Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice (18 page)
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Authors: Simon Paterson-Brown MBBS MPhil MS FRCS
Anatomy
The anatomy of the inguinal region is complex. The inguinal canal is approximately 4 cm in length and is located just above the inguinal ligament between the internal and external rings. The inguinal canal allows passage of the spermatic cord into the scrotum, along with the testicular, deferential and cremasteric vessels. The superficial ring is a triangular aperture in the aponeurosis of the external oblique and lies about 1 cm above the pubic tubercle. The ring is bounded by a superomedial and an inferolateral crus joined by criss-cross intercrural fibres. Normally, the ring will not admit the tip of the little finger. The deep ring is a U-shaped condensation of the transversalis fascia and it lies about 1 cm above the inguinal ligament, midway between the pubic tubercle 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.
The anterior boundary of the inguinal canal comprises mainly the external oblique aponeurosis with the conjoined muscle laterally. The posterior boundary is formed by the fascia transversalis and the conjoined tendon (internal oblique and transversus abdominus medially). The inferior epigastric vessels lie posteriorly and medially to the deep inguinal ring. The superior boundary is formed by the conjoined muscles (internal oblique and transversus) and the inferior boundary by the inguinal ligament.
An indirect hernia travels down the canal on the outer (lateral and anterior) side of the spermatic cord. A direct inguinal hernia comes out directly forwards through the posterior wall of the inguinal canal. While the neck of an indirect hernia is lateral to the epigastric vessels, the direct hernia usually emerges medial to these vessels, except in the saddle-bag or pantaloon type, which has both a lateral and a medial component (
Fig. 4.4
).
Figure 4.4
Laparoscopic totally extraperitoneal (TEP) view of the right groin with a direct inguinal hernia (DH) lying medial to the inferior epigastric vessels (IE), above the inguinal (IL) and lacunar (LC) ligaments. The pubic bone (P), iliac vessels (IV), vas and vessels (VV) are also seen. The positions of a femoral hernia (FH) and indirect inguinal hernia (IH) are also marked.
Chapter 12
)
Repair of congenital inguinal hernia is the most frequently performed operation in the paediatric age group. Although inguinal hernias can present at any age, the peak incidence is during infancy and childhood. About 3–5% of full-term infants may be born with a clinical inguinal hernia. Between 80% and 90% of paediatric hernias occur in boys, about one-third of the hernias presenting in the first 6 months of life. Congenital inguinal hernias have a 15% bilateral presentation.
Examination of the inguinal area for a hernia may show an obvious bulge at the site of the external ring or within the scrotum that can often be gently reduced. However, the bulge may only be seen during severe straining, such as with crying or defecation. If the infant is old enough to stand, he or she should be examined in both the supine and standing positions. If not, the parent can hold the infant upright so that the surgeon can closely observe the inguinoscrotal area. Sometimes, photographs taken by the parent when a swelling appears can aid in the diagnosis in the difficult case. It is essential to make sure that the testis is within the scrotal sac to avoid mistaking a retractile testis for a hernial bulge. The presence of an empty scrotum should alert the examining surgeon to a possible undescended or ectopic testis, which is associated with an inguinal hernia in more than 90% of patients. Although routine orchidopexy is usually delayed until the child is 1 year of age, a coexisting symptomatic hernia should be promptly repaired and orchidopexy accomplished at the same time.
Inguinal hernias in infants and children are prone to incarcerate, with the overall rate being 12%.
13
Incarceration is most common in the first 6 months of life, when more than half of all instances are observed. An incarcerated hernia usually presents as an acute tender mass in the inguinal canal. The mass may protrude beyond the external inguinal ring or into the scrotum. The skin over the mass may be discoloured, oedematous, erythematous or blue. Strangulation, characterised by abdominal distension, vomiting, failure to pass faecal material, tachycardia and radiological evidence of small-bowel obstruction, demands emergency operative intervention for relief of obstruction, intestinal salvage and hernia repair. In contrast to the adult with an incarcerated hernia, in children testicular ischaemia is far more common than intestinal ischaemia, and it is therefore appropriate to be aggressive about reducing the hernia (see
Chapter 12
).
