Inguinal hernia repair
I. M. C. MACINTYRE
Western General Hospital, Edinburgh, Scotland, U.K.
J.R.Coll.Surg.Edinb., 46, December 2001 349-353 

Inguinal hernia repair has been evolving for the past 130 years and the pace of evolution accelerated in the last decade with the introduction of the tension-free repair, the laparoscopic repair and the growth of the specialist hernia clinic. The evolution continues and this article sets out to describe the author’s approach at the time of writing.

Keywords: inguinal hernia repair, herniotomy, mesh repair, laparoscopic total extraperitoneal (TEP) technique, post-operative care

INTRODUCTION

Inguinal hernia repair has been evolving for the past 130 years - since the pioneering days of Marcy, Annandale and Bassini. The pace of evolution accelerated in the last decade with the introduction of the tension-free repair, the laparo-scopic repair and the growth of the specialist hernia clinic. The evolution continues and this article sets out to describe the author’s approach at the time of writing.

PRE-OPERATIVE PREPARATION

A detailed account of patient selection and preoperative preparation is beyond the scope of this article. Patient selection is usually straightforward. Where the inguinal hernia is indirect or where it is not possible to exclude an indirect hernia, surgical repair should be offered unless there is a contra-indication. The one group of patients in whom surgery should not be routinely recommended are elderly men with small and obviously direct hernias which are not causing symptoms.

Every patient should be considered for day surgery. In some cases, this will not be possible by reason of age, frailty, distance, inappropriate home circumstances or co-morbidity. To this end, assessment at a pre-admission clinic is highly desirable, if not essential. In such a setting, these various factors can be assessed in full, the patient can be given a detailed explanation, which should be accompanied by a booklet outlining the preoperative and postoperative course and setting out postoperative instructions.

Choice of Prosthetic Material

Present evidence points to mesh repair as the procedure of choice for adult hernias. In children, herniotomy alone is the operation of choice. The choice between herniotomy alone and mesh repair enters a grey area in the late teens and early twenties but, over the age of 25, I believe all such hernias should be repaired using a mesh.

The Lichtenstein repair is currently the most appropriate operation for primary inguinal hernias. It is associated with excellent outcome in the hands of non-specialist surgeons and results in less postoperative pain, earlier return to normal activities and a lower recurrence rate, when compared with sutured repairs. For bilateral hernias, on the other hand, a laparoscopic total extraperitoneal (TEP) technique remains my choice. It is associated with less pain and an earlier return to normal activities for the patient than a bilateral Lichtenstein technique. Similarly, the TEP procedure is my choice for recurrent hernia. The surgeon is almost always dealing with virgin tissue planes and the procedure is no more difficult than for a primary procedure. Using an open technique to deal with a recurrence after a previous mesh procedure can be particularly difficult.

Choice of Operation

The factors which influence this choice are firstly, pore size. The mesh should not contain pores of less than 10um in diameter as these may harbour bacteria making them inaccessible to leukocytes. Conversely, the mesh should contain pores of larger than 90um, in order to promote the most rapid ingrowth of blood vessels and fibroblasts and the optimal laying down of collagen. Polypropylene is the most widely used material and, of the brands available, both Marlex (C.R. Bard Inc., Burlington, USA) and Prolene (Ethicon Ltd, Edinburgh, UK) are monofilament meshes. Surgipro (Tyco, U.S.S.C. Norwalk, Ct., USA) is multifilament mesh, with a pore size of less than 90um, although a monofilament version is now available. Mersilene (Laboratoires Bruneau, Boulogne, France) is a multifilament knitted polyester mesh, which, because of small pore size, carries the theoretical increased risk of infection. Its principal advantage is “lack of memory”, which is a considerable advantage when repairing large ventral hernias. For inguinal hernias, for both the open and laparoscopic procedures, I find Prolene fulfills the theoretical criteria and is easy to handle.

Operative technique for open mesh repair of inguinal hernia

Preparation Prior to Repair

When these are repaired under local anaesthetic begin by checking the side to be repaired with the patient and the indelible mark placed pre-operatively. All patients should have an intravenous cannula inserted. Some patients will benefit from a small dose of midazolam and/or pethidine during the procedure. Ensure that the patient’s upper limbs are held in such a way that they cannot be pushed into the operative field if the patient dozes off and inadvertently pushes his hands toward the operative field. A pulse oximeter, an automated blood pressure cuff and ECG electrodes should be placed before the start of the operation. An appropriately qualified nurse (in the absence of an anaesthetist) should be at the head of the table to monitor pulse, blood pressure, oxygen and oxygen saturation and to speak to the patient, as required. The operating table is tilted head down by about 15^o.

