin incision above and parallel to the inguinal ligament, followed by incision of the external oblique and opening of the inguinal canal. The femoral hernia is approached by opening the transversalis fascia at the back wall of the canal. The hernial sac is then reduced and the repair done as described above. This technique is less popular as it is thought to weaken the inguinal canal.

High approach (McEvedy)

This approach is generally considered the optimum method for strangulated femoral hernias. Classically an oblique or paramedian skin incision is made. However, an acceptable modification is the use of a unilateral Pfannenstiel incision, which can be extended across the midline if a laparotomy becomes necessary. The rectus sheath is then opened longitudinally and the rectus muscle retracted medially. The transversalis fascia can then be pushed away from the inguinal ligament to expose the femoral canal. If the sac is empty it can be withdrawn into the abdomen and the hernia repaired from above by approximation of the inguinal and pectineal ligament using non-absorbable sutures. If the hernia sac cannot be reduced, the peritoneum is opened and by gentle traction from above the contents are withdrawn from the sac. If there are still difficulties, the use of pressure from below and division of the lacunar ligament should enable this manoeuvre to be completed. If the contents are not viable a resection can be performed through the same incision. The hernia can then be repaired and the peritoneum closed, and then the rectus sheath repaired.

A similar type of repair can be performed in a preperitoneal approach using a lower midline incision.

Laparoscopic repair

Femoral hernias can be repaired laparoscopically either by a transabdominal or extraperitoneal approach. However, the laparoscopic operation requires extensive dissection and has to be done under general anaesthesia, the equipment required is more expensive, and at present there is no evidence to suggest that it is more efficacious than the open repair.

Plug repair

Plugs of mesh can be inserted into the femoral canal to repair the hernia. This has been found to give low rates of recurrence, but migration of the mesh and infections, which are thought to occur more commonly when mesh is rolled up, have been described.

Which repair?

The traditional teaching has been that the low approach should be used for elective repair and the McEvedy should be performed for emergency hernia repair. Systematic review of the literature has shown little evidence to support this and it is quite acceptable to use any of the approaches. However, the transinguinal approach may result in a higher recurrence rate.

Further reading

Cheek CM, Black NM, Devlin HB, Kingsnorth AN, Taylor RS, Watkins D. Systematic review on groin hernia surgery. Annals of the Royal College of Surgeons of England 1998; 80 (Suppl. 1). [A meta-analysis of 4977 citations from the hernia literature, providing evidence-based best practice.] 

Devlin HB, Kingsnorth AN. Management of abdominal hernias, 2nd edn. Chapman and Hall, London, 1998.[The definitive English language text.]

Royal College of Surgeons of England. Guidelines on the management of groin hernia in adults. RCS, London, 1992. [Practical care pathways from diagnosis to operation and postoperative care.]