In general, hernias in children and particularly infants should be managed by experienced paediatric surgeons (see also
Chapter 12
). However, this is not always possible depending on geography and availability. In these circumstances the general surgeon on call may be required to manage these patients. As most (80%) incarcerated hernias in children may be managed initially by non-operative measures, which include sedation, and then gentle reduction when the baby is quiet, exploration may be safely delayed for about 24–48 hours, allowing, if possible, a more experienced paediatric surgeon to become involved. However, if the hernia remains irreducible at this stage, emergency repair is indicated. The complication rate is approximately 20 times greater after emergency repair for incarcerated hernia than after elective procedures.
14
It is therefore worthwhile to reduce the hernia whenever possible and perform an elective procedure within 24–48 hours of the reduction. The high risk of incarceration in the paediatric age group makes the presence of an inguinal hernia an indication for surgical repair.
Operative details:
Surgical access is achieved through a short (2–3 cm) transverse incision in the lowest inguinal skin crease. The superficial fascia (Scarpa's fascia) is incised and the external oblique fascia identified. The aponeurosis is traced laterally to identify the inguinal ligament and the exact location of the external inguinal ring identified. Although some surgeons advocate repair through the external ring (Mitchell Banks technique
15
), an alternative approach is to incise the external oblique fascia in the long axis of its fibres, perpendicular to the external inguinal ring. This exposes the cremasteric muscle and fascia, which envelop the cord structures.
The hernial sac is always located in an anteromedial position in relation to the cord and gentle blunt dissection of the cremasteric fibres usually brings the sac into view. The sac is elevated with a haemostat and the cremasteric fibres carefully freed from the anterior and lateral aspects. Retraction of the sac medially allows identification of the spermatic vessels and vas deferens, and these structures may be carefully teased away from the sac in a posterolateral direction. Injection of 1–2 mL of saline into the cord may help to define the planes of separation. The vas itself should not be grasped and the floor of the canal not disturbed. Once the end of the sac has been freed, the dissection of the sac is carried superiorly to the level of the deep inguinal ring. If the sac extends down into the scrotum, it may be divided once the cord structures are identified and protected. The base of the sac may then be gently twisted to reduce any fluid or viscera into the peritoneal cavity. The base of the sac should be suture ligated with an absorbable suture and, once the suture is cut, the peritoneal stump should retract proximally through the deep inguinal ring. Free ties should not be used because of the risk of them becoming dislodged if abdominal distension occurs. Absolute haemostasis is essential to prevent postoperative haematoma formation. The position of the testis within the scrotum should be confirmed to avoid iatrogenic entrapment within the inguinal canal. There is an increasing role for laparoscopic hernia repair in infants and young children.
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An emergency operation is required for patients with an incarcerated hernia, with toxicity and obvious intestinal obstruction or after failed attempts at reduction. As previously mentioned, a paediatric surgeon should be involved in all cases if possible as this can be a difficult undertaking. After appropriate resuscitation, prophylactic antibiotics and insertion of a nasogastric tube, the operation begins with preparation of the whole abdomen in case laparotomy is required. An inguinal incision is utilised and the incarcerated intestine carefully inspected for viability once the obstruction at the internal ring is relieved. A rapid return of pink colour, sheen, peristalsis and palpable or visible pulsations at the mesenteric border should be observed. If there is any question regarding intestinal viability, resection and anastomosis should be carried out and hernial repair accomplished.
In certain circumstances, the incarcerated intestine may reduce during surgical manipulation, before the intestine has been visualised. However, such spontaneous reduction of infarcted bowel is very rare. Laparoscopy through the hernial sac can be undertaken if there are serious concerns regarding bowel viability. Surgery for incarcerated hernia may be difficult because of oedema, tissue friability and the presence of the mass, which may obscure the anatomy. The gonad should be carefully inspected because it may become infarcted by vascular compression caused by the incarcerated intestine. The undescended testis is more vulnerable to this complication in the presence of incarcerated intestine.