Local Anaesthetic Technique

The use of a combination of lignocaine and bupivacaine has become popular as it combines the rapidity of onset of the former with the long acting effect of the latter. I use 30 ml of 1% lignocaine with adrenaline which contains 100 mg of lignocaine. The maximum recommended dose for a 70 kg man is 490 mg. In addition, 30 mg of 0.25% bupivacaine with adrenaline is used, a total of 75mg. The maximum recommended dose for a 70 kg man is 280mg ( 4mg/kg).

I begin by infiltration of the skin using lignocaine. A sub-cutaneous weal is raised 1cm medial to the anterior superior iliac spine. A further subcutaneous weal is raised two fingers breadth in from this and through this a 23 gauge spinal needle is inserted sub-cutaneously and, with the obturator withdrawn, 10-15ml of lignocaine solution is inserted as a subcutaneous weal along the line of the incision. A second subcutaneous weal is raised just above the pubic tubercle and a further 5ml of lignocaine is injected here in a fan extending upwards and laterally from the pubic tubercle. This leaves 10ml of lignocaine solution for use during the procedure. An ilio-inguinal block is then performed using bupivacaine. Begin by inserting a beveled needle through the skin weal in front of the anterior superior spine, passing the tip through the external oblique aponeurosis, and injecting 10mls of bupivacaine in a fan shape. A 21 gauge spinal needle is then inserted deep to the external oblique aponeurosis and a further 10mls Of bupivacaine injected here. This leaves 10ml of bupivacaine to splash into the inguinal canal and wound before closure.

The lignocaine is used during the procedure to inject two areas: firstly the pubic tubercle and surrounding tissues and, secondly, the peritoneum forming the base of the indirect sac. Lignocaine is best here as it gives a more immediate response. The remaining lignocaine is used during the procedure should further immediate anaesthesia be required.

Skin Incision

The skin incision is placed 1cm. above and parallel to the inguinal ligament. It should extend from the pubic tubercle medially to about 1cm lateral to the deep ring. Like many surgeons, I had a brief flirtation with skin crease incisions but found that this approach could make medial access more difficult and the alleged cosmetic improvement offered by this incision was barely discernible. Dissection is deepened into the subcutaneous fat where two veins, the superficial epigastric and the superficial external pudendal should be divided between ligatures whilst smaller vessels can be diathermied. The external oblique aponeurosis is identified now and exposed along the length of the incision (Figure 1).

All figures show a left inguinal hernia repair

Figure 1 Showing external oblique oponeurosis

I used to dissect this layer down to the inguinal ligament and release the fascia lata just below the ligament but I now think that dissection superficial to the external oblique aponeurosis should be kept to a minimum. The inguinal canal is opened along the line of the fibres of the external oblique aponeurosis extending the incision into the superficial ring. An incision, 2cm above the inguinal ligament, provides a large lower leaf for optimal closure (Figure 2).

Figure 2 Dividing the external oblique oponeurosis

A gentle sweep with the finger under the external oblique aponeurosis opens this plane widely for the later insertion of the mesh. At this stage I like to make a formal incision into the cremasteric fascia for the full length of the cord. If an indirect sac is present, it is now dissected free from the cord structures which are safeguarded and retracted (Figure 3).

Figure 3 Important structures in the dissection of the sac (for clarity the fascial coverings of cord structures are not shown in this diagram)

I then decide whether the cremasteric pedicle is to be ligated and divided. It is usually necessary to do this but, if it can be preserved without interfering with the insertion of the mesh, then I preserve it. One important consideration here is the genital branch of the genito-femoral nerve, which accompanies the cremasteric vessels through the canal (Figure 3). If the cremasteric pedicle is to be divided then the genito-femoral nerve should be separated from it and cut cleanly without ligation. The cord at this stage should be safeguarded and retracted on a tape. An indirect sac should be dissected free with sharp dissection after identifying the fundus (Figure 3). In an obese patient the sac may not be immediately obvious but it should lie above and in front of the cord structures. In a large indirect hernia, where the sac extends beyond the inguinal canal, it should not be dissected beyond the external ring, but divided at that level leaving the distal part of the sac undisturbed. The Lichtenstein group recommends that an indirect sac should not be routinely opened to ensure that it is empty, but merely invaginated. There is general agreement that a direct sac should not be opened. If the sac is bulky a continuous, plicating, absorbable suture to tack this down may make it easier to seat the mesh but I try to avoid this type of suture as I find it can contribute to post operative discomfort.