Complications may be divided into intraoperative and postoperative categories. Intraoperative complications include: division of the ilioinguinal nerve, which can be avoided if the external oblique fascia is elevated before incision; division of the vas deferens, which should be repaired with interrupted 7–0 monofilament sutures; and bleeding, which is usually secondary to needle-hole injury and can usually be controlled with withdrawal of the suture and the application of pressure.
Postoperative complications include wound infection, scrotal haematoma, postoperative hydroceles and recurrence. The wound infection rate is low (1–2%) and recurrence rates of less than 1% are reported, 80% of recurrences being noted within the first postoperative year. The major causes of recurrence in infants and children include: (i) a missed hernial sac or an unrecognised tear in the peritoneum; (ii) a broken suture ligature at the neck of the sac; (iii) injury to the floor of the inguinal canal, resulting in the development of a direct inguinal hernia; (iv) severe infection in the inguinal canal; and (v) increased intra-abdominal pressure, as is noted in patients with ascites after ventriculoperitoneal shunts, in children with cystic fibrosis, after previous operation for incarceration and in patients with connective tissue disorders. Although failure to repair a large internal inguinal ring is a possible (and very occasional) cause of recurrence, attempts to tighten the internal ring at the time of the first repair by approximating the transversalis fascia medial to the inferior epigastric vessels risk compromising the blood supply to the testicle and should be avoided where possible. Simple excision of the sac is all that is required in most patients. Re-operations for recurrent inguinal hernia may be a technical challenge and a pre-peritoneal approach is an extremely useful alternative for recurrent hernias.
Inguinal hernias are more frequent in males, with a male to female ratio of 12:1. The peak incidence is in the sixth decade and 65% are indirect in type. Right-sided inguinal hernias are slightly more common than left-sided, 55% occurring on the right. Bilateral hernias are four times more common in direct than indirect forms.
The pathogenesis of groin hernias is multifactorial. It was initially believed that persistence of a patent processus vaginalis into adult life was the predisposing factor for indirect inguinal hernia formation. However, post-mortem studies have shown that 15–30% of adult males without a clinically apparent inguinal hernia have a patent processus vaginalis.
16
Similarly, review of the contralateral side in infantile inguinal hernias reveals a patent processus vaginalis in 60% of neonates and a contralateral hernia in 10–20%. During 20 years of follow-up after infantile hernia repair, only 22% of men will develop a contralateral hernia.
It is therefore apparent that the problem of indirect inguinal hernia is not simply one of a congenital defect. The high frequency of indirect inguinal hernia in middle-aged and older people suggests a pathological change in connective tissue of the abdominal wall to be a contributory factor,
1
as discussed earlier.
The essential goal of hernia repair is to restore the functional integrity of the laminar musculo-aponeurotic structure of the groin region and the musculo-aponeurotic fenestration, which allows the vessels to the genitalia to penetrate this structure. It is beyond the scope of this chapter to review the history of the various repair techniques that have been previously employed and are now mainly historical. However,
Fig. 4.5
illustrates how the popularity of suture and mesh techniques has changed in the Lothian region of Scotland in the last 20 years. Only the latest techniques (i.e. prosthetic repairs) will be considered here.
Figure 4.5
Changing patterns in suture, mesh and laparoscopic inguinal hernia repair in the Lothian Region, Scotland.
Tension-free prosthetic mesh repair:
Lichtenstein first described the technique of tension free repair of groin hernia, which now bears his name.
17
Tension-free repair of primary groin hernias may be performed as an outpatient procedure under local anaesthesia, although in the UK open mesh repair is still more commonly performed under general anaesthetic.
Once the local anaesthesia has been administered (typically a mixture of 0.5% bupivacaine and 1% lignocaine) along the line of the proposed incision, a cut is made in the groin-crease and a window established through the subcutaneous tissues including Scarpa's fascia at the lateral end of the wound, exposing the external oblique aponeurosis. The window is increased in size to expose the medial end of the external oblique aponeurosis, the inguinal ligament and the superficial ring. Additional anaesthetic is then injected under the external oblique aponeurosis, following which a small incision is made in the external oblique along the line of the fibres, approximately 2 cm above the inguinal ligament. The edges are carefully lifted with haemostatic forceps to avoid damage to the ilioinguinal nerve. The external oblique aponeurosis is then opened along a line from the incision to the superficial ring and the contents of the inguinal canal gently separated from it. After a self-retaining retractor has been inserted under the edges of the external oblique aponeurosis, the spermatic cord is mobilised utilising the avascular space between the pubic tubercle and the cord itself to avoid damage to the floor of the canal, injury to the testicular blood flow and crushing of the genital nerve, which always lies in juxtaposition to the external spermatic vessels (
Fig. 4.6
).
Figure 4.6
Open right inguinal hernia repair. External oblique has been opened. Medial is to the right of the picture with superior at the top. Note the iliohypogastric (IH), ilioinguinal (II) that splits into two branches, and the small genitor-femoral nerve (GF) lying inferiorly.
Clinical photograph used with permission of Mr Martin Kurzer, London, UK.
In order to thin out the spermatic cord and remove any lipoma present, the cremaster fibres are incised longitudinally at the level of the deep ring. Complete excision of the cremaster fibres from the spermatic cord is unnecessary and may result in damage to the vas deferens, increasing the likelihood of postoperative neuralgia and ischaemic orchitis. Indirect hernial sacs are opened and digital exploration performed to detect any other defects or the presence of a femoral hernia. Lichtenstein states that the sac may be simply inverted into the abdomen without excision, suture or ligation, which he feels is unnecessary and may contribute to postoperative discomfort.
17
However, it is the author's practice to suture ligate any but the smallest hernial sacs at the level of the deep ring and excise any redundant peritoneum. To prevent postoperative hydrocele formation, complete scrotal sacs are transected at the midpoint of the canal, with the distal section left open and in situ. If performing the procedure under local anaesthetic, handling of the sac at this stage can cause pain and often further local anaesthetic to the sac area in the region of the deep ring is required.
In the event of a large direct hernia, the sac (transversalis fascia) is invaginated with an imbricating suture to achieve a flat surface over which to lay the prosthetic mesh. The external oblique aponeurosis is separated from the underlying internal oblique muscle at a point high enough to accommodate a mesh measuring around 11 cm × 6 cm. This size will vary depending on the size of the patient and the size of the hernial defect.
The mesh is trimmed as appropriate so that the patch overlaps the internal oblique muscle and aponeurosis by at least 2 cm above the border of the Hesselbach triangle. The medial portion of the mesh is rounded to the shape of the medial corner of the inguinal canal. The mesh is sutured to the aponeurotic tissue over the pubic bone, overlapping the bone to prevent any tension or weakness at this critical point, but ensuring the periosteum is not caught in the suture as this is believed to be a good source of chronic pain. The medial part of the mesh should extend at least 2 cm medial to the pubic tubercle to reduce the risk of medial recurrence. The same suture is continued along the lower edge, attaching the mesh to the shelving portion of the inguinal ligament to a point just lateral to the deep ring with a continuous suture.
A slit is made at the lateral end of the mesh, creating a wider tail above the cord and a narrower one below the cord. This manoeuvre positions the cord between the two tails of the mesh and avoids the keyhole opening, which is less effective at preventing recurrence. The upper edge of the patch is sutured to the internal oblique aponeurosis using a few interrupted sutures or widely spaced continuous suture. Sharp retraction of the upper leaf of the external oblique aponeurosis from the internal oblique muscle is important because it provides the appropriate amount of laxity for the patch. When the retraction is released, a true tension-free repair is taken up when the patient strains on command during the operation (if under local anaesthetic) or resumes an upright position afterwards. Using a single non-absorbable monofilament suture, the lower edges of the two tails are fixed to the shelving margin of the inguinal ligament just lateral to the completion knot of the lower continuous suture. This creates a new deep ring of mesh (
Fig. 4.7
). Some surgeons simply suture the lower edge of the upper tail to the upper edge of the lower tail.