Inserting and Fixing the Mesh

Before the mesh is inserted I ensure that the plane between the external oblique and conjoint tendon is opened up as widely as possible. Inferiorly, the full length of the inguinal ligament should be exposed; medially, it should extend up to the mid-line and superiorly, up to the fusion between the two layers.

A 15 x 10cm Prolene mesh should now be trimmed to fit this space, with a slit cut laterally to accommodate the spermatic cord. The mesh should lie with the medial edge 1-2cm medial to the pubic tubercle.

After moving the mesh- with further trimming if necessary-until it lies in the ideal position, it should be fixed inferiorly first starting at the medial end (Figure 4).

Figure 4 Moving the mesh and fixing inferiorly

I use a continuous 2/0 Prolene taking the first bite into mid-line aponeurotic tissue and continuing laterally, taking aponeurosis or areolar tissue but not pubic periosteum. As it proceeds laterally, the continuous suture takes the internal surface of the inguinal ligament and continues laterally as far as the incision will allow. Where the cremasteric pedicle and the genito-femoral nerve have been preserved they should be led from the canal as clear of the mesh as possible.

Three or four interrupted sutures are used to fix the mesh superiorly. The two tails are now overlapped lateral to the deep ring (Figure 5)

Figure 5 Overlapping the lateral tails of the mesh

and secured by two or three interrupted sutures making sure that the cord is not constricted (Figure 6).

Figure 6 The repair completed

Closure

Having checked for haemostasis and safeguarded the iliohypogastric nerve, the cord is replaced. At this stage, I leave 2 or 3ml of bupivacaine in the inguinal canal before closing the external oblique aponeurosis with continuous Vicryl. I leave some more bupivacaine in the subcutaneous layers before closing the skin with a continuous 3/0 sub-cuticular Vicryl.                     

POSTOPERATIVE CARE

The early mobilisation, which has been described to the patient preoperatively, is started as soon as possible after his/her return to the ward. Postoperative analgesia is a matter of choice. A combination of diclofenac and coproxamol is satisfactory for most patients and few require analgesia after 48 hours. Patients vary in the speed with which they return to normal activities but most will have done so within 1-3 weeks. I advise all patients to start a daily walking programme on the first postoperative day, progressively increasing the distance walked. Driving is permissible when the patient feels legally able to do so - usually judged by the ability to perform a simulated emergency stop without discomfort. This is usually after 5-7 days.

Some Postoperative Problems

Patients should be told, before giving consent, about possible postoperative complications.

• Skin anaesthesia :  This is normal after this procedure. Patients should be told that this will progressively return to normal over several months.
• Skin bruising and haematoma : This can be reduced by stopping aspirin 7 days preoperatively and by restricting low dose subcutaneous heparin to those patients who satisfy local protocol criteria. A policy of heparin for all is not necessary. Ligation rather than diathermy of the superficial epigastric and superficial external pudendal veins is recommended. Patients can be reassured that bruising of the inguinal and scrotal skin is painless and self-limiting.
• Seroma : Formation of seroma can probably be reduced by limiting the extent to which tissue planes are opened and by gentle handling of tissues.
• Pain : Pain persisting beyond 3 months is an increasingly recognised complication (up to 30% of patients in some series). The ilio-inguinal and genital branch of the genitofemoral nerves must never be incorporated into a suture. Where they lie in close proximity to the mesh it is probably best to divide them cleanly.
• Ischaemic orchitis and testicular atrophy : These complications can be reduced by keeping cord dissection to a minimum. An indirect sac should never be dissected distal to the pubic tubercle. It is best transected leaving the sac distal to this level undisturbed.
• Recurrence : Hernia recurrence can be minimised by using a large size of mesh (15 x 10cm) with minimal trimming. The mesh should extend well medial to the pubic tubercle and at least 2-3cm lateral to the deep ring.

Apart from skin anaesthesia the majority of patients have no such problems.