Figure 4.7
Left inguinal hernia repair. Mesh in place. Note continuous suture attaching inferior edge of mesh to inguinal ligament and mesh fish-tailed laterally to create a new deep ring. Cord structures and ilioinguinal nerve are intact. The mesh is lying flat and ‘tension’ free.
The excess patch is trimmed on the lateral side, leaving 3–4 cm beyond the deep ring. This is tucked underneath the external oblique aponeurosis and the external oblique aponeurosis closed with a continuous suture. Unrestricted activity is encouraged and patients are expected to return to their normal activity 2–7 days after surgery.
In the past few years, there has been an explosion in different mesh types for the open repair of inguinal hernias. The plug and patch utilises a cone-shaped mass of mesh that can be inserted, tip side inwards, into either the deep or superficial rings, depending on the type of hernia. A flat mesh is then placed over the plug akin to the Lichtenstein technique. The prolene hernia system is two flat meshes secured together by a small cyclinder of mesh. The aim is to insert one mesh into the pre-peritoneal space and the other is secured akin to the Lichtenstein technique. There is also the open pre-peritonel approach with the Kugel patch, for example. All these alternatives report good results in the hands of experts, but the open flat mesh technique in its various forms, akin to the Lichtenstein technique, remains the commonest technique in Western countries to date. It is also the author's prejudice that if a mesh is to be inserted into the pre-peritoneal space, it makes sense to do this under direct vision using a laparoscope rather than using a largely blind, blunt finger dissection technique.
Laparoscopic repair:
The alternative to an open operation is a laparoscopic approach. Ger is credited with the first laparoscopic approach to hernia, repairing indirect hernias with a stapling instrument developed for this purpose.
18,
19
In parallel, Gazayerli described a suture repair technique through a transabdominal approach, approximating the transversus abdominis aponeurotic arch and the iliopubic tract.
20
After the repair is completed, the peritoneum is re-approximated. Since the early 1990s, laparoscopic hernia repair has evolved from simple closure of a small indirect hernia, through the placement of mesh plugs and a small mesh patch over the internal ring, to the current use of large pieces of prosthetic mesh to reinforce the lower abdominal wall.
The rationale for the use of large mesh sheets placed into the pre-peritoneal space was based on the surgical experience of the open pre-peritoneal hernia repair, especially in the treatment of recurrent hernias.
21
Although a variety of laparoscopic repairs have been described, they can be categorised in general according to the approach used to expose the defect. Three exposures are used: the intraperitoneal approach, in which the prosthesis is placed as an onlay graft over the peritoneum; the transabdominal pre-peritoneal (TAPP) repair; and the totally extraperitoneal (TEP) repair.
Intraperitoneal prosthetic repair:
In the intraperitoneal repair with an onlay graft, the prosthesis is placed within the peritoneal cavity. The technique is well described by Toy and Smoot.
22
Compared to the TAPP and TEP approaches, it has the advantages of being less time-consuming to perform and requires no dissection of the pre-peritoneal space. It has the disadvantage of leaving the prosthetic material exposed within the peritoneal cavity and has a higher recurrence rate. It is the author's view that this operation is very much an operation of last resort, when other open or laparoscopic techniques have failed. It is possible that when better non-stick meshes become available, combined with glue fixation, this technique may gain in popularity.
Transabdominal pre-peritoneal prosthetic repair:
TAPP repair is one of the most popular approaches used for laparoscopic herniorrhaphy, particularly in Europe. The abdomen is insufflated with carbon dioxide and the laparoscope introduced through an umbilical incision. Two accessory trocars, placed well above and slightly medial to the anterior superior iliac spines, are used to provide access for the dissecting instruments and the stapler. After both groins have been inspected, a second incision is made in the pelvic peritoneum several centimetres above the hernia defect, typically in line with the level of the anterior iliac spine, and the peritoneum then peeled away to expose the hernia defect. The peritoneum is dissected bluntly away from the abdominal wall, allowing the hernia sac to be inverted and dissected free of adherent tissue. Pre-peritoneal fat is removed to allow identification of the transversus abdominis arch, the pubic tubercle, the iliopubic tract and Cooper's ligament. A prosthetic mesh of approximately 10 cm × 15 cm is inserted and manipulated into position so that it covers the entire myopectineal orifice. Some surgeons fix the mesh in place with staples, sutures or glue, although there is little evidence to support such practices. The peritoneum is closed over the mesh with staples or sutures. This approach has the advantage of permitting inspection of the abdomen in general, and of the opposite side in particular, enabling bilateral repairs to be performed if necessary. In addition, exposure is usually excellent. The disadvantage is that a wider dissection is required to accommodate the mesh than is used in the intraperitoneal onlay procedure. In addition, the intra-abdominal incision presents the possibility of injury to intraperitoneal structures and a second peritoneal incision in the groin increases the potential for adhesion formation and late bowel obstruction.
Totally extraperitoneal prosthetic repair:
TEP repair is a laparoscopic adaptation of the open posterior pre-peritoneal approach first described by Annandale.
23
The laparoscope is introduced into the pre-peritoneal space through an infra-umbilical incision. The pre-peritoneal space is dissected towards the symphysis pubis, Cooper's ligament and the iliac vessels with a blunt instrument or space-making balloon. Carbon dioxide is insufflated into the pre-peritoneal space to maintain exposure. Care must be taken to avoid entering the peritoneum; if this occurs, loss of pressure in the pre-peritoneal space can result, making exposure more difficult. A venting Verres needle in the right iliac fossa will usually resolve this problem, or alternatively a structural balloon attached to the umbilical port will help to keep the pre-peritoneal space open. Two additional 5-mm ports are inserted, either in the right and left iliac fossa, after extending the dissection laterally or in the midline below the umbilicus. Direct hernial sacs usually reduce with ease, but an indirect hernial sac may need more work. The key landmark here is the vas. The indirect hernial sac lies above and lateral to the vas, taking the dissection away from the iliac vessels, preventing their inadvertent injury. A mesh of minimum size 10 cm × 15 cm is used to cover all the inguinal and femoral myopectineal orifices, ensuring good cover laterally and superiomedially. As with TAPP repairs, there is now good evidence that suturing, tacking or stapling of mesh does not reduce the risk of hernia recurrence but is a cause of postoperative chronic pain.
24
The author does occasionally tack the mesh, confined mainly to the patient with a very large direct hernial defect or when there has been more bleeding than usual, especially patients on aspirin. In all circumstances tacks are placed medial to the inferior epigastric vessels and superior to the pubic bone only. More recently, the author has attempted laparoscopic suture closure of large direct inguinal hernias with a non-absorbable suture rather than using tacks. The TEP approach avoids the risks of entering the peritoneal cavity and subsequent intraperitoneal adhesion formation.
There is little evidence to support TEP versus TAPP and the technique used is largely down to the individual surgeon. The author's preference is the TEP approach, with the TAPP approach reserved for recurrence after a previous TEP or open intraperitoneal operations.
Laparoscopic repair of ingiunal hernias causes less acute and chronic pain, thus earlier return to work, less infection, fewer wound complications and less numbness than the open operation. It is currently the preferred technique recommended by the National Institute for Clinical Excellence (NICE) for recurrent inguinal hernias and bilateral primary inguinal hernias, and an alternative operation for primary unilateral hernias.
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